config

README

Config - Dynamic config interface

Provides a high level pluggable abstraction for dynamic configuration.

Interface

There's a need for dynamic configuration with namespacing, deltas for rollback, watches for changes and an audit log. At a low level we may care about server addresses changing, routing information, etc. At a high level there may be a need to control business level logic; External API Urls, Pricing information, etc.

config.New(namespace) // namespaced by service name
config.Load(namespace) // load existing namespace
config.Watch(path) // /[service]/api/urls

## Supported Backends

• Cassandra
• Zookeeper/Etcd
• Consul

Documentation

Index

• Variables
• func NewContext(ctx context.Context, c Config) context.Context
• type ChangeSet
• type Config
  • func FromContext(ctx context.Context) (Config, bool)
  • func NewConfig(opts ...Option) Config
• type Option
  • func PollInterval(i time.Duration) Option
  • func WithClient(c client.Client) Option
  • func WithReader(r Reader) Option
  • func WithSource(s Source) Option
• type Options
• type Reader
  • func NewReader() Reader
• type Source
  • func NewSource(opts ...SourceOption) Source
• type SourceOption
  • func SourceClient(c client.Client) SourceOption
  • func SourceName(n string) SourceOption
• type SourceOptions
• type SourceWatcher
• type Value
• type Values

Variables

var (
	DefaultPollInterval = time.Second * 30
	DefaultSourceName   = "MICRO:CONFIG"
)

Functions

func NewContext

func NewContext(ctx context.Context, c Config) context.Context

Types

type ChangeSet

type ChangeSet struct {
	// The time at which the last change occured
	Timestamp time.Time
	// The raw data set for the change
	Data []byte
	// Hash of the source data
	Checksum string
	// The source of this change; file, consul, etcd
	Source string
}

ChangeSet represents a set an actual source

type Config

type Config interface {
	// Config values
	Values
	// Config options
	Options() Options
	// Start/Stop for internal interval updater, etc.
	Start() error
	Stop() error
	// String name of config; platform
	String() string
}

Config is the top level config which aggregates a number of sources and provides a single merged interface.

func FromContext

func FromContext(ctx context.Context) (Config, bool)

func NewConfig

func NewConfig(opts ...Option) Config

type Option

type Option func(o *Options)

func PollInterval

func PollInterval(i time.Duration) Option

PollInterval is the time interval at which the sources are polled to retrieve config.

func WithClient

func WithClient(c client.Client) Option

func WithReader

func WithReader(r Reader) Option

WithReader is the reader used by config to parse ChangeSets, merge them and provide values. We're not as elegant here in terms of encoding.

func WithSource

func WithSource(s Source) Option

WithSource appends a source to our list of sources. This forms a hierarchy whereby all the configs are merged down with the last specified as favoured.

type Options

type Options struct {
	PollInterval time.Duration
	Reader       Reader
	Sources      []Source
	Client       client.Client
}

type Reader

type Reader interface {
	// Parse ChangeSets
	Parse(...*ChangeSet) (*ChangeSet, error)
	// As values
	Values(*ChangeSet) (Values, error)
	// Name of parser; json
	String() string
}

Reader takes a ChangeSet from a source and returns a single merged ChangeSet e.g reads ChangeSet as JSON and can merge down

func NewReader

func NewReader() Reader

New json reader

type Source

type Source interface {
	// Loads ChangeSet from the source
	Read() (*ChangeSet, error)
	// Watch for source changes
	// Returns the entire changeset
	Watch() (SourceWatcher, error)
	// Name of source
	String() string
}

Source is the source from which config is loaded. This may be a file, a url, consul, etc.

func NewSource

func NewSource(opts ...SourceOption) Source

type SourceOption

type SourceOption func(o *SourceOptions)

func SourceClient

func SourceClient(c client.Client) SourceOption

func SourceName

func SourceName(n string) SourceOption

SourceName is an option to provide name of a file, a url, key within etcd, consul, zookeeper, etc.

type SourceOptions

type SourceOptions struct {
	// Name, Url, etc
	Name string

	// Client for platform
	Client client.Client
}

type SourceWatcher

type SourceWatcher interface {
	Next() (*ChangeSet, error)
	Stop() error
}

SourceWatcher allows you to watch a source for changes Next is a blocking call which returns the next ChangeSet update. Stop Renders the watcher unusable.

type Value

type Value interface {
	Bool(def bool) bool
	Int(def int) int
	String(def string) string
	Float64(def float64) float64
	Duration(def time.Duration) time.Duration
	StringSlice(def []string) []string
	StringMap(def map[string]string) map[string]string
	Scan(val interface{}) error
	Bytes() []byte
}

Represent a value retrieved from the values loaded

type Values

type Values interface {
	// The path could be a nested structure so
	// make it a composable.
	// Returns internal cached value
	Get(path ...string) Value
	// Sets internal cached value
	Set(val interface{}, path ...string)
	// Deletes internal cached value
	Del(path ...string)
	// Returns vals as bytes
	Bytes() []byte
}

Values loaded within the config