etcdv3

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 Go to latest Published: Oct 17, 2017 License: Apache-2.0 Imports: 19 Imported by: 0

README

Etcd plugin

The Etcd plugin provides access to an etcd key-value data store.

API

Implements API described in the skeleton: The plugin is documented in more detail in the doc.go file.

Configuration

  • Location of the Etcd configuration file can be defined either by the command line flag etcdv3-config or set via the ETCDV3_CONFIG environment variable.

Status Check

  • If injected, Etcd plugin will use StatusCheck plugin to periodically issue a minimalistic GET request to check for the status of the connection. The etcd connection state affects the global status of the agent. If agent cannot establish connection with etcd, both the readiness and the liveness probe from the probe plugin will return a negative result (accessible only via REST API in such case).

Documentation

Overview

Package etcdv3 implements the key-value Data Broker client API for the etcdv3 key-value data store. See cn-infra/db/keyval for the definition of the key-value Data Broker client API.

The entity that provides access to the data store is called BytesConnectionEtcd. 

+-----------------------+       crud/watch         ______
|  BytesConnectionEtcd  |          ---->          | ETCD |
+-----------------------+        []byte           +------+

To create a BytesConnectionEtcd use the following function 

import  "github.com/ligato/cn-infra/db/keyval/etcd"

db := etcd.NewEtcdConnectionWithBytes(config)

config is a path to a file with the following format: 

key-file: <filepath>
ca-file: <filepath>
cert-file: <filepath>
insecure-skip-tls-verify: <bool>
insecure-transport: <bool>
dial-timeout: <nanoseconds>
operation-timeout: <nanoseconds>
endpoints:
  - <address_1>:<port>
  - <address_2>:<port>
  - ..
  - <address_n>:<port>

Connection to etcd is established using the provided config behind the scenes.

Alternatively, you may connect to etcd by yourself and initialize the connection object with a given client. 

db := etcd.NewEtcdConnectionUsingClient(client)

Created BytesConnectionEtcd implements Broker and KeyValProtoWatcher interfaces. The example of use can be seen below.

To insert single key-value pair into etcd run: 

db.Put(key, data)

To remove a value identified by key: 

datasync.Delete(key)

In addition to single key-value pair approach, the transaction API is provided. Transaction executes multiple operations in a more efficient way than one by one execution. 

// create new transaction
txn := db.NewTxn()

// add put operation into the transaction
txn.Put(key, value)

// add delete operation into the transaction
txn.Delete(key, value)

// try to commit the transaction
err := txn.Commit()

To retrieve a value identified by key: 

data, found, rev, err := db.GetValue(key)
if err == nil && found {
   ...
}

To retrieve all values matching a key prefix: 

itr, err := db.ListValues(key)
if err != nil {
   for {
      data, allReceived, rev, err := itr.GetNext()
      if allReceived {
          break
      }
      if err != nil {
          return err
      }
      process data...
   }
}

To retrieve values in specified key range: 

itr, err := db.ListValues(key)
if err != nil {
   for {
      data, rev, allReceived := itr.GetNext()
      if allReceived {
          break
      }
      process data...
   }
}

To list keys without fetching the values 

itr, err := db.ListKeys(prefix)
if err != nil {
   for {
      key, rev, allReceived := itr.GetNext()
      if allReceived {
          break
      }
      process key...
   }
}

To start watching changes in etcd: 

respChan := make(chan keyval.BytesWatchResp, 0)
err = dbw.Watch(respChan, key)
if err != nil {
    os.Exit(1)
}
for {
     select {
         case resp := <-respChan:
            switch resp.GetChangeType() {
            case data.Put:
            key := resp.GetKey()
                value := resp.GetValue()
                rev := resp.GetRevision()
            case data.Delete:
                ...
            }
     }
}

BytesConnectionEtcd also allows to create proxy instances (BytesBrokerWatcherEtcd) using NewBroker and NewWatcher methods. Both of them accept the prefix argument. The prefix will be automatically prepended to all keys in put/delete requests made from the proxy instances. I n case of get-like calls (GetValue, ListValues, ...) the prefix is trimmed from the key of the returned values. They contain only the part following the prefix in the key field. The created proxy instances share the connection of the BytesConnectionEtcd. 

     +-----------------------+
     | BytesBrokerWatcherEtcd |
     +-----------------------+
             |
             |
              ----------------->   +-----------------------+       crud/watch         ______
			                          |  BytesConnectionEtcd  |       ---->             | ETCD |
              ----------------->   +-----------------------+        ([]byte)         +------+
             |
             |
     +------------------------+
     | BytesBrokerWatcherEtcd |
     +------------------------+

To create proxy instances, type: 

prefixedBroker := db.NewBroker(prefix)
prefixedWatcher := db.NewWatcher(prefix)

The usage is the same as shown above.

The package also provides a proto decorator that simplifies the manipulation of proto modelled data. The proto decorator accepts arguments of type proto.message and marshals them into []byte slices. 

+-------------------+--------------------+       crud/watch         ______
|  ProtoWrapperEtcd |  ProtoWrapperEtcd  |       ---->             | ETCD |
+-------------------+--------------------+        ([]byte)         +------+
  (proto.Message)

The ProtoWrapperEtcd API is very similar to the BytesConnectionEtcd API. The difference is that arguments of type []byte are replaced by arguments of type proto.Message, and in some case one of the return values is transformed into an output argument.

Example of the decorator initialization: 

// conn is BytesConnectionEtcd initialized as shown at the top of the page
protoBroker := etcd.NewProtoWrapperEtcd(conn)

The only difference in Put/Delete functions is the type of the argument, apart from that the usage is the same as described above.

Example of retrieving single key-value pair using proto decorator: 

// if the value exists it is unmarshalled into the msg
found, rev, err := protoBroker.GetValue(key, msg)

To retrieve all values matching the key prefix use 

 resp, err := protoDb.ListValues(path)
 if err != nil {
    os.Exit(1)
 }

 for {
    // phonebook.Contact is a proto modelled structure (implementing proto.Message interface)
    contact := &phonebook.Contact{}
    // the value is unmarshaled into the contact variable
    kv, allReceived  := resp.GetNext()
    if allReceived {
       break
    }
    err = kv.GetValue(contact)
    if err != nil {
        os.Exit(1)
    }
    ... use contact
}

The Etcd plugin 

plugin := etcdv3.Plugin{}
// initialization by agent core

Plugin allows to create a broker 

broker := plugin.NewBroker(prefix)

and watcher 

watcher := plugin.NewWatcher(prefix)

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type BytesBrokerWatcherEtcd 

type BytesBrokerWatcherEtcd struct {
	logging.Logger
	// contains filtered or unexported fields
}

BytesBrokerWatcherEtcd uses BytesConnectionEtcd to access the datastore. The connection can be shared among multiple BytesBrokerWatcherEtcd. In case of accessing a particular subtree in etcd only, BytesBrokerWatcherEtcd allows to define a keyPrefix that is prepended to all keys in its methods in order to shorten keys used in arguments.

func (*BytesBrokerWatcherEtcd) Delete 

func (pdb *BytesBrokerWatcherEtcd) Delete(key string, opts ...datasync.DelOption) (existed bool, err error)

Delete calls 'Delete' function of the underlying BytesConnectionEtcd. KeyPrefix defined in constructor is prepended to the key argument.

func (*BytesBrokerWatcherEtcd) GetValue 

func (pdb *BytesBrokerWatcherEtcd) GetValue(key string) (data []byte, found bool, revision int64, err error)

GetValue calls 'GetValue' function of the underlying BytesConnectionEtcd. KeyPrefix defined in constructor is prepended to key argument.

func (*BytesBrokerWatcherEtcd) ListKeys 

func (pdb *BytesBrokerWatcherEtcd) ListKeys(prefix string) (keyval.BytesKeyIterator, error)

ListKeys calls 'ListKeys' function of the underlying BytesConnectionEtcd. KeyPrefix defined in constructor is prepended to the argument.

func (*BytesBrokerWatcherEtcd) ListValues 

func (pdb *BytesBrokerWatcherEtcd) ListValues(key string) (keyval.BytesKeyValIterator, error)

ListValues calls 'ListValues' function of the underlying BytesConnectionEtcd. KeyPrefix defined in constructor is prepended to key argument. The prefix is removed from the keys of the returned values.

func (*BytesBrokerWatcherEtcd) ListValuesRange 

func (pdb *BytesBrokerWatcherEtcd) ListValuesRange(fromPrefix string, toPrefix string) (keyval.BytesKeyValIterator, error)

ListValuesRange calls 'ListValuesRange' function of the underlying BytesConnectionEtcd. KeyPrefix defined in constructor is prepended to the arguments. The prefix is removed from the keys of the returned values.

func (*BytesBrokerWatcherEtcd) NewTxn 

func (pdb *BytesBrokerWatcherEtcd) NewTxn() keyval.BytesTxn

NewTxn creates a new transaction. KeyPrefix defined in constructor will be prepended to all key arguments in the transaction.

func (*BytesBrokerWatcherEtcd) Put 

func (pdb *BytesBrokerWatcherEtcd) Put(key string, data []byte, opts ...datasync.PutOption) error

Put calls 'Put' function of the underlying BytesConnectionEtcd. KeyPrefix defined in constructor is prepended to key argument.

func (*BytesBrokerWatcherEtcd) Watch 

func (pdb *BytesBrokerWatcherEtcd) Watch(resp func(keyval.BytesWatchResp), keys ...string) error

Watch starts subscription for changes associated with the selected <keys>. KeyPrefix defined in constructor is prepended to all <keys> in the argument list. The prefix is removed from the keys returned in watch events. Watch events will be delivered to <resp> callback.

type BytesConnectionEtcd 

type BytesConnectionEtcd struct {
	logging.Logger
	// contains filtered or unexported fields
}

BytesConnectionEtcd encapsulates the connection to etcd. It provides API to read/edit and watch values from etcd.

func NewEtcdConnectionUsingClient 

func NewEtcdConnectionUsingClient(etcdClient *clientv3.Client, log logging.Logger) (*BytesConnectionEtcd, error)

NewEtcdConnectionUsingClient creates a new instance of BytesConnectionEtcd using the provided etcdv3 client. This constructor is used primarily for testing.

func NewEtcdConnectionWithBytes 

func NewEtcdConnectionWithBytes(config ClientConfig, log logging.Logger) (*BytesConnectionEtcd, error)

NewEtcdConnectionWithBytes creates new connection to etcd based on the given config file.

func (*BytesConnectionEtcd) Close 

func (db *BytesConnectionEtcd) Close() error

Close closes the connection to ETCD.

func (*BytesConnectionEtcd) Delete 

func (db *BytesConnectionEtcd) Delete(key string, opts ...datasync.DelOption) (existed bool, err error)

Delete removes data identified by the <key>.

func (*BytesConnectionEtcd) GetValue 

func (db *BytesConnectionEtcd) GetValue(key string) (data []byte, found bool, revision int64, err error)

GetValue retrieves one key-value item from the data store. The item is identified by the provided <key>.

func (*BytesConnectionEtcd) ListKeys 

func (db *BytesConnectionEtcd) ListKeys(prefix string) (keyval.BytesKeyIterator, error)

ListKeys returns an iterator that allows to traverse all keys from data store that share the given <prefix>

func (*BytesConnectionEtcd) ListValues 

func (db *BytesConnectionEtcd) ListValues(key string) (keyval.BytesKeyValIterator, error)

ListValues returns an iterator that enables to traverse values stored under the provided <key>.

func (*BytesConnectionEtcd) ListValuesRange 

func (db *BytesConnectionEtcd) ListValuesRange(fromPrefix string, toPrefix string) (keyval.BytesKeyValIterator, error)

ListValuesRange returns an iterator that enables to traverse values stored under the keys from a given range.

func (*BytesConnectionEtcd) NewBroker 

func (db *BytesConnectionEtcd) NewBroker(prefix string) keyval.BytesBroker

NewBroker creates a new instance of a proxy that provides access to etcd. The proxy will reuse the connection from BytesConnectionEtcd. <prefix> will be prepended to the key argument in all calls from the created BytesBrokerWatcherEtcd. To avoid using a prefix pass keyval.Root constant as the argument.

func (*BytesConnectionEtcd) NewTxn 

func (db *BytesConnectionEtcd) NewTxn() keyval.BytesTxn

NewTxn creates a new transaction. A transaction can hold multiple operations that are all committed to the data store together. After a transaction has been created, one or more operations (put or delete) can be added to the transaction before it is committed.

func (*BytesConnectionEtcd) NewWatcher 

func (db *BytesConnectionEtcd) NewWatcher(prefix string) keyval.BytesWatcher

NewWatcher creates a new instance of a proxy that provides access to etcd. The proxy will reuse the connection from BytesConnectionEtcd. <prefix> will be prepended to the key argument in all calls on created BytesBrokerWatcherEtcd. To avoid using a prefix pass keyval.Root constant as argument.

func (*BytesConnectionEtcd) Put 

func (db *BytesConnectionEtcd) Put(key string, binData []byte, opts ...datasync.PutOption) error

Put writes the provided key-value item into the data store. Returns an error if the item could not be written, nil otherwise.

func (*BytesConnectionEtcd) Watch 

func (db *BytesConnectionEtcd) Watch(resp func(keyval.BytesWatchResp), keys ...string) error

Watch starts subscription for changes associated with the selected keys. Watch events will be delivered to <resp> callback.

type BytesWatchDelResp 

type BytesWatchDelResp struct {
	// contains filtered or unexported fields
}

BytesWatchDelResp is sent when a key-value pair has been removed.

func NewBytesWatchDelResp 

func NewBytesWatchDelResp(key string, revision int64) *BytesWatchDelResp

NewBytesWatchDelResp creates an instance of BytesWatchDelResp.

func (*BytesWatchDelResp) GetChangeType 

func (resp *BytesWatchDelResp) GetChangeType() datasync.PutDel

GetChangeType returns "Delete" for BytesWatchPutResp.

func (*BytesWatchDelResp) GetKey 

func (resp *BytesWatchDelResp) GetKey() string

GetKey returns the key that a value has been deleted from.

func (*BytesWatchDelResp) GetRevision 

func (resp *BytesWatchDelResp) GetRevision() int64

GetRevision returns the revision associated with the 'delete' operation.

func (*BytesWatchDelResp) GetValue 

func (resp *BytesWatchDelResp) GetValue() []byte

GetValue returns nil for BytesWatchDelResp.

type BytesWatchPutResp 

type BytesWatchPutResp struct {
	// contains filtered or unexported fields
}

BytesWatchPutResp is sent when new key-value pair has been inserted or the value has been updated.

func NewBytesWatchPutResp 

func NewBytesWatchPutResp(key string, value []byte, revision int64) *BytesWatchPutResp

NewBytesWatchPutResp creates an instance of BytesWatchPutResp.

func (*BytesWatchPutResp) GetChangeType 

func (resp *BytesWatchPutResp) GetChangeType() datasync.PutDel

GetChangeType returns "Put" for BytesWatchPutResp.

func (*BytesWatchPutResp) GetKey 

func (resp *BytesWatchPutResp) GetKey() string

GetKey returns the key that tha value has been inserted under.

func (*BytesWatchPutResp) GetRevision 

func (resp *BytesWatchPutResp) GetRevision() int64

GetRevision returns the revision associated with the 'put' operation.

func (*BytesWatchPutResp) GetValue 

func (resp *BytesWatchPutResp) GetValue() []byte

GetValue returns the value that has been inserted.

type ClientConfig 

type ClientConfig struct {
	*clientv3.Config

	// OpTimeout is the maximum amount of time the client will wait on a pending
	// operation before timing out.
	OpTimeout time.Duration
}

ClientConfig extends clientv3.Config with configuration options introduced by this package.

func ConfigToClientv3 

func ConfigToClientv3(yc *Config) (*ClientConfig, error)

ConfigToClientv3 transforms yaml configuration <yc> modelled by Config into ClientConfig, which is ready for use with the underlying coreos/etcd package. If the etcd endpoint addresses are not specified in the configuration, the function will query the ETCDV3_ENDPOINTS environment variable for a non-empty value. In neither the config nor the environment specify the endpoint location, a default address "127.0.0.1:2379" is assumed. The function may return error only if TLS connection is selected and the CA or client certificate is not accessible/valid.

type Config 

type Config struct {
	Endpoints             []string      `json:"endpoints"`
	DialTimeout           time.Duration `json:"dial-timeout"`
	OpTimeout             time.Duration `json:"operation-timeout"`
	InsecureTransport     bool          `json:"insecure-transport"`
	InsecureSkipTLSVerify bool          `json:"insecure-skip-tls-verify"`
	Certfile              string        `json:"cert-file"`
	Keyfile               string        `json:"key-file"`
	CAfile                string        `json:"ca-file"`
}

Config represents a part of the etcd configuration that can be loaded from a file. Usually, the Config is next transformed into ClientConfig using ConfigToClientv3() function for use with the coreos/etcd package.

type Deps 

type Deps struct {
	local.PluginInfraDeps // inject
}

Deps lists dependencies of the etcdv3 plugin. If injected, etcd plugin will use StatusCheck to signal the connection status.

type Plugin 

type Plugin struct {
	Deps // inject
	*plugin.Skeleton
	// contains filtered or unexported fields
}

Plugin implements etcdv3 plugin.

func FromExistingConnection 

func FromExistingConnection(connection keyval.CoreBrokerWatcher, sl servicelabel.ReaderAPI) *Plugin

FromExistingConnection is used mainly for testing to inject existing connection into the plugin. Note, need to set Deps for returned value!

func (*Plugin) AfterInit 

func (p *Plugin) AfterInit() error

AfterInit registers status polling function with StatusCheck plugin (if injected).

func (*Plugin) Close 

func (p *Plugin) Close() error

Close shutdowns the connection.

func (*Plugin) Disabled 

func (p *Plugin) Disabled() (disabled bool)

Disabled returns *true* if the plugin is not in use due to missing etcd configuration.

func (*Plugin) Init 

func (p *Plugin) Init() (err error)

Init retrieves etcd configuration and establishes a new connection with the etcd data store. If the configuration file doesn't exist or cannot be read, the returned error will be of type os.PathError. An untyped error is returned in case the file doesn't contain a valid YAML configuration. The function may also return error if TLS connection is selected and the CA or client certificate is not accessible(os.PathError)/valid(untyped). Check clientv3.New from coreos/etcd for possible errors returned when the connection cannot be established.

func (*Plugin) String 

func (p *Plugin) String() string

String returns the plugin name from dependencies if injected, "kvdbsync" otherwise.

Source Files

View all Source files

Directories

Path Synopsis
Package mocks implements an embedded etcdv3 mock used in unit & integration tests.
 Package mocks implements an embedded etcdv3 mock used in unit & integration tests.

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