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谁借莪１个温暖的怀抱￠ 2021-09-01 03:15 379阅读 0赞

# etcdctl #

`etcdctl` is a command line client for [etcd][].  
It can be used in scripts or for administrators to explore an etcd cluster.

## Getting etcdctl ##

The latest release is available as a binary at [Github][] along with etcd.

etcdctl can also be built from source using the build script found in the parent directory.

## Configuration ##

### –debug ###

*  output cURL commands which can be used to reproduce the request

### –no-sync ###

*  don’t synchronize cluster information before sending request
 *  Use this to access non-published client endpoints
 *  Without this flag, values from `--endpoint` flag will be overwritten by etcd cluster when it does internal sync.

### –output, -o ###

*  output response in the given format (`simple`, `extended` or `json`)
 *  default: `"simple"`

### –discovery-srv, -D ###

*  domain name to query for SRV records describing cluster endpoints
 *  default: none
 *  env variable: ETCDCTL\_DISCOVERY\_SRV

### –peers ###

*  a comma-delimited list of machine addresses in the cluster
 *  default: `"http://127.0.0.1:2379"`
 *  env variable: ETCDCTL\_PEERS

### –endpoint ###

*  a comma-delimited list of machine addresses in the cluster
 *  default: `"http://127.0.0.1:2379"`
 *  env variable: ETCDCTL\_ENDPOINT
 *  Without `--no-sync` flag, this will be overwritten by etcd cluster when it does internal sync.

### –cert-file ###

*  identify HTTPS client using this SSL certificate file
 *  default: none
 *  env variable: ETCDCTL\_CERT\_FILE

### –key-file ###

*  identify HTTPS client using this SSL key file
 *  default: none
 *  env variable: ETCDCTL\_KEY\_FILE

### –ca-file ###

*  verify certificates of HTTPS-enabled servers using this CA bundle
 *  default: none
 *  env variable: ETCDCTL\_CA\_FILE

### –username, -u ###

*  provide username\[:password\] and prompt if password is not supplied
 *  default: none
 *  env variable: ETCDCTL\_USERNAME

### –timeout ###

*  connection timeout per request
 *  default: `"1s"`

### –total-timeout ###

*  timeout for the command execution (except watch)
 *  default: `"5s"`

## Usage ##

### Setting Key Values ###

Set a value on the `/foo/bar` key:

$ etcdctl set /foo/bar "Hello world"
    Hello world

Set a value on the `/foo/bar` key with a value that expires in 60 seconds:

$ etcdctl set /foo/bar "Hello world" --ttl 60
    Hello world

Conditionally set a value on `/foo/bar` if the previous value was “Hello world”:

$ etcdctl set /foo/bar "Goodbye world" --swap-with-value "Hello world"
    Goodbye world

Conditionally set a value on `/foo/bar` if the previous etcd index was 12:

$ etcdctl set /foo/bar "Goodbye world" --swap-with-index 12
    Goodbye world

Create a new key `/foo/bar`, only if the key did not previously exist:

$ etcdctl mk /foo/new_bar "Hello world"
    Hello world

Create a new in-order key under dir `/fooDir`:

$ etcdctl mk --in-order /fooDir "Hello world"

Create a new dir `/fooDir`, only if the key did not previously exist:

$ etcdctl mkdir /fooDir

Update an existing key `/foo/bar`, only if the key already existed:

$ etcdctl update /foo/bar "Hola mundo"
    Hola mundo

Create or update a directory called `/mydir`:

$ etcdctl setdir /mydir

### Retrieving a key value ###

Get the current value for a single key in the local etcd node:

$ etcdctl get /foo/bar
    Hello world

Get the value of a key with additional metadata in a parseable format:

$ etcdctl -o extended get /foo/bar
    Key: /foo/bar
    Modified-Index: 72
    TTL: 0
    Etcd-Index: 72
    Raft-Index: 5611
    Raft-Term: 1
    
    Hello World

### Listing a directory ###

Explore the keyspace using the `ls` command

$ etcdctl ls
    /akey
    /adir
    $ etcdctl ls /adir
    /adir/key1
    /adir/key2

Add `--recursive` to recursively list subdirectories encountered.

$ etcdctl ls --recursive
    /akey
    /adir
    /adir/key1
    /adir/key2

Directories can also have a trailing `/` added to output using `-p`.

$ etcdctl ls -p
    /akey
    /adir/

### Deleting a key ###

Delete a key:

$ etcdctl rm /foo/bar

Delete an empty directory or a key-value pair

$ etcdctl rmdir /path/to/dir

$ etcdctl rm /path/to/dir --dir

Recursively delete a key and all child keys:

$ etcdctl rm /path/to/dir --recursive

Conditionally delete `/foo/bar` if the previous value was “Hello world”:

$ etcdctl rm /foo/bar --with-value "Hello world"

Conditionally delete `/foo/bar` if the previous etcd index was 12:

$ etcdctl rm /foo/bar --with-index 12

### Watching for changes ###

Watch for only the next change on a key:

$ etcdctl watch /foo/bar
    Hello world

Continuously watch a key:

$ etcdctl watch /foo/bar --forever
    Hello world
    .... client hangs forever until ctrl+C printing values as key change

Continuously watch a key, starting with a given etcd index:

$ etcdctl watch /foo/bar --forever --index 12
    Hello world
    .... client hangs forever until ctrl+C printing values as key change

Continuously watch a key and exec a program:

$ etcdctl exec-watch /foo/bar -- sh -c "env | grep ETCD"
    ETCD_WATCH_ACTION=set
    ETCD_WATCH_VALUE=My configuration stuff
    ETCD_WATCH_MODIFIED_INDEX=1999
    ETCD_WATCH_KEY=/foo/bar
    ETCD_WATCH_ACTION=set
    ETCD_WATCH_VALUE=My new configuration stuff
    ETCD_WATCH_MODIFIED_INDEX=2000
    ETCD_WATCH_KEY=/foo/bar

Continuously and recursively watch a key and exec a program:

$ etcdctl exec-watch --recursive /foo -- sh -c "env | grep ETCD"
    ETCD_WATCH_ACTION=set
    ETCD_WATCH_VALUE=My configuration stuff
    ETCD_WATCH_MODIFIED_INDEX=1999
    ETCD_WATCH_KEY=/foo/bar
    ETCD_WATCH_ACTION=set
    ETCD_WATCH_VALUE=My new configuration stuff
    ETCD_WATCH_MODIFIED_INDEX=2000
    ETCD_WATCH_KEY=/foo/barbar

## Return Codes ##

The following exit codes can be returned from etcdctl:

0    Success
    1    Malformed etcdctl arguments
    2    Failed to connect to host
    3    Failed to auth (client cert rejected, ca validation failure, etc)
    4    400 error from etcd
    5    500 error from etcd

## Endpoint ##

If the etcd cluster isn’t available on `http://127.0.0.1:2379`, specify a `--endpoint` flag or `ETCDCTL_ENDPOINT` environment variable. One endpoint or a comma-separated list of endpoints can be listed. This option is ignored if the `--discovery-srv` option is provided.

ETCDCTL_ENDPOINT="http://10.0.28.1:4002" etcdctl set my-key to-a-value
    ETCDCTL_ENDPOINT="http://10.0.28.1:4002,http://10.0.28.2:4002,http://10.0.28.3:4002" etcdctl set my-key to-a-value
    etcdctl --endpoint http://10.0.28.1:4002 my-key to-a-value
    etcdctl --endpoint http://10.0.28.1:4002,http://10.0.28.2:4002,http://10.0.28.3:4002 etcdctl set my-key to-a-value

## Username and Password ##

If the etcd cluster is protected by authentication, specify username and password using the `--username` or `ETCDCTL_USERNAME` environment variable. When `--username` flag or `ETCDCTL_USERNAME` environment variable doesn’t contain password, etcdctl will prompt password in interactive mode.

ETCDCTL_USERNAME="root:password" etcdctl set my-key to-a-value

## DNS Discovery ##

To discover the etcd cluster through domain SRV records, specify a `--discovery-srv` flag or `ETCDCTL_DISCOVERY_SRV` environment variable. This option takes precedence over the `--endpoint` flag.

ETCDCTL_DISCOVERY_SRV="some-domain" etcdctl set my-key to-a-value
    etcdctl --discovery-srv some-domain set my-key to-a-value

## Project Details ##

### Versioning ###

etcdctl uses [semantic versioning][].  
Releases will follow lockstep with the etcd release cycle.

### License ###

etcdctl is under the Apache 2.0 license. See the LICENSE file for details.

[etcd]: https://github.com/coreos/etcd
[Github]: https://github.com/coreos/etcd/releases/
[semantic versioning]: http://semver.org/