clientv3

package
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 Go to latest Published: Apr 22, 2024 License: Apache-2.0 Imports: 25 Imported by: 0

README

etcd/clientv3

Godoc

etcd/clientv3 is the official Go etcd client for v3.

Install

go get github.com/coreos/etcd/clientv3

Get started

Create client using clientv3.New:

cli, err := clientv3.New(clientv3.Config{
	Endpoints:   []string{"localhost:2379", "localhost:22379", "localhost:32379"},
	DialTimeout: 5 * time.Second,
})
if err != nil {
	// handle error!
}
defer cli.Close()

etcd v3 uses gRPC for remote procedure calls. And clientv3 uses grpc-go to connect to etcd. Make sure to close the client after using it. If the client is not closed, the connection will have leaky goroutines. To specify client request timeout, pass context.WithTimeout to APIs:

ctx, cancel := context.WithTimeout(context.Background(), timeout)
resp, err := kvc.Put(ctx, "sample_key", "sample_value")
cancel()
if err != nil {
    // handle error!
}
// use the response

etcd uses cmd/vendor directory to store external dependencies, which are to be compiled into etcd release binaries. client can be imported without vendoring. For full compatibility, it is recommended to vendor builds using etcd's vendored packages, using tools like godep, as in vendor directories. For more detail, please read Go vendor design.

Error Handling

etcd client returns 2 types of errors:

  1. context error: canceled or deadline exceeded.
  2. gRPC error: see api/v3rpc/rpctypes.

Here is the example code to handle client errors:

resp, err := kvc.Put(ctx, "", "")
if err != nil {
	switch err {
	case context.Canceled:
		log.Fatalf("ctx is canceled by another routine: %v", err)
	case context.DeadlineExceeded:
		log.Fatalf("ctx is attached with a deadline is exceeded: %v", err)
	case rpctypes.ErrEmptyKey:
		log.Fatalf("client-side error: %v", err)
	default:
		log.Fatalf("bad cluster endpoints, which are not etcd servers: %v", err)
	}
}

Metrics

The etcd client optionally exposes RPC metrics through go-grpc-prometheus. See the examples.

Examples

More code examples can be found at GoDoc.

Documentation

Overview

Package clientv3 implements the official Go etcd client for v3.

Create client using `clientv3.New`: 

cli, err := clientv3.New(clientv3.Config{
	Endpoints:   []string{"localhost:2379", "localhost:22379", "localhost:32379"},
	DialTimeout: 5 * time.Second,
})
if err != nil {
	// handle error!
}
defer cli.Close()

Make sure to close the client after using it. If the client is not closed, the connection will have leaky goroutines.

To specify client request timeout, pass context.WithTimeout to APIs: 

ctx, cancel := context.WithTimeout(context.Background(), timeout)
resp, err := kvc.Put(ctx, "sample_key", "sample_value")
cancel()
if err != nil {
    // handle error!
}
// use the response

The Client has internal state (watchers and leases), so Clients should be reused instead of created as needed. Clients are safe for concurrent use by multiple goroutines.

etcd client returns 2 types of errors:

  1. context error: canceled or deadline exceeded.
  2. gRPC error: see https://etcd/blob/master/etcdserver/api/v3rpc/rpctypes/error.go

Here is the example code to handle client errors: 

resp, err := kvc.Put(ctx, "", "")
if err != nil {
	if err == context.Canceled {
		// ctx is canceled by another routine
	} else if err == context.DeadlineExceeded {
		// ctx is attached with a deadline and it exceeded
	} else if verr, ok := err.(*v3rpc.ErrEmptyKey); ok {
		// process (verr.Errors)
	} else {
		// bad cluster endpoints, which are not etcd servers
	}
}
Example 
package main

import (
	"log"
	"time"

	"context"
	"etcd/clientv3"
	"github.com/coreos/pkg/capnslog"
)

var (
	dialTimeout = 5 * time.Second

	endpoints = []string{"localhost:2379", "localhost:22379", "localhost:32379"}
)

func main() {
	var plog = capnslog.NewPackageLogger("etcd", "clientv3")
	clientv3.SetLogger(plog)

	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close() // make sure to close the client

	_, err = cli.Put(context.TODO(), "foo", "bar")
	if err != nil {
		log.Fatal(err)
	}
}

Output:

Index

Examples

Constants

View Source 
const (
	PermRead      = authpb.READ
	PermWrite     = authpb.WRITE
	PermReadWrite = authpb.READWRITE
)
View Source 
const (
	EventTypeDelete = mvccpb.DELETE
	EventTypePut    = mvccpb.PUT
)

Variables

View Source 
var ErrNoAddrAvilable = grpc.Errorf(codes.Unavailable, "there is no address available")

ErrNoAddrAvilable is returned by Get() when the balancer does not have any active connection to endpoints at the time. This error is returned only when opts.BlockingWait is true.

View Source 
var (
	ErrNoAvailableEndpoints = errors.New("etcdclient: no available endpoints")
)

Functions

func GetPrefixRangeEnd 

func GetPrefixRangeEnd(prefix string) string

GetPrefixRangeEnd gets the range end of the prefix. 'Get(foo, WithPrefix())' is equal to 'Get(foo, WithRange(GetPrefixRangeEnd(foo))'.

func RetryAuthClient 

func RetryAuthClient(c *Client) pb.AuthClient

RetryAuthClient implements a AuthClient that uses the client's FailFast retry policy.

func RetryClusterClient 

func RetryClusterClient(c *Client) pb.ClusterClient

RetryClusterClient implements a ClusterClient that uses the client's FailFast retry policy.

func RetryKVClient 

func RetryKVClient(c *Client) pb.KVClient

RetryKVClient implements a KVClient that uses the client's FailFast retry policy.

func RetryLeaseClient 

func RetryLeaseClient(c *Client) pb.LeaseClient

RetryLeaseClient implements a LeaseClient that uses the client's FailFast retry policy.

func SetLogger 

func SetLogger(l Logger)

SetLogger sets client-side Logger. By default, logs are disabled.

func WithRequireLeader 

func WithRequireLeader(ctx context.Context) context.Context

WithRequireLeader requires client requests to only succeed when the cluster has a leader.

Types

type AlarmMember 

type AlarmMember pb.AlarmMember

type AlarmResponse 

type AlarmResponse pb.AlarmResponse

type Auth 

type Auth interface {
	// AuthEnable enables auth of an etcd cluster.
	AuthEnable(ctx context.Context) (*AuthEnableResponse, error)

	// AuthDisable disables auth of an etcd cluster.
	AuthDisable(ctx context.Context) (*AuthDisableResponse, error)

	// UserAdd adds a new user to an etcd cluster.
	UserAdd(ctx context.Context, name string, password string) (*AuthUserAddResponse, error)

	// UserDelete deletes a user from an etcd cluster.
	UserDelete(ctx context.Context, name string) (*AuthUserDeleteResponse, error)

	// UserChangePassword changes a password of a user.
	UserChangePassword(ctx context.Context, name string, password string) (*AuthUserChangePasswordResponse, error)

	// UserGrantRole grants a role to a user.
	UserGrantRole(ctx context.Context, user string, role string) (*AuthUserGrantRoleResponse, error)

	// UserGet gets a detailed information of a user.
	UserGet(ctx context.Context, name string) (*AuthUserGetResponse, error)

	// UserList gets a list of all users.
	UserList(ctx context.Context) (*AuthUserListResponse, error)

	// UserRevokeRole revokes a role of a user.
	UserRevokeRole(ctx context.Context, name string, role string) (*AuthUserRevokeRoleResponse, error)

	// RoleAdd adds a new role to an etcd cluster.
	RoleAdd(ctx context.Context, name string) (*AuthRoleAddResponse, error)

	// RoleGrantPermission grants a permission to a role.
	RoleGrantPermission(ctx context.Context, name string, key, rangeEnd string, permType PermissionType) (*AuthRoleGrantPermissionResponse, error)

	// RoleGet gets a detailed information of a role.
	RoleGet(ctx context.Context, role string) (*AuthRoleGetResponse, error)

	// RoleList gets a list of all roles.
	RoleList(ctx context.Context) (*AuthRoleListResponse, error)

	// RoleRevokePermission revokes a permission from a role.
	RoleRevokePermission(ctx context.Context, role string, key, rangeEnd string) (*AuthRoleRevokePermissionResponse, error)

	// RoleDelete deletes a role.
	RoleDelete(ctx context.Context, role string) (*AuthRoleDeleteResponse, error)
}
Example 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

if _, err = cli.RoleAdd(context.TODO(), "root"); err != nil {
	log.Fatal(err)
}
if _, err = cli.UserAdd(context.TODO(), "root", "123"); err != nil {
	log.Fatal(err)
}
if _, err = cli.UserGrantRole(context.TODO(), "root", "root"); err != nil {
	log.Fatal(err)
}

if _, err = cli.RoleAdd(context.TODO(), "r"); err != nil {
	log.Fatal(err)
}

if _, err = cli.RoleGrantPermission(
	context.TODO(),
	"r",   // role name
	"foo", // key
	"zoo", // range end
	clientv3.PermissionType(clientv3.PermReadWrite),
); err != nil {
	log.Fatal(err)
}
if _, err = cli.UserAdd(context.TODO(), "u", "123"); err != nil {
	log.Fatal(err)
}
if _, err = cli.UserGrantRole(context.TODO(), "u", "r"); err != nil {
	log.Fatal(err)
}
if _, err = cli.AuthEnable(context.TODO()); err != nil {
	log.Fatal(err)
}

cliAuth, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
	Username:    "u",
	Password:    "123",
})
if err != nil {
	log.Fatal(err)
}
defer cliAuth.Close()

if _, err = cliAuth.Put(context.TODO(), "foo1", "bar"); err != nil {
	log.Fatal(err)
}

_, err = cliAuth.Txn(context.TODO()).
	If(clientv3.Compare(clientv3.Value("zoo1"), ">", "abc")).
	Then(clientv3.OpPut("zoo1", "XYZ")).
	Else(clientv3.OpPut("zoo1", "ABC")).
	Commit()
fmt.Println(err)

// now check the permission with the root account
rootCli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
	Username:    "root",
	Password:    "123",
})
if err != nil {
	log.Fatal(err)
}
defer rootCli.Close()

resp, err := rootCli.RoleGet(context.TODO(), "r")
if err != nil {
	log.Fatal(err)
}
fmt.Printf("user u permission: key %q, range end %q\n", resp.Perm[0].Key, resp.Perm[0].RangeEnd)

if _, err = rootCli.AuthDisable(context.TODO()); err != nil {
	log.Fatal(err)
}

Output:

etcdserver: permission denied
user u permission: key "foo", range end "zoo"

func NewAuth 

func NewAuth(c *Client) Auth

type AuthDisableResponse 

type AuthDisableResponse pb.AuthDisableResponse

type AuthEnableResponse 

type AuthEnableResponse pb.AuthEnableResponse

type AuthRoleAddResponse 

type AuthRoleAddResponse pb.AuthRoleAddResponse

type AuthRoleDeleteResponse 

type AuthRoleDeleteResponse pb.AuthRoleDeleteResponse

type AuthRoleGetResponse 

type AuthRoleGetResponse pb.AuthRoleGetResponse

type AuthRoleGrantPermissionResponse 

type AuthRoleGrantPermissionResponse pb.AuthRoleGrantPermissionResponse

type AuthRoleListResponse 

type AuthRoleListResponse pb.AuthRoleListResponse

type AuthRoleRevokePermissionResponse 

type AuthRoleRevokePermissionResponse pb.AuthRoleRevokePermissionResponse

type AuthUserAddResponse 

type AuthUserAddResponse pb.AuthUserAddResponse

type AuthUserChangePasswordResponse 

type AuthUserChangePasswordResponse pb.AuthUserChangePasswordResponse

type AuthUserDeleteResponse 

type AuthUserDeleteResponse pb.AuthUserDeleteResponse

type AuthUserGetResponse 

type AuthUserGetResponse pb.AuthUserGetResponse

type AuthUserGrantRoleResponse 

type AuthUserGrantRoleResponse pb.AuthUserGrantRoleResponse

type AuthUserListResponse 

type AuthUserListResponse pb.AuthUserListResponse

type AuthUserRevokeRoleResponse 

type AuthUserRevokeRoleResponse pb.AuthUserRevokeRoleResponse

type AuthenticateResponse 

type AuthenticateResponse pb.AuthenticateResponse

type Client 

type Client struct {
	Cluster
	KV
	Lease
	Watcher
	Auth
	Maintenance

	// Username is a username for authentication
	Username string
	// Password is a password for authentication
	Password string
	// contains filtered or unexported fields
}

Client provides and manages an etcd v3 client session.

func New 

func New(cfg Config) (*Client, error)

New creates a new etcdv3 client from a given configuration.

func NewFromConfigFile 

func NewFromConfigFile(path string) (*Client, error)

NewFromConfigFile creates a new etcdv3 client from a configuration file.

func NewFromURL 

func NewFromURL(url string) (*Client, error)

NewFromURL creates a new etcdv3 client from a URL.

func (*Client) ActiveConnection 

func (c *Client) ActiveConnection() *grpc.ClientConn

ActiveConnection returns the current in-use connection

func (*Client) Close 

func (c *Client) Close() error

Close shuts down the client's etcd connections.

func (*Client) Ctx 

func (c *Client) Ctx() context.Context

Ctx is a context for "out of band" messages (e.g., for sending "clean up" message when another context is canceled). It is canceled on client Close().

func (*Client) Dial 

func (c *Client) Dial(endpoint string) (*grpc.ClientConn, error)

Dial connects to a single endpoint using the client's config.

func (*Client) Endpoints 

func (c *Client) Endpoints() (eps []string)

Endpoints lists the registered endpoints for the client.

func (*Client) SetEndpoints 

func (c *Client) SetEndpoints(eps ...string)

SetEndpoints updates client's endpoints.

func (*Client) Sync 

func (c *Client) Sync(ctx context.Context) error

Sync synchronizes client's endpoints with the known endpoints from the etcd membership.

type Cluster 

type Cluster interface {
	// MemberList lists the current cluster membership.
	MemberList(ctx context.Context) (*MemberListResponse, error)

	// MemberAdd adds a new member into the cluster.
	MemberAdd(ctx context.Context, peerAddrs []string) (*MemberAddResponse, error)

	// MemberRemove removes an existing member from the cluster.
	MemberRemove(ctx context.Context, id uint64) (*MemberRemoveResponse, error)

	// MemberUpdate updates the peer addresses of the member.
	MemberUpdate(ctx context.Context, id uint64, peerAddrs []string) (*MemberUpdateResponse, error)
}
Example (MemberAdd) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints[:2],
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

peerURLs := endpoints[2:]
mresp, err := cli.MemberAdd(context.Background(), peerURLs)
if err != nil {
	log.Fatal(err)
}
fmt.Println("added member.PeerURLs:", mresp.Member.PeerURLs)
// added member.PeerURLs: [http://localhost:32380]

Output:
Example (MemberList) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

resp, err := cli.MemberList(context.Background())
if err != nil {
	log.Fatal(err)
}
fmt.Println("members:", len(resp.Members))

Output:

members: 3
Example (MemberRemove) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints[1:],
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

resp, err := cli.MemberList(context.Background())
if err != nil {
	log.Fatal(err)
}

_, err = cli.MemberRemove(context.Background(), resp.Members[0].ID)
if err != nil {
	log.Fatal(err)
}

Output:
Example (MemberUpdate) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

resp, err := cli.MemberList(context.Background())
if err != nil {
	log.Fatal(err)
}

peerURLs := []string{"http://localhost:12380"}
_, err = cli.MemberUpdate(context.Background(), resp.Members[0].ID, peerURLs)
if err != nil {
	log.Fatal(err)
}

Output:

func NewCluster 

func NewCluster(c *Client) Cluster

type Cmp 

type Cmp pb.Compare

func Compare 

func Compare(cmp Cmp, result string, v interface{}) Cmp

func CreateRevision 

func CreateRevision(key string) Cmp

func ModRevision 

func ModRevision(key string) Cmp

func Value 

func Value(key string) Cmp

func Version 

func Version(key string) Cmp

type CompactOp 

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

CompactOp represents a compact operation.

func OpCompact 

func OpCompact(rev int64, opts ...CompactOption) CompactOp

OpCompact wraps slice CompactOption to create a CompactOp.

type CompactOption 

type CompactOption func(*CompactOp)

CompactOption configures compact operation.

func WithCompactPhysical 

func WithCompactPhysical() CompactOption

WithCompactPhysical makes compact RPC call wait until the compaction is physically applied to the local database such that compacted entries are totally removed from the backend database.

type CompactResponse 

type CompactResponse pb.CompactionResponse

type CompareResult 

type CompareResult int

type CompareTarget 

type CompareTarget int
const (
	CompareVersion CompareTarget = iota
	CompareCreated
	CompareModified
	CompareValue
)

type Config 

type Config struct {
	// Endpoints is a list of URLs
	Endpoints []string

	// AutoSyncInterval is the interval to update endpoints with its latest members.
	// 0 disables auto-sync. By default auto-sync is disabled.
	AutoSyncInterval time.Duration

	// DialTimeout is the timeout for failing to establish a connection.
	DialTimeout time.Duration

	// TLS holds the client secure credentials, if any.
	TLS *tls.Config

	// Username is a username for authentication
	Username string

	// Password is a password for authentication
	Password string
}
Example (WithTLS) 
package main

import (
	"log"
	"time"

	"context"
	"etcd/clientv3"
	"etcd/pkg/transport"
)

var (
	dialTimeout = 5 * time.Second

	endpoints = []string{"localhost:2379", "localhost:22379", "localhost:32379"}
)

func main() {
	tlsInfo := transport.TLSInfo{
		CertFile:      "/tmp/test-certs/test-name-1.pem",
		KeyFile:       "/tmp/test-certs/test-name-1-key.pem",
		TrustedCAFile: "/tmp/test-certs/trusted-ca.pem",
	}
	tlsConfig, err := tlsInfo.ClientConfig()
	if err != nil {
		log.Fatal(err)
	}
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   endpoints,
		DialTimeout: dialTimeout,
		TLS:         tlsConfig,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close() // make sure to close the client

	_, err = cli.Put(context.TODO(), "foo", "bar")
	if err != nil {
		log.Fatal(err)
	}
}

Output:

type DefragmentResponse 

type DefragmentResponse pb.DefragmentResponse

type DeleteResponse 

type DeleteResponse pb.DeleteRangeResponse

type ErrKeepAliveHalted 

type ErrKeepAliveHalted struct {
	Reason error
}

ErrKeepAliveHalted is returned if client keep alive loop halts with an unexpected error.

This usually means that automatic lease renewal via KeepAlive is broken, but KeepAliveOnce will still work as expected.

func (ErrKeepAliveHalted) Error 

func (e ErrKeepAliveHalted) Error() string

type Event 

type Event mvccpb.Event

func (*Event) IsCreate 

func (e *Event) IsCreate() bool

IsCreate returns true if the event tells that the key is newly created.

func (*Event) IsModify 

func (e *Event) IsModify() bool

IsModify returns true if the event tells that a new value is put on existing key.

type GetResponse 

type GetResponse pb.RangeResponse

type KV 

type KV interface {
	// Put puts a key-value pair into etcd.
	// Note that key,value can be plain bytes array and string is
	// an immutable representation of that bytes array.
	// To get a string of bytes, do string([]byte(0x10, 0x20)).
	Put(ctx context.Context, key, val string, opts ...OpOption) (*PutResponse, error)

	// Get retrieves keys.
	// By default, Get will return the value for "key", if any.
	// When passed WithRange(end), Get will return the keys in the range [key, end).
	// When passed WithFromKey(), Get returns keys greater than or equal to key.
	// When passed WithRev(rev) with rev > 0, Get retrieves keys at the given revision;
	// if the required revision is compacted, the request will fail with ErrCompacted .
	// When passed WithLimit(limit), the number of returned keys is bounded by limit.
	// When passed WithSort(), the keys will be sorted.
	Get(ctx context.Context, key string, opts ...OpOption) (*GetResponse, error)

	// Delete deletes a key, or optionally using WithRange(end), [key, end).
	Delete(ctx context.Context, key string, opts ...OpOption) (*DeleteResponse, error)

	// Compact compacts etcd KV history before the given rev.
	Compact(ctx context.Context, rev int64, opts ...CompactOption) (*CompactResponse, error)

	// Do applies a single Op on KV without a transaction.
	// Do is useful when creating arbitrary operations to be issued at a
	// later time; the user can range over the operations, calling Do to
	// execute them. Get/Put/Delete, on the other hand, are best suited
	// for when the operation should be issued at the time of declaration.
	Do(ctx context.Context, op Op) (OpResponse, error)

	// Txn creates a transaction.
	Txn(ctx context.Context) Txn
}
Example (Compact) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
resp, err := cli.Get(ctx, "foo")
cancel()
if err != nil {
	log.Fatal(err)
}
compRev := resp.Header.Revision // specify compact revision of your choice

ctx, cancel = context.WithTimeout(context.Background(), requestTimeout)
_, err = cli.Compact(ctx, compRev)
cancel()
if err != nil {
	log.Fatal(err)
}

Output:
Example (Delete) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
defer cancel()

// count keys about to be deleted
gresp, err := cli.Get(ctx, "key", clientv3.WithPrefix())
if err != nil {
	log.Fatal(err)
}

// delete the keys
dresp, err := cli.Delete(ctx, "key", clientv3.WithPrefix())
if err != nil {
	log.Fatal(err)
}

fmt.Println("Deleted all keys:", int64(len(gresp.Kvs)) == dresp.Deleted)

Output:

Deleted all keys: true
Example (Do) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

ops := []clientv3.Op{
	clientv3.OpPut("put-key", "123"),
	clientv3.OpGet("put-key"),
	clientv3.OpPut("put-key", "456")}

for _, op := range ops {
	if _, err := cli.Do(context.TODO(), op); err != nil {
		log.Fatal(err)
	}
}

Output:
Example (Get) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

_, err = cli.Put(context.TODO(), "foo", "bar")
if err != nil {
	log.Fatal(err)
}

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
resp, err := cli.Get(ctx, "foo")
cancel()
if err != nil {
	log.Fatal(err)
}
for _, ev := range resp.Kvs {
	fmt.Printf("%s : %s\n", ev.Key, ev.Value)
}

Output:

foo : bar
Example (GetSortedPrefix) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

for i := range make([]int, 3) {
	ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
	_, err = cli.Put(ctx, fmt.Sprintf("key_%d", i), "value")
	cancel()
	if err != nil {
		log.Fatal(err)
	}
}

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
resp, err := cli.Get(ctx, "key", clientv3.WithPrefix(), clientv3.WithSort(clientv3.SortByKey, clientv3.SortDescend))
cancel()
if err != nil {
	log.Fatal(err)
}
for _, ev := range resp.Kvs {
	fmt.Printf("%s : %s\n", ev.Key, ev.Value)
}

Output:

key_2 : value
key_1 : value
key_0 : value
Example (GetWithRev) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

presp, err := cli.Put(context.TODO(), "foo", "bar1")
if err != nil {
	log.Fatal(err)
}
_, err = cli.Put(context.TODO(), "foo", "bar2")
if err != nil {
	log.Fatal(err)
}

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
resp, err := cli.Get(ctx, "foo", clientv3.WithRev(presp.Header.Revision))
cancel()
if err != nil {
	log.Fatal(err)
}
for _, ev := range resp.Kvs {
	fmt.Printf("%s : %s\n", ev.Key, ev.Value)
}

Output:

foo : bar1
Example (Put) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
_, err = cli.Put(ctx, "sample_key", "sample_value")
cancel()
if err != nil {
	log.Fatal(err)
}

Output:
Example (PutErrorHandling) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
_, err = cli.Put(ctx, "", "sample_value")
cancel()
if err != nil {
	switch err {
	case context.Canceled:
		fmt.Printf("ctx is canceled by another routine: %v\n", err)
	case context.DeadlineExceeded:
		fmt.Printf("ctx is attached with a deadline is exceeded: %v\n", err)
	case rpctypes.ErrEmptyKey:
		fmt.Printf("client-side error: %v\n", err)
	default:
		fmt.Printf("bad cluster endpoints, which are not etcd servers: %v\n", err)
	}
}

Output:

client-side error: etcdserver: key is not provided
Example (Txn) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

kvc := clientv3.NewKV(cli)

_, err = kvc.Put(context.TODO(), "key", "xyz")
if err != nil {
	log.Fatal(err)
}

ctx, cancel := context.WithTimeout(context.Background(), requestTimeout)
_, err = kvc.Txn(ctx).
	If(clientv3.Compare(clientv3.Value("key"), ">", "abc")). // txn value comparisons are lexical
	Then(clientv3.OpPut("key", "XYZ")).                      // this runs, since 'xyz' > 'abc'
	Else(clientv3.OpPut("key", "ABC")).
	Commit()
cancel()
if err != nil {
	log.Fatal(err)
}

gresp, err := kvc.Get(context.TODO(), "key")
cancel()
if err != nil {
	log.Fatal(err)
}
for _, ev := range gresp.Kvs {
	fmt.Printf("%s : %s\n", ev.Key, ev.Value)
}

Output:

key : XYZ

func NewKV 

func NewKV(c *Client) KV

func NewKVFromKVClient 

func NewKVFromKVClient(remote pb.KVClient) KV

type Lease 

type Lease interface {
	// Grant creates a new lease.
	Grant(ctx context.Context, ttl int64) (*LeaseGrantResponse, error)

	// Revoke revokes the given lease.
	Revoke(ctx context.Context, id LeaseID) (*LeaseRevokeResponse, error)

	// TimeToLive retrieves the lease information of the given lease ID.
	TimeToLive(ctx context.Context, id LeaseID, opts ...LeaseOption) (*LeaseTimeToLiveResponse, error)

	// KeepAlive keeps the given lease alive forever.
	KeepAlive(ctx context.Context, id LeaseID) (<-chan *LeaseKeepAliveResponse, error)

	// KeepAliveOnce renews the lease once. In most of the cases, Keepalive
	// should be used instead of KeepAliveOnce.
	KeepAliveOnce(ctx context.Context, id LeaseID) (*LeaseKeepAliveResponse, error)

	// Close releases all resources Lease keeps for efficient communication
	// with the etcd server.
	Close() error
}
Example (Grant) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

// minimum lease TTL is 5-second
resp, err := cli.Grant(context.TODO(), 5)
if err != nil {
	log.Fatal(err)
}

// after 5 seconds, the key 'foo' will be removed
_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(resp.ID))
if err != nil {
	log.Fatal(err)
}

Output:
Example (KeepAlive) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

resp, err := cli.Grant(context.TODO(), 5)
if err != nil {
	log.Fatal(err)
}

_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(resp.ID))
if err != nil {
	log.Fatal(err)
}

// the key 'foo' will be kept forever
ch, kaerr := cli.KeepAlive(context.TODO(), resp.ID)
if kaerr != nil {
	log.Fatal(kaerr)
}

ka := <-ch
fmt.Println("ttl:", ka.TTL)

Output:

ttl: 5
Example (KeepAliveOnce) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

resp, err := cli.Grant(context.TODO(), 5)
if err != nil {
	log.Fatal(err)
}

_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(resp.ID))
if err != nil {
	log.Fatal(err)
}

// to renew the lease only once
ka, kaerr := cli.KeepAliveOnce(context.TODO(), resp.ID)
if kaerr != nil {
	log.Fatal(kaerr)
}

fmt.Println("ttl:", ka.TTL)

Output:

ttl: 5
Example (Revoke) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

resp, err := cli.Grant(context.TODO(), 5)
if err != nil {
	log.Fatal(err)
}

_, err = cli.Put(context.TODO(), "foo", "bar", clientv3.WithLease(resp.ID))
if err != nil {
	log.Fatal(err)
}

// revoking lease expires the key attached to its lease ID
_, err = cli.Revoke(context.TODO(), resp.ID)
if err != nil {
	log.Fatal(err)
}

gresp, err := cli.Get(context.TODO(), "foo")
if err != nil {
	log.Fatal(err)
}
fmt.Println("number of keys:", len(gresp.Kvs))

Output:

number of keys: 0

func NewLease 

func NewLease(c *Client) Lease

type LeaseGrantResponse 

type LeaseGrantResponse struct {
	*pb.ResponseHeader
	ID    LeaseID
	TTL   int64
	Error string
}

LeaseGrantResponse is used to convert the protobuf grant response.

type LeaseID 

type LeaseID int64
const (

	// NoLease is a lease ID for the absence of a lease.
	NoLease LeaseID = 0
)

type LeaseKeepAliveResponse 

type LeaseKeepAliveResponse struct {
	*pb.ResponseHeader
	ID  LeaseID
	TTL int64
}

LeaseKeepAliveResponse is used to convert the protobuf keepalive response.

type LeaseOp 

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

LeaseOp represents an Operation that lease can execute.

type LeaseOption 

type LeaseOption func(*LeaseOp)

LeaseOption configures lease operations.

func WithAttachedKeys 

func WithAttachedKeys() LeaseOption

WithAttachedKeys requests lease timetolive API to return attached keys of given lease ID.

type LeaseRevokeResponse 

type LeaseRevokeResponse pb.LeaseRevokeResponse

type LeaseTimeToLiveResponse 

type LeaseTimeToLiveResponse struct {
	*pb.ResponseHeader
	ID LeaseID `json:"id"`

	// TTL is the remaining TTL in seconds for the lease; the lease will expire in under TTL+1 seconds.
	TTL int64 `json:"ttl"`

	// GrantedTTL is the initial granted time in seconds upon lease creation/renewal.
	GrantedTTL int64 `json:"granted-ttl"`

	// Keys is the list of keys attached to this lease.
	Keys [][]byte `json:"keys"`
}

LeaseTimeToLiveResponse is used to convert the protobuf lease timetolive response.

type Logger 

type Logger grpclog.Logger

Logger is the logger used by client library. It implements grpclog.Logger interface.

func GetLogger 

func GetLogger() Logger

GetLogger returns the current logger.

type Maintenance 

type Maintenance interface {
	// AlarmList gets all active alarms.
	AlarmList(ctx context.Context) (*AlarmResponse, error)

	// AlarmDisarm disarms a given alarm.
	AlarmDisarm(ctx context.Context, m *AlarmMember) (*AlarmResponse, error)

	// Defragment defragments storage backend of the etcd member with given endpoint.
	// Defragment is only needed when deleting a large number of keys and want to reclaim
	// the resources.
	// Defragment is an expensive operation. User should avoid defragmenting multiple members
	// at the same time.
	// To defragment multiple members in the cluster, user need to call defragment multiple
	// times with different endpoints.
	Defragment(ctx context.Context, endpoint string) (*DefragmentResponse, error)

	// Status gets the status of the endpoint.
	Status(ctx context.Context, endpoint string) (*StatusResponse, error)

	// Snapshot provides a reader for a snapshot of a backend.
	Snapshot(ctx context.Context) (io.ReadCloser, error)
}
Example (Defragment) 
for _, ep := range endpoints {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   []string{ep},
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	if _, err = cli.Defragment(context.TODO(), ep); err != nil {
		log.Fatal(err)
	}
}

Output:
Example (Status) 
for _, ep := range endpoints {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   []string{ep},
		DialTimeout: dialTimeout,
	})
	if err != nil {
		log.Fatal(err)
	}
	defer cli.Close()

	// resp, err := cli.Status(context.Background(), ep)
	//
	// or
	//
	mapi := clientv3.NewMaintenance(cli)
	resp, err := mapi.Status(context.Background(), ep)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("endpoint: %s / IsLeader: %v\n", ep, resp.Header.MemberId == resp.Leader)
}
// endpoint: localhost:2379 / IsLeader: false
// endpoint: localhost:22379 / IsLeader: false
// endpoint: localhost:32379 / IsLeader: true

Output:

func NewMaintenance 

func NewMaintenance(c *Client) Maintenance

type Member 

type Member pb.Member

type MemberAddResponse 

type MemberAddResponse pb.MemberAddResponse

type MemberListResponse 

type MemberListResponse pb.MemberListResponse

type MemberRemoveResponse 

type MemberRemoveResponse pb.MemberRemoveResponse

type MemberUpdateResponse 

type MemberUpdateResponse pb.MemberUpdateResponse

type Op 

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

Op represents an Operation that kv can execute.

func OpDelete 

func OpDelete(key string, opts ...OpOption) Op

func OpGet 

func OpGet(key string, opts ...OpOption) Op

func OpPut 

func OpPut(key, val string, opts ...OpOption) Op

type OpOption 

type OpOption func(*Op)

OpOption configures Operations like Get, Put, Delete.

func WithCountOnly 

func WithCountOnly() OpOption

WithCountOnly makes the 'Get' request return only the count of keys.

func WithCreatedNotify 

func WithCreatedNotify() OpOption

WithCreatedNotify makes watch server sends the created event.

func WithFilterDelete 

func WithFilterDelete() OpOption

WithFilterDelete discards DELETE events from the watcher.

func WithFilterPut 

func WithFilterPut() OpOption

WithFilterPut discards PUT events from the watcher.

func WithFirstCreate 

func WithFirstCreate() []OpOption

WithFirstCreate gets the key with the oldest creation revision in the request range.

func WithFirstKey 

func WithFirstKey() []OpOption

WithFirstKey gets the lexically first key in the request range.

func WithFirstRev 

func WithFirstRev() []OpOption

WithFirstRev gets the key with the oldest modification revision in the request range.

func WithFromKey 

func WithFromKey() OpOption

WithFromKey specifies the range of 'Get', 'Delete', 'Watch' requests to be equal or greater than the key in the argument.

func WithKeysOnly 

func WithKeysOnly() OpOption

WithKeysOnly makes the 'Get' request return only the keys and the corresponding values will be omitted.

func WithLastCreate 

func WithLastCreate() []OpOption

WithLastCreate gets the key with the latest creation revision in the request range.

func WithLastKey 

func WithLastKey() []OpOption

WithLastKey gets the lexically last key in the request range.

func WithLastRev 

func WithLastRev() []OpOption

WithLastRev gets the key with the latest modification revision in the request range.

func WithLease 

func WithLease(leaseID LeaseID) OpOption

WithLease attaches a lease ID to a key in 'Put' request.

func WithLimit 

func WithLimit(n int64) OpOption

WithLimit limits the number of results to return from 'Get' request.

func WithMaxCreateRev 

func WithMaxCreateRev(rev int64) OpOption

WithMaxCreateRev filters out keys for Get with creation revisions greater than the given revision.

func WithMaxModRev 

func WithMaxModRev(rev int64) OpOption

WithMaxModRev filters out keys for Get with modification revisions greater than the given revision.

func WithMinCreateRev 

func WithMinCreateRev(rev int64) OpOption

WithMinCreateRev filters out keys for Get with creation revisions less than the given revision.

func WithMinModRev 

func WithMinModRev(rev int64) OpOption

WithMinModRev filters out keys for Get with modification revisions less than the given revision.

func WithPrefix 

func WithPrefix() OpOption

WithPrefix enables 'Get', 'Delete', or 'Watch' requests to operate on the keys with matching prefix. For example, 'Get(foo, WithPrefix())' can return 'foo1', 'foo2', and so on.

func WithPrevKV 

func WithPrevKV() OpOption

WithPrevKV gets the previous key-value pair before the event happens. If the previous KV is already compacted, nothing will be returned.

func WithProgressNotify 

func WithProgressNotify() OpOption

WithProgressNotify makes watch server send periodic progress updates every 10 minutes when there is no incoming events. Progress updates have zero events in WatchResponse.

func WithRange 

func WithRange(endKey string) OpOption

WithRange specifies the range of 'Get', 'Delete', 'Watch' requests. For example, 'Get' requests with 'WithRange(end)' returns the keys in the range [key, end). endKey must be lexicographically greater than start key.

func WithRev 

func WithRev(rev int64) OpOption

WithRev specifies the store revision for 'Get' request. Or the start revision of 'Watch' request.

func WithSerializable 

func WithSerializable() OpOption

WithSerializable makes 'Get' request serializable. By default, it's linearizable. Serializable requests are better for lower latency requirement.

func WithSort 

func WithSort(target SortTarget, order SortOrder) OpOption

WithSort specifies the ordering in 'Get' request. It requires 'WithRange' and/or 'WithPrefix' to be specified too. 'target' specifies the target to sort by: key, version, revisions, value. 'order' can be either 'SortNone', 'SortAscend', 'SortDescend'.

type OpResponse 

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

func (OpResponse) Del 

func (op OpResponse) Del() *DeleteResponse

func (OpResponse) Get 

func (op OpResponse) Get() *GetResponse

func (OpResponse) Put 

func (op OpResponse) Put() *PutResponse

type Permission 

type Permission authpb.Permission

type PermissionType 

type PermissionType authpb.Permission_Type

func StrToPermissionType 

func StrToPermissionType(s string) (PermissionType, error)

type PutResponse 

type PutResponse pb.PutResponse

type SortOption 

type SortOption struct {
	Target SortTarget
	Order  SortOrder
}

type SortOrder 

type SortOrder int
const (
	SortNone SortOrder = iota
	SortAscend
	SortDescend
)

type SortTarget 

type SortTarget int
const (
	SortByKey SortTarget = iota
	SortByVersion
	SortByCreateRevision
	SortByModRevision
	SortByValue
)

type StatusResponse 

type StatusResponse pb.StatusResponse

type Txn 

type Txn interface {
	// If takes a list of comparison. If all comparisons passed in succeed,
	// the operations passed into Then() will be executed. Or the operations
	// passed into Else() will be executed.
	If(cs ...Cmp) Txn

	// Then takes a list of operations. The Ops list will be executed, if the
	// comparisons passed in If() succeed.
	Then(ops ...Op) Txn

	// Else takes a list of operations. The Ops list will be executed, if the
	// comparisons passed in If() fail.
	Else(ops ...Op) Txn

	// Commit tries to commit the transaction.
	Commit() (*TxnResponse, error)
}

Txn is the interface that wraps mini-transactions. 

Tx.If(
 Compare(Value(k1), ">", v1),
 Compare(Version(k1), "=", 2)
).Then(
 OpPut(k2,v2), OpPut(k3,v3)
).Else(
 OpPut(k4,v4), OpPut(k5,v5)
).Commit()

type TxnResponse 

type TxnResponse pb.TxnResponse

type WatchChan 

type WatchChan <-chan WatchResponse

type WatchResponse 

type WatchResponse struct {
	Header pb.ResponseHeader
	Events []*Event

	// CompactRevision is the minimum revision the watcher may receive.
	CompactRevision int64

	// Canceled is used to indicate watch failure.
	// If the watch failed and the stream was about to close, before the channel is closed,
	// the channel sends a final response that has Canceled set to true with a non-nil Err().
	Canceled bool

	// Created is used to indicate the creation of the watcher.
	Created bool
	// contains filtered or unexported fields
}

func (*WatchResponse) Err 

func (wr *WatchResponse) Err() error

Err is the error value if this WatchResponse holds an error.

func (*WatchResponse) IsProgressNotify 

func (wr *WatchResponse) IsProgressNotify() bool

IsProgressNotify returns true if the WatchResponse is progress notification.

type Watcher 

type Watcher interface {
	// Watch watches on a key or prefix. The watched events will be returned
	// through the returned channel.
	// If the watch is slow or the required rev is compacted, the watch request
	// might be canceled from the server-side and the chan will be closed.
	// 'opts' can be: 'WithRev' and/or 'WithPrefix'.
	Watch(ctx context.Context, key string, opts ...OpOption) WatchChan

	// Close closes the watcher and cancels all watch requests.
	Close() error
}
Example (Watch) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

rch := cli.Watch(context.Background(), "foo")
for wresp := range rch {
	for _, ev := range wresp.Events {
		fmt.Printf("%s %q : %q\n", ev.Type, ev.Kv.Key, ev.Kv.Value)
	}
}
// PUT "foo" : "bar"

Output:
Example (WatchWithPrefix) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

rch := cli.Watch(context.Background(), "foo", clientv3.WithPrefix())
for wresp := range rch {
	for _, ev := range wresp.Events {
		fmt.Printf("%s %q : %q\n", ev.Type, ev.Kv.Key, ev.Kv.Value)
	}
}
// PUT "foo1" : "bar"

Output:
Example (WatchWithProgressNotify) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}

rch := cli.Watch(context.Background(), "foo", clientv3.WithProgressNotify())
wresp := <-rch
fmt.Printf("wresp.Header.Revision: %d\n", wresp.Header.Revision)
fmt.Println("wresp.IsProgressNotify:", wresp.IsProgressNotify())
// wresp.Header.Revision: 0
// wresp.IsProgressNotify: true

Output:
Example (WatchWithRange) 
cli, err := clientv3.New(clientv3.Config{
	Endpoints:   endpoints,
	DialTimeout: dialTimeout,
})
if err != nil {
	log.Fatal(err)
}
defer cli.Close()

// watches within ['foo1', 'foo4'), in lexicographical order
rch := cli.Watch(context.Background(), "foo1", clientv3.WithRange("foo4"))
for wresp := range rch {
	for _, ev := range wresp.Events {
		fmt.Printf("%s %q : %q\n", ev.Type, ev.Kv.Key, ev.Kv.Value)
	}
}
// PUT "foo1" : "bar"
// PUT "foo2" : "bar"
// PUT "foo3" : "bar"

Output:

func NewWatchFromWatchClient 

func NewWatchFromWatchClient(wc pb.WatchClient) Watcher

func NewWatcher 

func NewWatcher(c *Client) Watcher

Source Files

View all Source files

Directories

Path Synopsis
Package concurrency implements concurrency operations on top of etcd such as distributed locks, barriers, and elections.
 Package concurrency implements concurrency operations on top of etcd such as distributed locks, barriers, and elections.
Package integration implements tests built upon embedded etcd, and focuses on correctness of etcd client.
 Package integration implements tests built upon embedded etcd, and focuses on correctness of etcd client.
Package mirror implements etcd mirroring operations.
 Package mirror implements etcd mirroring operations.

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