Installation and command etcd learning

ETCD learning

Download etcd

#下载
wget https://github.com/etcd-io/etcd/releases/download/v3.3.18/etcd-v3.3.18-linux-amd64.tar.gz
#解压
tar zxvf etcd-v3.3.18-linux-amd64.tar.gz
cd etcd-v3.3.18-linux-amd64.tar.gz
#复制到用户目录
cp etcd etcdctl /usr/local/bin
#赋予执行权限
chmod +x etcd
chmod +x etcdctl

Start etcd

I am as an exercise, will etcd exposed to the public network can be directly accessed via ip, generally not recommended

./etcd --listen-client-urls 'http://0.0.0.0:2379' --advertise-client-urls 'http://0.0.0.0:2379'
# 后台启动 
#nohup etcd --listen-client-urls 'http://0.0.0.0:2379' --advertise-client-urls 'http://0.0.0.0:2379' &

V3 set environment variables (default V2)

export ETCDCTL_API=3
#或者永久设置 vim /etc/profile 在最后添加export ETCDCTL_API=3  然后source /etc/profile

Operation etcd ( reference documentation )

Key-value command

PUT [options] <key> <value>

PUT provided kv value pairs, k, if exists, is covered

options Options

• lease - lease ID (16 hex lease ID) associated with the key
• prev-kv - a key former before returning modified
• ignore-value - the current value is updated using its key
• ignore-lease - use their current lease renewal key

Export

OK

Examples

# 设置
etcdctl put foo bar
# ok

#读取
etcdctl get foo
# foo
# bar

# 设置新kv并读取前一次的kv
etcdctl put foo bar1 --prev-kv
# OK
# foo
# bar

# 读取
etcdctl get foo
# foo
# bar1

# 给key添加租约(需要提前申请租约)
etcdctl put foo bar --lease=1234abcd
# 报错 etcdserver: requested lease not found。需要先申请一个租约

# 申请一个500秒的租约
etcdctl lease grant 500

# 给key添加租约
#lease 694d6ed6e8fed50f granted with TTL(500s)
etcdctl put foo bar --lease=694d6ed6e8fed50f
# OK

# 使用其当前租约更新key(为了使用现有租约)
etcdctl put foo bar4 --ignore-lease
# ok
etcdctl get foo
# foo
# bar4

# 使用当前值更新kv(为了解除租约,保持值不变)
etcdctl put foo --ignore-value
# OK

Remark

If you do not It is given as a command line parameter, the command attempts to read input values from the standard.
If the value is the value includes "-", will be parsed as a flag, this time need to input "-" Resolution

etcdctl put foo -bar4
# Error: unknown shorthand flag: 'b' in -bar4

etcdctl put foo -- -bar4
etcdctl put -- foo -bar5
# OK

May have multiple lines or spaces, it must be wrapped in double quotes, as follows:

etcdctl put foo "bar 1 2 3"
# ok

etcdctl get foo
# foo
# bar 1 2 3

GET [options] <key> [range_end]

If range_end specified, the GET would get the key or key range [key, range_end) left and right to open and close

• hex - hexadecimal coded output kv

• limit - limit the maximum number of result sets

• prefix - get the same prefix key

• order - ascending or descending order to sort the results

• sort-by - according to creation time, Key, modification time, values, goals version sort

• rev - specified version

• print-value-only - only the printing value when used with write-out = simple

• consistency - linear identity or sequence identity

• from-key - look back from the specified Key (comparison of the bytes)

• keys-only - read only key

Output

<key>

<value>

<next_key>

<next_value>

...

Examples

First, set some Key

etcdctl put foo bar
# OK
etcdctl put foo1 bar1
# OK
etcdctl put foo2 bar2
# OK
etcdctl put foo3 bar3
# OK

Reading the key value foo

etcdctl get foo
# foo
# bar

Foo read key value, and performs 16-ary encoding

etcdctl get foo --hex
# \x66\x6f\x6f
# \x62\x61\x72

Reading the key value prefix foo

etcdctl get foo --prefix
# foo
# bar
# foo1
# bar1
# foo2
# foo2
# foo3
# bar3

Reading the key value foo prefix and reverse (the default is the ASCEND)

etcdctl get foo --prefix --order="DESCEND"
# foo3
# bar3
# foo2
# bar2
# foo1
# bar1
# foo
# bar

Read the value of all the key

etcdctl get --from-key ''
# foo
# bar
# foo1
# bar1
# foo2
# foo2
# foo3
# bar3

Reads the values ​​of all key according creation time

etcdctl get foo --from-key '' --sort-by=CREATE
# foo
# bar
# foo1
# bar1
# foo2
# foo2
# foo3
# bar3

Reads the specified version of kv

 etcdctl get foo --rev=0
# foo
# bar

Read only the specified version of the v

etcdctl get foo --print-value-only
# foo

Read only the specified version of k

etcdctl get foo --keys-only
# foo
# 

Reading the key value is greater than the byte ordering of all key equal foo1

etcdctl get --from-key foo1
# foo1
# bar1
# foo2
# bar2
# foo3
# bar3

Reading the key value equals the byte ordering foo1 and less than all of the key foo3

etcdctl get foo1 foo3
# foo1
# bar1
# foo2
# bar2    

Before reading the key value equals foo1 byte ordering all the key 2

etcdctl get --from-key foo1 --limit 2
# foo1
# bar1
# foo2
# bar2

Remark

If any key or value contains unprintable characters or control characters, since the wrap results in a simple format and output may not be clear. To solve this problem, set the --hexhexadecimal encoding of all strings.

DEL [options] <key> [range_end]

If range_end specified, then delete the specified key or key range [key, range_end) left and right to open and close

Options

• prefix - delete the specified prefix key

• prev-kv - kv after deleting the return value

• from-key - backward from the specified Key Delete (comparison of the bytes)

Delete the specified key

etcdctl put foo bar
# OK
etcdctl del foo
# 1
etcdctl get foo

Delete the specified key and returns the value of kv

etcdctl del foo1 --prev-kv
# 1
# foo1
# bar1

Began to be removed from the specified key

etcdctl del --from-key foo
# 2

Remove to foo prefix key

etcdctl del foo --prefix
# 2

TNX [options] (affairs)

TXN etcd read requests from the plurality of standard input and send them as a single atomic transaction applications.

Optional

• hex - hex encoded string output

• interactive - based on interactive prompts for transaction program

Input Format

<Txn> ::= <CMP>* "\n" <THEN> "\n" <ELSE> "\n"
<CMP> ::= (<CMPCREATE>|<CMPMOD>|<CMPVAL>|<CMPVER>|<CMPLEASE>) "\n"
<CMPOP> ::= "<" | "=" | ">"
<CMPCREATE> := ("c"|"create")"("<KEY>")" <CMPOP> <REVISION>
<CMPMOD> ::= ("m"|"mod")"("<KEY>")" <CMPOP> <REVISION>
<CMPVAL> ::= ("val"|"value")"("<KEY>")" <CMPOP> <VALUE>
<CMPVER> ::= ("ver"|"version")"("<KEY>")" <CMPOP> <VERSION>
<CMPLEASE> ::= "lease("<KEY>")" <CMPOP> <LEASE>
<THEN> ::= <OP>*
<ELSE> ::= <OP>*
<OP> ::= ((see put, get, del etcdctl command syntax)) "\n"
<KEY> ::= (%q formatted string)
<VALUE> ::= (%q formatted string)
<REVISION> ::= "\""[0-9]+"\""
<VERSION> ::= "\""[0-9]+"\""
<LEASE> ::= "\""[0-9]+\""

Export

SUCCESSIf etcd successfully processed transaction,
FAILUREthe transaction fails

Examples

Interactive mode if it is determined necessary to press twice enter, the next step

etcdctl put key1 1
etcdctl txn -i
# compares:
mod("key1") > "0"

# success requests (get, put, delete):
put key1 "overwrote-key1"

# failure requests (get, put, delete):
put key1 "created-key1"
put key2 "some extra key"

# SUCCESS

# OK
etcdctl get key --prefix

key1
overwrote-key1
key2
some extra key
# OK

Non-interactive mode

./etcdctl txn <<<'mod("key1") > "0"

put key1 "overwrote-key1"

put key1 "created-key1"
put key2 "some extra key"

'

# FAILURE

# OK

# OK

Remark

When using multi-line TXN command value, line breaks must be expressed is n. Newline character will lead to resolution failure.

COMPACTION [options] <revision> (压缩)

COMPACTION to discard all etcd event history before the scheduled revision. Since etcd multi-version concurrency control model, so it will leave all critical updates event history. When you no longer need to revise the history of the event, all the replaced key can be compressed to reclaim storage space etcd back-end database.

physical - compression to wait to physically remove all old revisions to true

Export

Print compressed version

Examples

etcdctl compaction 1
# compacted revision 1

WATCH [options] [key or prefix] [range_end] [--] [exec-command arg1 arg2 ...] (监听)

Optional

• hex - Hex Trace

• interactive - open interactive session monitor

• prefix - monitor contains prefix key

• prev-kv - kv kv before getting a change

• rev - listening version

Input Format

Interactive mode only accept input.

watch [options] <key or prefix>\n

Export

<event>

[

<old_key>

<old_value>

]

<key>

<value>

...

Examples

Non-interactive mode

Enter etcdctl watch foo command to start listening, listening key when there is a change, print out the event key value

# bash1
etcdctl watch foo

# bash2
etcdctl put foo bar
# ok

# bash1
# PUT
# foo
# bar

LEASE <subcommand> (lease)

LEASE provides lease management set of commands

LEASE GRANT <ttl>

LEASE GRANT server selected time to live (in seconds) to create a new TTL value is greater than or equal to the lease request.

Export

Prints a message with the granted lease ID.

Example

etcdctl lease grant 60
# lease 694d6ed6e8fed554 granted with TTL(60s)

LEASE REVOKE <leaseID>

Rental withdrawal would destroy a given lease, and remove all additional key.

Output

Print the lease is revoked news

Examples

etcdctl lease revoke 694d6ed6e8fed558
# lease 694d6ed6e8fed558 revoked

LEASE TIMETOLIVE <leaseID> [options]

LEASE TIMETOLIVE retrieves a lease information of a given lease ID.

Options

• keys - keys get in on this lease

Export

Print lease information

Examples

# 申请一个租约
etcdctl lease grant 500
# lease 694d6ed6e8fed55b granted with TTL(500s)

# 将租约附加到kv上
etcdctl put foo1 bar --lease=694d6ed6e8fed55b
# OK

# 将租约附加到kv上
etcdctl put foo2 bar --lease=694d6ed6e8fed55b
# OK

# 查看租约的信息
etcdctl lease timetolive 694d6ed6e8fed55b
# lease 694d6ed6e8fed55b granted with TTL(500s), remaining(386s)

# 查看租约的信息和签约的keys
etcdctl lease timetolive 2d8257079fa1bc0c --keys
# lease 694d6ed6e8fed55b granted with TTL(500s), remaining(352s), attached keys([foo1 foo2])

# 查看租约的信息,以json输出
etcdctl lease timetolive 2d8257079fa1bc0c --write-out=json
# {"cluster_id":14841639068965178418,"member_id":10276657743932975437,"revision":31,"raft_term":2,"id":7587842816500225371,"ttl":321,"granted-ttl":500,"keys":null}

# 查看租约的信息和签约的keys,以json输出
etcdctl lease timetolive 2d8257079fa1bc0c --write-out=json --keys
# {"cluster_id":14841639068965178418,"member_id":10276657743932975437,"revision":31,"raft_term":2,"id":7587842816500225371,"ttl":289,"granted-ttl":500,"keys":["Zm9vMQ==","Zm9vMg=="]}

# 租约过期
etcdctl lease timetolive 694d6ed6e8fed55b
# lease 694d6ed6e8fed55b already expired

LEASE LIST

LEASE LIST lists all valid lease

Export

Valid lease list

Examples

etcdctl lease grant 500
# lease 694d6ed6e8fed560 granted with TTL(500s)

etcdctl lease list
# found 1 leases
# 694d6ed6e8fed560

LEASE KEEP-ALIVE <leaseID>

LEASE KEEP-ALIVE refreshed periodically so that the lease does not expire

Output

Print remains active for each sent a message, or printing a message indicating that the lease has expired.

Example

# 起一个10秒生存期的租约
etcdctl lease grant 10
# lease 694d6ed6e8fed562 keepalived with TTL(10)
# lease 694d6ed6e8fed562 keepalived with TTL(10)
# lease 694d6ed6e8fed562 keepalived with TTL(10)
# lease 694d6ed6e8fed562 keepalived with TTL(10)
# lease 694d6ed6e8fed562 keepalived with TTL(10)
...