etcdvar

Documentation

Overview

Package etcdvar provides a runtimevar implementation with variables backed by etcd. Use New to construct a *runtimevar.Variable.

As

etcdvar exposes the following types for As:

• Snapshot: *clientv3.GetResponse
• Error: rpctypes.EtcdError

Example

package main

import (
	"context"
	"log"

	"go.etcd.io/etcd/clientv3"
	"gocloud.dev/runtimevar"
	"gocloud.dev/runtimevar/etcdvar"
)

// MyConfig is a sample configuration struct.
type MyConfig struct {
	Server string
	Port   int
}

func main() {
	// Connect to the etcd server.
	client, err := clientv3.NewFromURL("http://your.etcd.server:9999")
	if err != nil {
		log.Fatal(err)
	}

	// Create a decoder for decoding JSON strings into MyConfig.
	decoder := runtimevar.NewDecoder(MyConfig{}, runtimevar.JSONDecode)

	// Construct a *runtimevar.Variable that watches the variable.
	// The etcd variable being referenced should have a JSON string that
	// decodes into MyConfig.
	v, err := etcdvar.New(client, "cfg-variable-name", decoder, nil)
	if err != nil {
		log.Fatal(err)
	}
	defer v.Close()

	// We can now read the current value of the variable from v.
	snapshot, err := v.Watch(context.Background())
	if err != nil {
		log.Fatal(err)
	}
	cfg := snapshot.Value.(MyConfig)
	_ = cfg
}

Index

• func New(cli *clientv3.Client, name string, decoder *runtimevar.Decoder, opts *Options) (*runtimevar.Variable, error)
• type Options

Examples

• Package

Functions

func New

func New(cli *clientv3.Client, name string, decoder *runtimevar.Decoder, opts *Options) (*runtimevar.Variable, error)

New constructs a *runtimevar.Variable that uses client to watch the variable name on an etcd server. etcd returns raw bytes; provide a decoder to decode the raw bytes into the appropriate type for runtimevar.Snapshot.Value. See the runtimevar package documentation for examples of decoders.

Types

type Options

type Options struct {
	// Timeout controls the timeout on RPCs to etcd; timeouts will result in
	// errors being returned from Watch. Defaults to 30 seconds.
	Timeout time.Duration
}

Options sets options.