README
¶
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Go configuration with fangs!
Many Go projects are built using Viper including:
- Hugo
- EMC RexRay
- Imgur’s Incus
- Nanobox/Nanopack
- Docker Notary
- BloomApi
- doctl
- Clairctl
- Mercure
- Meshery
- Bearer
- Coder
- Vitess
Install
go get github.com/spf13/viper
Note: Viper uses Go Modules to manage dependencies.
What is Viper?
Viper is a complete configuration solution for Go applications including 12-Factor apps. It is designed to work within an application, and can handle all types of configuration needs and formats. It supports:
- setting defaults
- reading from JSON, TOML, YAML, HCL, envfile and Java properties config files
- live watching and re-reading of config files (optional)
- reading from environment variables
- reading from remote config systems (etcd or Consul), and watching changes
- reading from command line flags
- reading from buffer
- setting explicit values
Viper can be thought of as a registry for all of your applications configuration needs.
Why Viper?
When building a modern application, you don’t want to worry about configuration file formats; you want to focus on building awesome software. Viper is here to help with that.
Viper does the following for you:
- Find, load, and unmarshal a configuration file in JSON, TOML, YAML, HCL, INI, envfile or Java properties formats.
- Provide a mechanism to set default values for your different configuration options.
- Provide a mechanism to set override values for options specified through command line flags.
- Provide an alias system to easily rename parameters without breaking existing code.
- Make it easy to tell the difference between when a user has provided a command line or config file which is the same as the default.
Viper uses the following precedence order. Each item takes precedence over the item below it:
- explicit call to
Set
- flag
- env
- config
- key/value store
- default
Important: Viper configuration keys are case insensitive. There are ongoing discussions about making that optional.
Putting Values into Viper
Establishing Defaults
A good configuration system will support default values. A default value is not required for a key, but it’s useful in the event that a key hasn't been set via config file, environment variable, remote configuration or flag.
Examples:
viper.SetDefault("ContentDir", "content")
viper.SetDefault("LayoutDir", "layouts")
viper.SetDefault("Taxonomies", map[string]string{"tag": "tags", "category": "categories"})
Reading Config Files
Viper requires minimal configuration so it knows where to look for config files. Viper supports JSON, TOML, YAML, HCL, INI, envfile and Java Properties files. Viper can search multiple paths, but currently a single Viper instance only supports a single configuration file. Viper does not default to any configuration search paths leaving defaults decision to an application.
Here is an example of how to use Viper to search for and read a configuration file. None of the specific paths are required, but at least one path should be provided where a configuration file is expected.
viper.SetConfigName("config") // name of config file (without extension)
viper.SetConfigType("yaml") // REQUIRED if the config file does not have the extension in the name
viper.AddConfigPath("/etc/appname/") // path to look for the config file in
viper.AddConfigPath("$HOME/.appname") // call multiple times to add many search paths
viper.AddConfigPath(".") // optionally look for config in the working directory
err := viper.ReadInConfig() // Find and read the config file
if err != nil { // Handle errors reading the config file
panic(fmt.Errorf("fatal error config file: %w", err))
}
You can handle the specific case where no config file is found like this:
if err := viper.ReadInConfig(); err != nil {
if _, ok := err.(viper.ConfigFileNotFoundError); ok {
// Config file not found; ignore error if desired
} else {
// Config file was found but another error was produced
}
}
// Config file found and successfully parsed
NOTE [since 1.6]: You can also have a file without an extension and specify the format programmatically. For those configuration files that lie in the home of the user without any extension like .bashrc
Writing Config Files
Reading from config files is useful, but at times you want to store all modifications made at run time. For that, a bunch of commands are available, each with its own purpose:
- WriteConfig - writes the current viper configuration to the predefined path, if exists. Errors if no predefined path. Will overwrite the current config file, if it exists.
- SafeWriteConfig - writes the current viper configuration to the predefined path. Errors if no predefined path. Will not overwrite the current config file, if it exists.
- WriteConfigAs - writes the current viper configuration to the given filepath. Will overwrite the given file, if it exists.
- SafeWriteConfigAs - writes the current viper configuration to the given filepath. Will not overwrite the given file, if it exists.
As a rule of the thumb, everything marked with safe won't overwrite any file, but just create if not existent, whilst the default behavior is to create or truncate.
A small examples section:
viper.WriteConfig() // writes current config to predefined path set by 'viper.AddConfigPath()' and 'viper.SetConfigName'
viper.SafeWriteConfig()
viper.WriteConfigAs("/path/to/my/.config")
viper.SafeWriteConfigAs("/path/to/my/.config") // will error since it has already been written
viper.SafeWriteConfigAs("/path/to/my/.other_config")
Watching and re-reading config files
Viper supports the ability to have your application live read a config file while running.
Gone are the days of needing to restart a server to have a config take effect, viper powered applications can read an update to a config file while running and not miss a beat.
Simply tell the viper instance to watchConfig. Optionally you can provide a function for Viper to run each time a change occurs.
Make sure you add all of the configPaths prior to calling WatchConfig()
viper.OnConfigChange(func(e fsnotify.Event) {
fmt.Println("Config file changed:", e.Name)
})
viper.WatchConfig()
Reading Config from io.Reader
Viper predefines many configuration sources such as files, environment variables, flags, and remote K/V store, but you are not bound to them. You can also implement your own required configuration source and feed it to viper.
viper.SetConfigType("yaml") // or viper.SetConfigType("YAML")
// any approach to require this configuration into your program.
var yamlExample = []byte(`
Hacker: true
name: steve
hobbies:
- skateboarding
- snowboarding
- go
clothing:
jacket: leather
trousers: denim
age: 35
eyes : brown
beard: true
`)
viper.ReadConfig(bytes.NewBuffer(yamlExample))
viper.Get("name") // this would be "steve"
Setting Overrides
These could be from a command line flag, or from your own application logic.
viper.Set("Verbose", true)
viper.Set("LogFile", LogFile)
viper.Set("host.port", 5899) // set subset
Registering and Using Aliases
Aliases permit a single value to be referenced by multiple keys
viper.RegisterAlias("loud", "Verbose")
viper.Set("verbose", true) // same result as next line
viper.Set("loud", true) // same result as prior line
viper.GetBool("loud") // true
viper.GetBool("verbose") // true
Working with Environment Variables
Viper has full support for environment variables. This enables 12 factor applications out of the box. There are five methods that exist to aid working with ENV:
AutomaticEnv()
BindEnv(string...) : error
SetEnvPrefix(string)
SetEnvKeyReplacer(string...) *strings.Replacer
AllowEmptyEnv(bool)
When working with ENV variables, it’s important to recognize that Viper treats ENV variables as case sensitive.
Viper provides a mechanism to try to ensure that ENV variables are unique. By
using SetEnvPrefix
, you can tell Viper to use a prefix while reading from
the environment variables. Both BindEnv
and AutomaticEnv
will use this
prefix.
BindEnv
takes one or more parameters. The first parameter is the key name, the
rest are the name of the environment variables to bind to this key. If more than
one are provided, they will take precedence in the specified order. The name of
the environment variable is case sensitive. If the ENV variable name is not provided, then
Viper will automatically assume that the ENV variable matches the following format: prefix + "_" + the key name in ALL CAPS. When you explicitly provide the ENV variable name (the second parameter),
it does not automatically add the prefix. For example if the second parameter is "id",
Viper will look for the ENV variable "ID".
One important thing to recognize when working with ENV variables is that the
value will be read each time it is accessed. Viper does not fix the value when
the BindEnv
is called.
AutomaticEnv
is a powerful helper especially when combined with
SetEnvPrefix
. When called, Viper will check for an environment variable any
time a viper.Get
request is made. It will apply the following rules. It will
check for an environment variable with a name matching the key uppercased and
prefixed with the EnvPrefix
if set.
SetEnvKeyReplacer
allows you to use a strings.Replacer
object to rewrite Env
keys to an extent. This is useful if you want to use -
or something in your
Get()
calls, but want your environmental variables to use _
delimiters. An
example of using it can be found in viper_test.go
.
Alternatively, you can use EnvKeyReplacer
with NewWithOptions
factory function.
Unlike SetEnvKeyReplacer
, it accepts a StringReplacer
interface allowing you to write custom string replacing logic.
By default empty environment variables are considered unset and will fall back to
the next configuration source. To treat empty environment variables as set, use
the AllowEmptyEnv
method.
Env example
SetEnvPrefix("spf") // will be uppercased automatically
BindEnv("id")
os.Setenv("SPF_ID", "13") // typically done outside of the app
id := Get("id") // 13
Working with Flags
Viper has the ability to bind to flags. Specifically, Viper supports Pflags
as used in the Cobra library.
Like BindEnv
, the value is not set when the binding method is called, but when
it is accessed. This means you can bind as early as you want, even in an
init()
function.
For individual flags, the BindPFlag()
method provides this functionality.
Example:
serverCmd.Flags().Int("port", 1138, "Port to run Application server on")
viper.BindPFlag("port", serverCmd.Flags().Lookup("port"))
You can also bind an existing set of pflags (pflag.FlagSet):
Example:
pflag.Int("flagname", 1234, "help message for flagname")
pflag.Parse()
viper.BindPFlags(pflag.CommandLine)
i := viper.GetInt("flagname") // retrieve values from viper instead of pflag
The use of pflag in Viper does not preclude the use of other packages that use the flag package from the standard library. The pflag package can handle the flags defined for the flag package by importing these flags. This is accomplished by a calling a convenience function provided by the pflag package called AddGoFlagSet().
Example:
package main
import (
"flag"
"github.com/spf13/pflag"
)
func main() {
// using standard library "flag" package
flag.Int("flagname", 1234, "help message for flagname")
pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
pflag.Parse()
viper.BindPFlags(pflag.CommandLine)
i := viper.GetInt("flagname") // retrieve value from viper
// ...
}
Flag interfaces
Viper provides two Go interfaces to bind other flag systems if you don’t use Pflags
.
FlagValue
represents a single flag. This is a very simple example on how to implement this interface:
type myFlag struct {}
func (f myFlag) HasChanged() bool { return false }
func (f myFlag) Name() string { return "my-flag-name" }
func (f myFlag) ValueString() string { return "my-flag-value" }
func (f myFlag) ValueType() string { return "string" }
Once your flag implements this interface, you can simply tell Viper to bind it:
viper.BindFlagValue("my-flag-name", myFlag{})
FlagValueSet
represents a group of flags. This is a very simple example on how to implement this interface:
type myFlagSet struct {
flags []myFlag
}
func (f myFlagSet) VisitAll(fn func(FlagValue)) {
for _, flag := range flags {
fn(flag)
}
}
Once your flag set implements this interface, you can simply tell Viper to bind it:
fSet := myFlagSet{
flags: []myFlag{myFlag{}, myFlag{}},
}
viper.BindFlagValues("my-flags", fSet)
Remote Key/Value Store Support
To enable remote support in Viper, do a blank import of the viper/remote
package:
import _ "github.com/spf13/viper/remote"
Viper will read a config string (as JSON, TOML, YAML, HCL or envfile) retrieved from a path in a Key/Value store such as etcd or Consul. These values take precedence over default values, but are overridden by configuration values retrieved from disk, flags, or environment variables.
Viper supports multiple hosts. To use, pass a list of endpoints separated by ;
. For example http://127.0.0.1:4001;http://127.0.0.1:4002
.
Viper uses crypt to retrieve configuration from the K/V store, which means that you can store your configuration values encrypted and have them automatically decrypted if you have the correct gpg keyring. Encryption is optional.
You can use remote configuration in conjunction with local configuration, or independently of it.
crypt
has a command-line helper that you can use to put configurations in your
K/V store. crypt
defaults to etcd on http://127.0.0.1:4001.
$ go get github.com/sagikazarmark/crypt/bin/crypt
$ crypt set -plaintext /config/hugo.json /Users/hugo/settings/config.json
Confirm that your value was set:
$ crypt get -plaintext /config/hugo.json
See the crypt
documentation for examples of how to set encrypted values, or
how to use Consul.
Remote Key/Value Store Example - Unencrypted
etcd
viper.AddRemoteProvider("etcd", "http://127.0.0.1:4001","/config/hugo.json")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
etcd3
viper.AddRemoteProvider("etcd3", "http://127.0.0.1:4001","/config/hugo.json")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
Consul
You need to set a key to Consul key/value storage with JSON value containing your desired config.
For example, create a Consul key/value store key MY_CONSUL_KEY
with value:
{
"port": 8080,
"hostname": "myhostname.com"
}
viper.AddRemoteProvider("consul", "localhost:8500", "MY_CONSUL_KEY")
viper.SetConfigType("json") // Need to explicitly set this to json
err := viper.ReadRemoteConfig()
fmt.Println(viper.Get("port")) // 8080
fmt.Println(viper.Get("hostname")) // myhostname.com
Firestore
viper.AddRemoteProvider("firestore", "google-cloud-project-id", "collection/document")
viper.SetConfigType("json") // Config's format: "json", "toml", "yaml", "yml"
err := viper.ReadRemoteConfig()
Of course, you're allowed to use SecureRemoteProvider
also
NATS
viper.AddRemoteProvider("nats", "nats://127.0.0.1:4222", "myapp.config")
viper.SetConfigType("json")
err := viper.ReadRemoteConfig()
Remote Key/Value Store Example - Encrypted
viper.AddSecureRemoteProvider("etcd","http://127.0.0.1:4001","/config/hugo.json","/etc/secrets/mykeyring.gpg")
viper.SetConfigType("json") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
err := viper.ReadRemoteConfig()
Watching Changes in etcd - Unencrypted
// alternatively, you can create a new viper instance.
var runtime_viper = viper.New()
runtime_viper.AddRemoteProvider("etcd", "http://127.0.0.1:4001", "/config/hugo.yml")
runtime_viper.SetConfigType("yaml") // because there is no file extension in a stream of bytes, supported extensions are "json", "toml", "yaml", "yml", "properties", "props", "prop", "env", "dotenv"
// read from remote config the first time.
err := runtime_viper.ReadRemoteConfig()
// unmarshal config
runtime_viper.Unmarshal(&runtime_conf)
// open a goroutine to watch remote changes forever
go func(){
for {
time.Sleep(time.Second * 5) // delay after each request
// currently, only tested with etcd support
err := runtime_viper.WatchRemoteConfig()
if err != nil {
log.Errorf("unable to read remote config: %v", err)
continue
}
// unmarshal new config into our runtime config struct. you can also use channel
// to implement a signal to notify the system of the changes
runtime_viper.Unmarshal(&runtime_conf)
}
}()
Getting Values From Viper
In Viper, there are a few ways to get a value depending on the value’s type. The following functions and methods exist:
Get(key string) : any
GetBool(key string) : bool
GetFloat64(key string) : float64
GetInt(key string) : int
GetIntSlice(key string) : []int
GetString(key string) : string
GetStringMap(key string) : map[string]any
GetStringMapString(key string) : map[string]string
GetStringSlice(key string) : []string
GetTime(key string) : time.Time
GetDuration(key string) : time.Duration
IsSet(key string) : bool
AllSettings() : map[string]any
One important thing to recognize is that each Get function will return a zero
value if it’s not found. To check if a given key exists, the IsSet()
method
has been provided.
The zero value will also be returned if the value is set, but fails to parse as the requested type.
Example:
viper.GetString("logfile") // case-insensitive Setting & Getting
if viper.GetBool("verbose") {
fmt.Println("verbose enabled")
}
Accessing nested keys
The accessor methods also accept formatted paths to deeply nested keys. For example, if the following JSON file is loaded:
{
"host": {
"address": "localhost",
"port": 5799
},
"datastore": {
"metric": {
"host": "127.0.0.1",
"port": 3099
},
"warehouse": {
"host": "198.0.0.1",
"port": 2112
}
}
}
Viper can access a nested field by passing a .
delimited path of keys:
GetString("datastore.metric.host") // (returns "127.0.0.1")
This obeys the precedence rules established above; the search for the path will cascade through the remaining configuration registries until found.
For example, given this configuration file, both datastore.metric.host
and
datastore.metric.port
are already defined (and may be overridden). If in addition
datastore.metric.protocol
was defined in the defaults, Viper would also find it.
However, if datastore.metric
was overridden (by a flag, an environment variable,
the Set()
method, …) with an immediate value, then all sub-keys of
datastore.metric
become undefined, they are “shadowed” by the higher-priority
configuration level.
Viper can access array indices by using numbers in the path. For example:
{
"host": {
"address": "localhost",
"ports": [
5799,
6029
]
},
"datastore": {
"metric": {
"host": "127.0.0.1",
"port": 3099
},
"warehouse": {
"host": "198.0.0.1",
"port": 2112
}
}
}
GetInt("host.ports.1") // returns 6029
Lastly, if there exists a key that matches the delimited key path, its value will be returned instead. E.g.
{
"datastore.metric.host": "0.0.0.0",
"host": {
"address": "localhost",
"port": 5799
},
"datastore": {
"metric": {
"host": "127.0.0.1",
"port": 3099
},
"warehouse": {
"host": "198.0.0.1",
"port": 2112
}
}
}
GetString("datastore.metric.host") // returns "0.0.0.0"
Extracting a sub-tree
When developing reusable modules, it's often useful to extract a subset of the configuration and pass it to a module. This way the module can be instantiated more than once, with different configurations.
For example, an application might use multiple different cache stores for different purposes:
cache:
cache1:
max-items: 100
item-size: 64
cache2:
max-items: 200
item-size: 80
We could pass the cache name to a module (eg. NewCache("cache1")
),
but it would require weird concatenation for accessing config keys and would be less separated from the global config.
So instead of doing that let's pass a Viper instance to the constructor that represents a subset of the configuration:
cache1Config := viper.Sub("cache.cache1")
if cache1Config == nil { // Sub returns nil if the key cannot be found
panic("cache configuration not found")
}
cache1 := NewCache(cache1Config)
Note: Always check the return value of Sub
. It returns nil
if a key cannot be found.
Internally, the NewCache
function can address max-items
and item-size
keys directly:
func NewCache(v *Viper) *Cache {
return &Cache{
MaxItems: v.GetInt("max-items"),
ItemSize: v.GetInt("item-size"),
}
}
The resulting code is easy to test, since it's decoupled from the main config structure, and easier to reuse (for the same reason).
Unmarshaling
You also have the option of Unmarshaling all or a specific value to a struct, map, etc.
There are two methods to do this:
Unmarshal(rawVal any) : error
UnmarshalKey(key string, rawVal any) : error
Example:
type config struct {
Port int
Name string
PathMap string `mapstructure:"path_map"`
}
var C config
err := viper.Unmarshal(&C)
if err != nil {
t.Fatalf("unable to decode into struct, %v", err)
}
If you want to unmarshal configuration where the keys themselves contain dot (the default key delimiter), you have to change the delimiter:
v := viper.NewWithOptions(viper.KeyDelimiter("::"))
v.SetDefault("chart::values", map[string]any{
"ingress": map[string]any{
"annotations": map[string]any{
"traefik.frontend.rule.type": "PathPrefix",
"traefik.ingress.kubernetes.io/ssl-redirect": "true",
},
},
})
type config struct {
Chart struct{
Values map[string]any
}
}
var C config
v.Unmarshal(&C)
Viper also supports unmarshaling into embedded structs:
/*
Example config:
module:
enabled: true
token: 89h3f98hbwf987h3f98wenf89ehf
*/
type config struct {
Module struct {
Enabled bool
moduleConfig `mapstructure:",squash"`
}
}
// moduleConfig could be in a module specific package
type moduleConfig struct {
Token string
}
var C config
err := viper.Unmarshal(&C)
if err != nil {
t.Fatalf("unable to decode into struct, %v", err)
}
Viper uses github.com/go-viper/mapstructure under the hood for unmarshaling values which uses mapstructure
tags by default.
Decoding custom formats
A frequently requested feature for Viper is adding more value formats and decoders. For example, parsing character (dot, comma, semicolon, etc) separated strings into slices.
This is already available in Viper using mapstructure decode hooks.
Read more about the details in this blog post.
Marshalling to string
You may need to marshal all the settings held in viper into a string rather than write them to a file.
You can use your favorite format's marshaller with the config returned by AllSettings()
.
import (
yaml "gopkg.in/yaml.v2"
// ...
)
func yamlStringSettings() string {
c := viper.AllSettings()
bs, err := yaml.Marshal(c)
if err != nil {
log.Fatalf("unable to marshal config to YAML: %v", err)
}
return string(bs)
}
Viper or Vipers?
Viper comes with a global instance (singleton) out of the box.
Although it makes setting up configuration easy, using it is generally discouraged as it makes testing harder and can lead to unexpected behavior.
The best practice is to initialize a Viper instance and pass that around when necessary.
The global instance MAY be deprecated in the future. See #1855 for more details.
Working with multiple vipers
You can also create many different vipers for use in your application. Each will have its own unique set of configurations and values. Each can read from a different config file, key value store, etc. All of the functions that viper package supports are mirrored as methods on a viper.
Example:
x := viper.New()
y := viper.New()
x.SetDefault("ContentDir", "content")
y.SetDefault("ContentDir", "foobar")
//...
When working with multiple vipers, it is up to the user to keep track of the different vipers.
Q & A
Why is it called “Viper”?
A: Viper is designed to be a companion to Cobra. While both can operate completely independently, together they make a powerful pair to handle much of your application foundation needs.
Why is it called “Cobra”?
Is there a better name for a commander?
Does Viper support case sensitive keys?
tl;dr: No.
Viper merges configuration from various sources, many of which are either case insensitive or uses different casing than the rest of the sources (eg. env vars). In order to provide the best experience when using multiple sources, the decision has been made to make all keys case insensitive.
There has been several attempts to implement case sensitivity, but unfortunately it's not that trivial. We might take a stab at implementing it in Viper v2, but despite the initial noise, it does not seem to be requested that much.
You can vote for case sensitivity by filling out this feedback form: https://forms.gle/R6faU74qPRPAzchZ9
Is it safe to concurrently read and write to a viper?
No, you will need to synchronize access to the viper yourself (for example by using the sync
package). Concurrent reads and writes can cause a panic.
Troubleshooting
See TROUBLESHOOTING.md.
Development
For an optimal developer experience, it is recommended to install Nix and direnv.
Alternatively, install Go on your computer then run make deps
to install the rest of the dependencies.
Run the test suite:
make test
Run linters:
make lint # pass -j option to run them in parallel
Some linter violations can automatically be fixed:
make fmt
License
The project is licensed under the MIT License.
Documentation
¶
Index ¶
- Variables
- func AddConfigPath(in string)
- func AddRemoteProvider(provider, endpoint, path string) error
- func AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error
- func AllKeys() []string
- func AllSettings() map[string]any
- func AllowEmptyEnv(allowEmptyEnv bool)
- func AutomaticEnv()
- func BindEnv(input ...string) error
- func BindFlagValue(key string, flag FlagValue) error
- func BindFlagValues(flags FlagValueSet) error
- func BindPFlag(key string, flag *pflag.Flag) error
- func BindPFlags(flags *pflag.FlagSet) error
- func ConfigFileUsed() string
- func Debug()
- func DebugTo(w io.Writer)
- func Get(key string) any
- func GetBool(key string) bool
- func GetDuration(key string) time.Duration
- func GetEnvPrefix() string
- func GetFloat64(key string) float64
- func GetInt(key string) int
- func GetInt32(key string) int32
- func GetInt64(key string) int64
- func GetIntSlice(key string) []int
- func GetSizeInBytes(key string) uint
- func GetString(key string) string
- func GetStringMap(key string) map[string]any
- func GetStringMapString(key string) map[string]string
- func GetStringMapStringSlice(key string) map[string][]string
- func GetStringSlice(key string) []string
- func GetTime(key string) time.Time
- func GetUint(key string) uint
- func GetUint16(key string) uint16
- func GetUint32(key string) uint32
- func GetUint64(key string) uint64
- func InConfig(key string) bool
- func IsSet(key string) bool
- func MergeConfig(in io.Reader) error
- func MergeConfigMap(cfg map[string]any) error
- func MergeInConfig() error
- func MustBindEnv(input ...string)
- func OnConfigChange(run func(in fsnotify.Event))
- func ReadConfig(in io.Reader) error
- func ReadInConfig() error
- func ReadRemoteConfig() error
- func RegisterAlias(alias, key string)
- func Reset()
- func SafeWriteConfig() error
- func SafeWriteConfigAs(filename string) error
- func Set(key string, value any)
- func SetConfigFile(in string)
- func SetConfigName(in string)
- func SetConfigPermissions(perm os.FileMode)
- func SetConfigType(in string)
- func SetDefault(key string, value any)
- func SetEnvKeyReplacer(r *strings.Replacer)
- func SetEnvPrefix(in string)
- func SetFs(fs afero.Fs)
- func SetOptions(opts ...Option)
- func SetTypeByDefaultValue(enable bool)
- func Unmarshal(rawVal any, opts ...DecoderConfigOption) error
- func UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error
- func UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error
- func WatchConfig()
- func WatchRemoteConfig() error
- func WriteConfig() error
- func WriteConfigAs(filename string) error
- func WriteConfigTo(w io.Writer) error
- type Codec
- type CodecRegistry
- type ConfigFileAlreadyExistsError
- type ConfigFileNotFoundError
- type ConfigMarshalError
- type ConfigParseError
- type Decoder
- type DecoderConfigOption
- type DecoderRegistry
- type DefaultCodecRegistry
- type Encoder
- type EncoderRegistry
- type Finder
- type FlagValue
- type FlagValueSet
- type Option
- func EnvKeyReplacer(r StringReplacer) Option
- func ExperimentalBindStruct() Option
- func ExperimentalFinder() Option
- func KeyDelimiter(d string) Option
- func WithCodecRegistry(r CodecRegistry) Option
- func WithDecodeHook(h mapstructure.DecodeHookFunc) Option
- func WithDecoderRegistry(r DecoderRegistry) Option
- func WithEncoderRegistry(r EncoderRegistry) Option
- func WithFinder(f Finder) Option
- func WithLogger(l *slog.Logger) Option
- type RemoteConfigError
- type RemoteProvider
- type RemoteResponse
- type StringReplacer
- type UnsupportedConfigError
- type UnsupportedRemoteProviderError
- type Viper
- func (v *Viper) AddConfigPath(in string)
- func (v *Viper) AddRemoteProvider(provider, endpoint, path string) error
- func (v *Viper) AddSecureRemoteProvider(provider, endpoint, path, secretkeyring string) error
- func (v *Viper) AllKeys() []string
- func (v *Viper) AllSettings() map[string]any
- func (v *Viper) AllowEmptyEnv(allowEmptyEnv bool)
- func (v *Viper) AutomaticEnv()
- func (v *Viper) BindEnv(input ...string) error
- func (v *Viper) BindFlagValue(key string, flag FlagValue) error
- func (v *Viper) BindFlagValues(flags FlagValueSet) (err error)
- func (v *Viper) BindPFlag(key string, flag *pflag.Flag) error
- func (v *Viper) BindPFlags(flags *pflag.FlagSet) error
- func (v *Viper) ConfigFileUsed() string
- func (v *Viper) Debug()
- func (v *Viper) DebugTo(w io.Writer)
- func (v *Viper) Get(key string) any
- func (v *Viper) GetBool(key string) bool
- func (v *Viper) GetDuration(key string) time.Duration
- func (v *Viper) GetEnvPrefix() string
- func (v *Viper) GetFloat64(key string) float64
- func (v *Viper) GetInt(key string) int
- func (v *Viper) GetInt32(key string) int32
- func (v *Viper) GetInt64(key string) int64
- func (v *Viper) GetIntSlice(key string) []int
- func (v *Viper) GetSizeInBytes(key string) uint
- func (v *Viper) GetString(key string) string
- func (v *Viper) GetStringMap(key string) map[string]any
- func (v *Viper) GetStringMapString(key string) map[string]string
- func (v *Viper) GetStringMapStringSlice(key string) map[string][]string
- func (v *Viper) GetStringSlice(key string) []string
- func (v *Viper) GetTime(key string) time.Time
- func (v *Viper) GetUint(key string) uint
- func (v *Viper) GetUint16(key string) uint16
- func (v *Viper) GetUint32(key string) uint32
- func (v *Viper) GetUint64(key string) uint64
- func (v *Viper) InConfig(key string) bool
- func (v *Viper) IsSet(key string) bool
- func (v *Viper) MergeConfig(in io.Reader) error
- func (v *Viper) MergeConfigMap(cfg map[string]any) error
- func (v *Viper) MergeInConfig() error
- func (v *Viper) MustBindEnv(input ...string)
- func (v *Viper) OnConfigChange(run func(in fsnotify.Event))
- func (v *Viper) ReadConfig(in io.Reader) error
- func (v *Viper) ReadInConfig() error
- func (v *Viper) ReadRemoteConfig() error
- func (v *Viper) RegisterAlias(alias, key string)
- func (v *Viper) SafeWriteConfig() error
- func (v *Viper) SafeWriteConfigAs(filename string) error
- func (v *Viper) Set(key string, value any)
- func (v *Viper) SetConfigFile(in string)
- func (v *Viper) SetConfigName(in string)
- func (v *Viper) SetConfigPermissions(perm os.FileMode)
- func (v *Viper) SetConfigType(in string)
- func (v *Viper) SetDefault(key string, value any)
- func (v *Viper) SetEnvKeyReplacer(r *strings.Replacer)
- func (v *Viper) SetEnvPrefix(in string)
- func (v *Viper) SetFs(fs afero.Fs)
- func (v *Viper) SetTypeByDefaultValue(enable bool)
- func (v *Viper) Sub(key string) *Viper
- func (v *Viper) Unmarshal(rawVal any, opts ...DecoderConfigOption) error
- func (v *Viper) UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error
- func (v *Viper) UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error
- func (v *Viper) WatchConfig()
- func (v *Viper) WatchRemoteConfig() error
- func (v *Viper) WatchRemoteConfigOnChannel() error
- func (v *Viper) WriteConfig() error
- func (v *Viper) WriteConfigAs(filename string) error
- func (v *Viper) WriteConfigTo(w io.Writer) error
Constants ¶
This section is empty.
Variables ¶
var RemoteConfig remoteConfigFactory
RemoteConfig is optional, see the remote package.
var SupportedExts = []string{"json", "toml", "yaml", "yml", "properties", "props", "prop", "hcl", "tfvars", "dotenv", "env", "ini"}
SupportedExts are universally supported extensions.
var SupportedRemoteProviders = []string{"etcd", "etcd3", "consul", "firestore", "nats"}
SupportedRemoteProviders are universally supported remote providers.
Functions ¶
func AddConfigPath ¶
func AddConfigPath(in string)
AddConfigPath adds a path for Viper to search for the config file in. Can be called multiple times to define multiple search paths.
func AddRemoteProvider ¶
AddRemoteProvider adds a remote configuration source. Remote Providers are searched in the order they are added. provider is a string value: "etcd", "etcd3", "consul", "firestore" or "nats" are currently supported. endpoint is the url. etcd requires http://ip:port, consul requires ip:port, nats requires nats://ip:port path is the path in the k/v store to retrieve configuration To retrieve a config file called myapp.json from /configs/myapp.json you should set path to /configs and set config name (SetConfigName()) to "myapp".
func AddSecureRemoteProvider ¶
AddSecureRemoteProvider adds a remote configuration source. Secure Remote Providers are searched in the order they are added. provider is a string value: "etcd", "etcd3", "consul", "firestore" or "nats" are currently supported. endpoint is the url. etcd requires http://ip:port consul requires ip:port secretkeyring is the filepath to your openpgp secret keyring. e.g. /etc/secrets/myring.gpg path is the path in the k/v store to retrieve configuration To retrieve a config file called myapp.json from /configs/myapp.json you should set path to /configs and set config name (SetConfigName()) to "myapp". Secure Remote Providers are implemented with github.com/sagikazarmark/crypt.
func AllKeys ¶
func AllKeys() []string
AllKeys returns all keys holding a value, regardless of where they are set. Nested keys are returned with a v.keyDelim separator.
func AllSettings ¶
AllSettings merges all settings and returns them as a map[string]any.
func AllowEmptyEnv ¶
func AllowEmptyEnv(allowEmptyEnv bool)
AllowEmptyEnv tells Viper to consider set, but empty environment variables as valid values instead of falling back. For backward compatibility reasons this is false by default.
func AutomaticEnv ¶
func AutomaticEnv()
AutomaticEnv makes Viper check if environment variables match any of the existing keys (config, default or flags). If matching env vars are found, they are loaded into Viper.
func BindEnv ¶
BindEnv binds a Viper key to a ENV variable. ENV variables are case sensitive. If only a key is provided, it will use the env key matching the key, uppercased. If more arguments are provided, they will represent the env variable names that should bind to this key and will be taken in the specified order. EnvPrefix will be used when set when env name is not provided.
func BindFlagValue ¶
BindFlagValue binds a specific key to a FlagValue.
func BindFlagValues ¶
func BindFlagValues(flags FlagValueSet) error
BindFlagValues binds a full FlagValue set to the configuration, using each flag's long name as the config key.
func BindPFlag ¶
BindPFlag binds a specific key to a pflag (as used by cobra). Example (where serverCmd is a Cobra instance):
serverCmd.Flags().Int("port", 1138, "Port to run Application server on") Viper.BindPFlag("port", serverCmd.Flags().Lookup("port"))
func BindPFlags ¶
BindPFlags binds a full flag set to the configuration, using each flag's long name as the config key.
func ConfigFileUsed ¶
func ConfigFileUsed() string
ConfigFileUsed returns the file used to populate the config registry.
func Get ¶
Get can retrieve any value given the key to use. Get is case-insensitive for a key. Get has the behavior of returning the value associated with the first place from where it is set. Viper will check in the following order: override, flag, env, config file, key/value store, default
Get returns an interface. For a specific value use one of the Get____ methods.
func GetDuration ¶
GetDuration returns the value associated with the key as a duration.
func GetEnvPrefix ¶
func GetEnvPrefix() string
func GetFloat64 ¶
GetFloat64 returns the value associated with the key as a float64.
func GetIntSlice ¶
GetIntSlice returns the value associated with the key as a slice of int values.
func GetSizeInBytes ¶
GetSizeInBytes returns the size of the value associated with the given key in bytes.
func GetStringMap ¶
GetStringMap returns the value associated with the key as a map of interfaces.
func GetStringMapString ¶
GetStringMapString returns the value associated with the key as a map of strings.
func GetStringMapStringSlice ¶
GetStringMapStringSlice returns the value associated with the key as a map to a slice of strings.
func GetStringSlice ¶
GetStringSlice returns the value associated with the key as a slice of strings.
func IsSet ¶
IsSet checks to see if the key has been set in any of the data locations. IsSet is case-insensitive for a key.
func MergeConfig ¶
MergeConfig merges a new configuration with an existing config.
func MergeConfigMap ¶
MergeConfigMap merges the configuration from the map given with an existing config. Note that the map given may be modified.
func MergeInConfig ¶
func MergeInConfig() error
MergeInConfig merges a new configuration with an existing config.
func MustBindEnv ¶
func MustBindEnv(input ...string)
MustBindEnv wraps BindEnv in a panic. If there is an error binding an environment variable, MustBindEnv will panic.
func OnConfigChange ¶
OnConfigChange sets the event handler that is called when a config file changes.
func ReadConfig ¶
ReadConfig will read a configuration file, setting existing keys to nil if the key does not exist in the file.
func ReadInConfig ¶
func ReadInConfig() error
ReadInConfig will discover and load the configuration file from disk and key/value stores, searching in one of the defined paths.
func ReadRemoteConfig ¶
func ReadRemoteConfig() error
ReadRemoteConfig attempts to get configuration from a remote source and read it in the remote configuration registry.
func RegisterAlias ¶
func RegisterAlias(alias, key string)
RegisterAlias creates an alias that provides another accessor for the same key. This enables one to change a name without breaking the application.
func Reset ¶
func Reset()
Reset is intended for testing, will reset all to default settings. In the public interface for the viper package so applications can use it in their testing as well.
func SafeWriteConfig ¶
func SafeWriteConfig() error
SafeWriteConfig writes current configuration to file only if the file does not exist.
func SafeWriteConfigAs ¶
SafeWriteConfigAs writes current configuration to a given filename if it does not exist.
func Set ¶
Set sets the value for the key in the override register. Set is case-insensitive for a key. Will be used instead of values obtained via flags, config file, ENV, default, or key/value store.
func SetConfigFile ¶
func SetConfigFile(in string)
SetConfigFile explicitly defines the path, name and extension of the config file. Viper will use this and not check any of the config paths.
func SetConfigName ¶
func SetConfigName(in string)
SetConfigName sets name for the config file. Does not include extension.
func SetConfigPermissions ¶
SetConfigPermissions sets the permissions for the config file.
func SetConfigType ¶
func SetConfigType(in string)
SetConfigType sets the type of the configuration returned by the remote source, e.g. "json".
func SetDefault ¶
SetDefault sets the default value for this key. SetDefault is case-insensitive for a key. Default only used when no value is provided by the user via flag, config or ENV.
func SetEnvKeyReplacer ¶
SetEnvKeyReplacer sets the strings.Replacer on the viper object Useful for mapping an environmental variable to a key that does not match it.
func SetEnvPrefix ¶
func SetEnvPrefix(in string)
SetEnvPrefix defines a prefix that ENVIRONMENT variables will use. E.g. if your prefix is "spf", the env registry will look for env variables that start with "SPF_".
func SetOptions ¶
func SetOptions(opts ...Option)
SetOptions sets the options on the global Viper instance.
Be careful when using this function: subsequent calls may override options you set. It's always better to use a local Viper instance.
func SetTypeByDefaultValue ¶
func SetTypeByDefaultValue(enable bool)
SetTypeByDefaultValue enables or disables the inference of a key value's type when the Get function is used based upon a key's default value as opposed to the value returned based on the normal fetch logic.
For example, if a key has a default value of []string{} and the same key is set via an environment variable to "a b c", a call to the Get function would return a string slice for the key if the key's type is inferred by the default value and the Get function would return:
[]string {"a", "b", "c"}
Otherwise the Get function would return:
"a b c"
func Unmarshal ¶
func Unmarshal(rawVal any, opts ...DecoderConfigOption) error
Unmarshal unmarshals the config into a Struct. Make sure that the tags on the fields of the structure are properly set.
func UnmarshalExact ¶
func UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error
UnmarshalExact unmarshals the config into a Struct, erroring if a field is nonexistent in the destination struct.
func UnmarshalKey ¶
func UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error
UnmarshalKey takes a single key and unmarshals it into a Struct.
func WatchRemoteConfig ¶
func WatchRemoteConfig() error
func WriteConfigAs ¶
WriteConfigAs writes current configuration to a given filename.
Types ¶
type CodecRegistry ¶
type CodecRegistry interface { EncoderRegistry DecoderRegistry }
CodecRegistry combines EncoderRegistry and DecoderRegistry interfaces.
type ConfigFileAlreadyExistsError ¶
type ConfigFileAlreadyExistsError string
ConfigFileAlreadyExistsError denotes failure to write new configuration file.
func (ConfigFileAlreadyExistsError) Error ¶
func (faee ConfigFileAlreadyExistsError) Error() string
Error returns the formatted error when configuration already exists.
type ConfigFileNotFoundError ¶
type ConfigFileNotFoundError struct {
// contains filtered or unexported fields
}
ConfigFileNotFoundError denotes failing to find configuration file.
func (ConfigFileNotFoundError) Error ¶
func (fnfe ConfigFileNotFoundError) Error() string
Error returns the formatted configuration error.
type ConfigMarshalError ¶
type ConfigMarshalError struct {
// contains filtered or unexported fields
}
ConfigMarshalError happens when failing to marshal the configuration.
func (ConfigMarshalError) Error ¶
func (e ConfigMarshalError) Error() string
Error returns the formatted configuration error.
type ConfigParseError ¶
type ConfigParseError struct {
// contains filtered or unexported fields
}
ConfigParseError denotes failing to parse configuration file.
func (ConfigParseError) Error ¶
func (pe ConfigParseError) Error() string
Error returns the formatted configuration error.
func (ConfigParseError) Unwrap ¶
func (pe ConfigParseError) Unwrap() error
Unwrap returns the wrapped error.
type Decoder ¶
Decoder decodes the contents of a byte slice into Viper's internal data structures. It's primarily used for decoding contents of a file into a map[string]any.
type DecoderConfigOption ¶
type DecoderConfigOption func(*mapstructure.DecoderConfig)
A DecoderConfigOption can be passed to viper.Unmarshal to configure mapstructure.DecoderConfig options.
func DecodeHook ¶
func DecodeHook(hook mapstructure.DecodeHookFunc) DecoderConfigOption
DecodeHook returns a DecoderConfigOption which overrides the default DecoderConfig.DecodeHook value, the default is:
mapstructure.ComposeDecodeHookFunc( mapstructure.StringToTimeDurationHookFunc(), mapstructure.StringToSliceHookFunc(","), )
type DecoderRegistry ¶
DecoderRegistry returns an Decoder for a given format.
Format is case-insensitive.
DecoderRegistry returns an error if no Decoder is registered for the format.
type DefaultCodecRegistry ¶
type DefaultCodecRegistry struct {
// contains filtered or unexported fields
}
DefaultCodecRegistry is a simple implementation of CodecRegistry that allows registering custom [Codec]s.
func NewCodecRegistry ¶
func NewCodecRegistry() *DefaultCodecRegistry
NewCodecRegistry returns a new CodecRegistry, ready to accept custom [Codec]s.
func (*DefaultCodecRegistry) Decoder ¶
func (r *DefaultCodecRegistry) Decoder(format string) (Decoder, error)
Decoder implements the DecoderRegistry interface.
Format is case-insensitive.
func (*DefaultCodecRegistry) Encoder ¶
func (r *DefaultCodecRegistry) Encoder(format string) (Encoder, error)
Encoder implements the EncoderRegistry interface.
Format is case-insensitive.
func (*DefaultCodecRegistry) RegisterCodec ¶
func (r *DefaultCodecRegistry) RegisterCodec(format string, codec Codec) error
RegisterCodec registers a custom Codec.
Format is case-insensitive.
type Encoder ¶
Encoder encodes Viper's internal data structures into a byte representation. It's primarily used for encoding a map[string]any into a file format.
type EncoderRegistry ¶
EncoderRegistry returns an Encoder for a given format.
Format is case-insensitive.
EncoderRegistry returns an error if no Encoder is registered for the format.
type FlagValue ¶
type FlagValue interface { HasChanged() bool Name() string ValueString() string ValueType() string }
FlagValue is an interface that users can implement to bind different flags to viper.
type FlagValueSet ¶
type FlagValueSet interface {
VisitAll(fn func(FlagValue))
}
FlagValueSet is an interface that users can implement to bind a set of flags to viper.
type Option ¶
type Option interface {
// contains filtered or unexported methods
}
Option configures Viper using the functional options paradigm popularized by Rob Pike and Dave Cheney. If you're unfamiliar with this style, see https://commandcenter.blogspot.com/2014/01/self-referential-functions-and-design.html and https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis.
func EnvKeyReplacer ¶
func EnvKeyReplacer(r StringReplacer) Option
EnvKeyReplacer sets a replacer used for mapping environment variables to internal keys.
func ExperimentalBindStruct ¶
func ExperimentalBindStruct() Option
ExperimentalBindStruct tells Viper to use the new bind struct feature.
func ExperimentalFinder ¶
func ExperimentalFinder() Option
ExperimentalFinder tells Viper to use the new Finder interface for finding configuration files.
func KeyDelimiter ¶
KeyDelimiter sets the delimiter used for determining key parts. By default it's value is ".".
func WithCodecRegistry ¶
func WithCodecRegistry(r CodecRegistry) Option
WithCodecRegistry sets a custom EncoderRegistry and DecoderRegistry.
func WithDecodeHook ¶
func WithDecodeHook(h mapstructure.DecodeHookFunc) Option
WithDecodeHook sets a default decode hook for mapstructure.
func WithDecoderRegistry ¶
func WithDecoderRegistry(r DecoderRegistry) Option
WithDecoderRegistry sets a custom DecoderRegistry.
func WithEncoderRegistry ¶
func WithEncoderRegistry(r EncoderRegistry) Option
WithEncoderRegistry sets a custom EncoderRegistry.
type RemoteConfigError ¶
type RemoteConfigError string
RemoteConfigError denotes encountering an error while trying to pull the configuration from the remote provider.
func (RemoteConfigError) Error ¶
func (rce RemoteConfigError) Error() string
Error returns the formatted remote provider error.
type RemoteProvider ¶
type RemoteProvider interface { Provider() string Endpoint() string Path() string SecretKeyring() string }
RemoteProvider stores the configuration necessary to connect to a remote key/value store. Optional secretKeyring to unencrypt encrypted values can be provided.
type RemoteResponse ¶
type StringReplacer ¶
type StringReplacer interface { // Replace returns a copy of s with all replacements performed. Replace(s string) string }
StringReplacer applies a set of replacements to a string.
type UnsupportedConfigError ¶
type UnsupportedConfigError string
UnsupportedConfigError denotes encountering an unsupported configuration filetype.
func (UnsupportedConfigError) Error ¶
func (str UnsupportedConfigError) Error() string
Error returns the formatted configuration error.
type UnsupportedRemoteProviderError ¶
type UnsupportedRemoteProviderError string
UnsupportedRemoteProviderError denotes encountering an unsupported remote provider. Currently only etcd and Consul are supported.
func (UnsupportedRemoteProviderError) Error ¶
func (str UnsupportedRemoteProviderError) Error() string
Error returns the formatted remote provider error.
type Viper ¶
type Viper struct {
// contains filtered or unexported fields
}
Viper is a prioritized configuration registry. It maintains a set of configuration sources, fetches values to populate those, and provides them according to the source's priority. The priority of the sources is the following: 1. overrides 2. flags 3. env. variables 4. config file 5. key/value store 6. defaults
For example, if values from the following sources were loaded:
Defaults : { "secret": "", "user": "default", "endpoint": "https://localhost" } Config : { "user": "root" "secret": "defaultsecret" } Env : { "secret": "somesecretkey" }
The resulting config will have the following values:
{ "secret": "somesecretkey", "user": "root", "endpoint": "https://localhost" }
Note: Vipers are not safe for concurrent Get() and Set() operations.
func NewWithOptions ¶
NewWithOptions creates a new Viper instance.
func Sub ¶
Sub returns new Viper instance representing a sub tree of this instance. Sub is case-insensitive for a key.
func (*Viper) AddConfigPath ¶
func (*Viper) AddRemoteProvider ¶
func (*Viper) AddSecureRemoteProvider ¶
func (*Viper) AllSettings ¶
func (*Viper) AllowEmptyEnv ¶
func (*Viper) AutomaticEnv ¶
func (v *Viper) AutomaticEnv()
func (*Viper) BindFlagValues ¶
func (v *Viper) BindFlagValues(flags FlagValueSet) (err error)
func (*Viper) ConfigFileUsed ¶
func (*Viper) GetEnvPrefix ¶
func (*Viper) GetFloat64 ¶
func (*Viper) GetIntSlice ¶
func (*Viper) GetSizeInBytes ¶
func (*Viper) GetStringMapStringSlice ¶
func (*Viper) GetStringSlice ¶
func (*Viper) MergeInConfig ¶
func (*Viper) MustBindEnv ¶
func (*Viper) OnConfigChange ¶
OnConfigChange sets the event handler that is called when a config file changes.
func (*Viper) ReadInConfig ¶
func (*Viper) ReadRemoteConfig ¶
func (*Viper) RegisterAlias ¶
func (*Viper) SafeWriteConfig ¶
func (*Viper) SafeWriteConfigAs ¶
func (*Viper) SetConfigFile ¶
func (*Viper) SetConfigName ¶
func (*Viper) SetConfigPermissions ¶
func (*Viper) SetConfigType ¶
func (*Viper) SetDefault ¶
func (*Viper) SetEnvKeyReplacer ¶
func (*Viper) SetEnvPrefix ¶
func (*Viper) SetTypeByDefaultValue ¶
func (*Viper) UnmarshalExact ¶
func (v *Viper) UnmarshalExact(rawVal any, opts ...DecoderConfigOption) error
func (*Viper) UnmarshalKey ¶
func (v *Viper) UnmarshalKey(key string, rawVal any, opts ...DecoderConfigOption) error
func (*Viper) WatchConfig ¶
func (v *Viper) WatchConfig()
WatchConfig starts watching a config file for changes.