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https://github.com/tarantool/memcached

Memcached protocol 'wrapper' for tarantool
https://github.com/tarantool/memcached

memchached tarantool

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Memcached protocol 'wrapper' for tarantool

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# memcached



Memcached protocol 'wrapper' for Tarantool.



## Getting started



### Prerequisites



 * Tarantol 1.6.8+ with header files (tarantool && tarantool-dev packages).

 * Cyrus SASL library (with header files)

 * Python >= 3.7 with next packages (for testing only):

   - PyYAML 5+

   - gevent 21+



### Installation



Clone this repository and then build it using CMake:



``` bash

git clone https://github.com/tarantool/memcached.git

cd memcached

git submodule update --init --recursive

cmake . -DCMAKE_BUILD_TYPE=RelWithDebugInfo -DCMAKE_INSTALL_PREFIX=/usr

make

make install

```



Or use LuaRocks (in this case you'll need `libsmall`, `libsmall-dev`, `tarantool-dev`

packages available from our binary repository at http://tarantool.org/dist/master, and

system package `libsasl2-dev`):



``` bash

luarocks install https://raw.githubusercontent.com/tarantool/memcached/master/rockspecs/memcached-scm-1.rockspec --local

```



### Usage



``` bash

box.cfg{}

local memcached = require('memcached')

local instance = memcached.create('my_instance', '0.0.0.0:11211')

```



Now you're set up and ready to go!



### How to connect



Install Tarantool package from repository ([described here](https://www.tarantool.io/download/)).



Paste the previous example to `/etc/tarantool/instances.enabled/memcached.lua` and start it with

`tarantoolctl start memcached`.



Then try the following example:



``` bash

$ printf "set key 0 60 5\r\nvalue\r\n" | nc localhost 11211

STORED

$ printf "get key\r\n" | nc localhost 11211

VALUE key 0 5

value

END

$ printf "set key2 0 60 6\r\nvalue2\r\n" | nc localhost 11211

STORED

$ printf "get key key2\r\n" | nc localhost 11211

VALUE key 0 5

value

VALUE key2 0 6

value2

END

```



## API



* `local memcached = require('memcached')` - acquire a library handle

* `local slab = memcached.slab.info()` - show information about slab arena and quota.

* `local instance = memcached.create(, , )` - create a new instance, register it and run

  - `name` - a string with instance name

  - `uri`  - a string with uri to bind to, for example: `0.0.0.0:11211` (only TCP is supported now)

  - `opts` - a table with options, the list of possible options is described in the configuration section

* `local instance = instance:cfg()` - (re)configure an existing instance.

  `opts` - a table with options, same as in `create`

* `local instance = instance:start()` - start an instance

* `local instance = instance:stop()` - stop an instance

* `local instance = instance:info()` - return execution statistics



## Configuration



* *readahead* - (default) size of readahead buffer for connection. default is `box->cfg->readahead`

* *expire_enabled* - availability of expiration daemon. default is `true`.

* *expire_items_per_iter* - scan count for expiration (tuples processed in one transaction). default is 200.

* *expire_full_scan_time* - time required for a full index scan (in seconds). default is 3600

* *verbosity* - verbosity of memcached logging. default is 0.

* ~~*flush_enabled* - flush command availability. default is true~~

* *protocol* - the protocol, one of `negotiation`, `binary` or `text`.

  - `negotiation` - detect the protocol automatically at handshake (the default)

  - `binary` - binary memcached protocol

  - `text` - text memcached protocol

* *engine* - the engine to store data in

  - `memory` - store everything in memory. (using `memtx` engine)

  - ~~`disk` - store everything on hdd/ssd (using `vinyl` engine)~~ (not yet supported)

* *space_name* - custom name for a memcached space, default is `__mc_`

* *if_not_exists* - do not throw error if an instance already exists.

* *sasl* - enable or disable SASL support (disabled by default)



## SASL support



Usual rules for memcached are applicable for this plugin:



1. Create user (NOTE: it'll use custom folder):



	 ``` bash

	 echo testpass | saslpasswd2 -p -c testuser -f /tmp/test-tarantool-memcached.sasldb

	 ```



2. Place configuration file `/etc/sasl2/tarantool-memcached.conf`. For example:



	 ```

	 mech_list: plain cram-md5

	 log_level: 7

	 sasldb_path: /tmp/test-tarantool-memcached.sasldb

	 ```

	

	 NOTE: This will disable 'ANONYMOUS' (and other, that aren't listed)

	 authentication plugins.



	 NOTE: This will set logging level to the highest possible



	 NOTE: This will set custom path for database path



3. Run Tarantool with memcached plugin with SASL enabled



	 ```lua

	 local memcached = require('memcached')

	 local instance = memcached.create('my_instance', '0.0.0.0:11211', {

	   sasl = true

	 })

	```



4. Use your favorite binary(!!) memcached client, that supports(!!) SASL:



	 Example using Python's ['python-binary-memcached' library](https://github.com/jaysonsantos/python-binary-memcached)

	 ```

	 import bmemcached

	 client = bmemcached.Client(('127.0.0.1:11211', ), 'testuser', 'testpasswd')

	 client.set('key', 'value')

	 print(client.get('key'))

	 ```



For custom configuration file path, please, use `SASL_CONF_PATH` environment variable.



## What's supported, what's not and other features



**Everything is supported, unless the opposite is stated explicitly**



* Text protocol commands:

  - `set`/`add`/`cas`/`replace`/`append`/`prepend` commands (set section)

  - `get`/`gets` commands (including multiget)

  - `delete` command

  - `incr`/`decr` commands

  - `flush`/`version`/`quit` commands

  - `verbosity` - partially, logging is not very good.

  - `stat` - `reset` is supported and all stats too.

* Binary protocol's commands:

  - `get`/`getk`/`getq`/`getkq` commands (get section)

  - `add`/`addq`/`replace`/`replaceq`/`set`/`setq` commands (set section)

  - `quit`/`quitq`/`flush`/`flushq`/`noop`/`version` commands

  - `gat`/`gatq`/`touch`/`gatk`/`gatkq` commands

  - `append`/`prepend`/`incr`/`decr`

  - `verbosity` - partially, logging is not very good.

  - `stat` - `reset` is supported and all stats too.

  - **SASL** authentication is supported

  - **range** operations are not supported as well.

* Expiration is supported

* Flush is supported

* The protocol is synchronous

* Full support of Tarantool means of consistency (write-ahead logs, snapshots, replication)

* You can access data from Lua

* for now LRU is not supported

* TAP is not supported (for now)

* VBucket is not supported (for now)

* UDP/UNIX sockets are not supported (for now)



## Caution



This rock is in early beta.



## Hacking



We're collecting information for the module developers in the

[HACKING.md](HACKING.md) file.