memcached

Memcached is High Performance, Distributed Memory Object Cache

Environment variables

The image recognizes the following environment variables that you can set during initialization be passing -e VAR=VALUE to the Docker run command.

Variable name	Description
MEMCACHED_DEBUG_MODE	Increases verbosity for server and client. Parameter is -vv
MEMCACHED_CACHE_SIZE	Sets the size of RAM to use for item storage (in megabytes)
MEMCACHED_CONNECTIONS	The max simultaneous connections; default is 1024
MEMCACHED_THREADS	Sets number of threads to use to process incoming requests

How to use the container

Pull the image from Docker Hub:

$ sudo docker pull modularitycontainers/memcached

Run the container

docker run -it -p 11211:11211 --name memcached modularitycontainers/memcached

If you would like to debug memcached, use container option -e MEMCACHED_DEBUG_MODE=yes:

docker run -it -p 11211:11211
[-e MEMCACHED_DEBUG_MODE=yes]
--name memcached modularitycontainers/memcached

If you would like to change memcached options, like cache_size, connections or threads, use environment variable -e MEMCACHED_CACHE_SIZE, -e MEMCACHED_CONNECTIONS, -e MEMCACHED_THREADS respectively:

docker run -it -p 11211:11211
[-e MEMCACHED_CACHE_SIZE=<size_in_MB>]
[-e MEMCACHED_CONNECTIONS=<max_simultaneous_connections>]
[-e MEMCACHED_THREADS=<max_concurrent_threads>]
--name memcached modularitycontainers/memcached

A demo

Here is a simple demo how to run memcached

• Copy systemd service which will take care of memcached container:

  $ sudo cp -av memcached-container.service /usr/lib/systemd/system/
  $ sudo systemctl daemon-reload

• We can start memcached now:

  $ sudo systemctl start memcached-container

• You should be able to test memcached by commands (taken from http://www.journaldev.com/16/memcached-telnet-commands-with-example):

  set Test 0 100 10
  JournalDev
  STORED
  get Test
  VALUE Test 0 10
  JournalDev
  END
  replace Test 0 100 4
  Temp
  STORED
  get Test
  VALUE Test 0 4
  Temp
  END
  stats items
  STAT items:1:number 1
  STAT items:1:age 19
  STAT items:1:evicted 0
  STAT items:1:evicted_time 0
  STAT items:1:outofmemory 0
  STAT items:1:tailrepairs 0
  END
  flush_all
  OK
  get Test
  END
  version
  VERSION 1.4.25
  quit

Repository structure

• Dockerfile - build container image with memcached.
• openshift-template.yml - Template for OpenShift to memcached.