nic-chen / lua-resty-etcd

Nonblocking Lua etcd driver library for OpenResty

Name

resty-etcd Nonblocking Lua etcd driver library for OpenResty, this module supports etcd API v2.

Table of Contents

• Install
• Methods
  • new
  • get
  • set
  • setnx
  • setx
  • delete
  • wait
  • readdir
  • mkdir
  • rmdir
  • waitdir
  • push
  • version
  • stats_leader
  • stats_self
  • stats_store

Install

Dependencies

• lua-resty-http: https://github.com/ledgetech/lua-resty-http
• lua-typeof: https://github.com/iresty/lua-typeof

install by luarocks

luarocks install lua-resty-etcd

install by source

$ luarocks install lua-resty-http lua-typeof
$ git clone https://github.com/iresty/lua-resty-etcd.git
$ cd lua-resty-etcd
$ sudo make install

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Method

new

syntax: cli, err = etcd.new([option:table])

• option:table
  • host: string - default http://127.0.0.1:2379
  • ttl: int - default -1 default ttl for key operation. set -1 to disable ttl.
  • prefix: string append this prefix path string to key operation url '/v2/keys'.
  • timeout: int request timeout seconds.

The client methods returns either a HTTP Response Entity or an error string.

HTTP Response Entity contains the following fields except 408 timeout status;

• status: number - HTTP status code.
• header: table - response header if status is not 408 timeout status.
• body: string or table - response body if status is not 408 timeout status.

Note: a client method will decode a response body as a JSON string if a Content-Type response header value is a application/json.

local cli, err = require('resty.etcd').new()

Please refer the etcd API documentaion at - https://github.com/coreos/etcd for more details of a response entity.

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get

syntax: res, err = cli:get(key:string)

Gets the value for key.

local res, err = cli:get('/path/to/key')

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set

syntax: res, err = cli:set(key:string, val:JSON value [, ttl:int])

Set a key-value pair.

local res, err = cli:set('/path/to/key', 'val', 10)

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setnx

syntax: res, err = cli:setnx(key:string, val:JSON value [, ttl:int])

Set a key-value pair if that key does not exist.

local res, err = cli:setnx('/path/to/key', 'val', 10)

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setx

syntax: res, err = cli:setx(key:string, val:JSON value [, ttl:int [, modified_index:uint] ])

• modified_index: uint - this argument to use to the prev_index query of atomic operation.

Set a key-value pair when that key is exists.

local res, err = cli:setx('/path/to/key', 'val', 10)

local res, err = cli:get('/path/to/key')

-- this operation will be failed if the `modified_index` of specified key
-- has already been updated by another client.
res, err = cli:setx('/path/to/key', 'val', 10, res.body.node.modifiedIndex)

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delete

syntax: res, err = cli:delete(key:string [, val:JSON value [, modified_index:uint] ])

• val: JSON value - this argument to use to the prevValue query of atomic operation.
• modified_index: uint - this argument to use to the prev_index query of atomic operation.

Deletes a key-value pair.

local res, err = cli:delete('/path/to/key')

local res, err = cli:get('/path/to/key')

-- delete key-value pair if both of `value` and `modified_index` has matched
-- to the passed arguments
res, err = cli:delete('/path/to/key', res.body.node.value,
                      res.body.node.modifiedIndex)

-- delete key-value pair if `value` has matched to the passed value
res, err = cli:delete('/path/to/key', res.body.node.value)

-- delete key-value pair if `modified_index` has matched to the passed
-- modifiedIndex
res, err = cli:delete('/path/to/key', nil, res.body.node.modifiedIndex)

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wait

syntax: res, err = cli:wait(key:string [, modified_index:uint [, timeout:uint] ])

• modified_index: uint - this argument to use to the prev_index query of atomic operation.
• timeout: uint - request timeout seconds. set 0 to disable timeout.

Wait the update of key.

local res, err = cli:wait('/path/to/key')

local res, err = cli:get('/path/to/key')

-- Wait forever the update of key until that modifiedIndex of key has changed
-- to modifiedIndex + 1
res, err = cli:wait('/path/to/key', res.body.node.modifiedIndex + 1, 0)

-- Wait for 10 seconds the update of key until that modifiedIndex of key has
-- changed to modifiedIndex + 2
res, err = cli:wait('/path/to/key', res.body.node.modifiedIndex + 2, 10)

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readdir

syntax: res, err = cli:readdir(key:string [, recursive:boolean])

• recursive: boolean - get all the contents under a directory.

Read the directory.

local res, err = cli:readdir('/path/to/dir')

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mkdir

syntax: res, err = cli:mkdir(key:string [, ttl:int])

Creates a directory.

local res, err = cli:mkdir('/path/to/dir', 10)

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mkdirnx

syntax: res, err = cli:mkdirnx(key:string [, ttl:int])

Creates a directory if that directory does not exist.

local res, err = cli:mkdirnx('/path/to/dir', 10)

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rmdir

syntax: res, err = cli:rmdir(key:string [, recursive:boolean])

• recursive: boolean - remove all the contents under a directory.

Remove the directory

local res, err = cli:rmdir('/path/to/dir')

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waitdir

syntax: res, err = cli:waitdir(key:string [, modified_index:uint [, timeout:uint] ])

• modified_index: uint - this argument to use to the prev_index query of atomic operation.
• timeout: uint - request timeout seconds. set 0 to disable timeout.

local res, err = cli:waitdir('/path/to/dir')

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push

syntax: res, err = cli:push(key:string, val:JSON value [, ttl:int])

Pushs a value into the specified directory.

local res, err = cli:mkdir('/path/to/dir')
res, err = cli:push('/path/to/dir', 'val', 10)

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version

syntax: res, err = cli:version()

Gets the etcd version info.

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stats_leader

syntax: res, err = cli:stats_leader()

Gets the leader statistics info.

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stats_self

syntax: res, err = cli:stats_self()

Gets the self statistics info.

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stats_store

syntax: res, err = cli:stats_store()

Gets the store statistics info.

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