Crowdr

Crowdr is a extremely flexible tool for managing multiple Docker containers.

Why not bash/make?

• pure bash - too much boilerplate code
• make - even more boilerplate code

Why not docker-compose?

• lack of variables
• options support is always behind actual docker version
• up restarts containers in wrong order
• hasslefree replacement for non x86/x86_64 architectures

What is wrong with docker-compose up?

client:
    image: ubuntu
    command: sleep infinity
    links:
        - server

server:
    image: ubuntu
    command: sleep infinity

$ docker-compose up -d
Creating test_server_1...
Creating test_client_1...

First start is ok. Server started before a client.

$ docker-compose up -d
Recreating test_server_1...
Recreating test_client_1...

As you can see, server recreated first. It means that client will loose the connection.

To avoid that we need to use this order:

• stop client
• stop server
• recreate & start server
• recreate & start client

Installation

# curl -s https://raw.githubusercontent.com/polonskiy/crowdr/0.9.1/crowdr > /usr/local/bin/crowdr
# curl -s https://raw.githubusercontent.com/polonskiy/crowdr/0.9.1/completion > /etc/bash_completion.d/crowdr

Crowdr commands

crowdr version - prints current crowdr version

crowdr run - (default) runs all containers

crowdr build - builds all images

crowdr stop - stops all containers

crowdr start - starts all containers

crowdr restart - stops all containers and starts them again

crowdr kill - kills all containers

crowdr rm - removes all stopped containers from current config

crowdr rmi - removes all not otherwise used images contained in current config

crowdr ps - shows running containers from current config

crowdr ip - shows IP addresses of running containers from current config

crowdr shell foo - start bash shell inside foo container

crowdr exec foo ls - run ls inside foo container

echo 111 | crowdr pipe foo tr 1 2 - pipe data to tr 1 2 command inside foo container

crowdr stats - shows stats

Configuration

• crowdr sources .crowdr/config.sh and read stdout
• blank lines are ignored
• lines starting with # are ignored.
• you can override config filename using CROWDR_CFG variable (CROWDR_CFG=~/foo/bar/baz.sh crowdr)
• you can enable debug mode using CROWDR_TRACE variable (CROWDR_TRACE=1 crowdr |& less)
• review planned commands without executing them using CROWDR_DRY variable (CROWDR_DRY=1 crowdr |& less)
• containers run in the order as in config, stop in reversed

Sample .crowdr/config.sh:

#!/bin/bash

HOST="$(tr -d '-' <<< $HOSTNAME)"
PREFIX="foo"

echo "
global project ${USER}_${HOST}_myproject

mysql build docker/mysql
mysql hostname $PREFIX-mysql
mysql volume $PWD/mysql-data:/var/lib/mysql

#comment

apache build docker/apache
apache hostname $PREFIX-apache
apache memory 5g
apache link mysql
apache volume $PWD:/var/www
apache env-file config.env
"

Benefits:

• bash support
• full docker run options support

project option (global)

global project myproject

Global option for name of project. All container names will be silently prefixed with this name and separator char. If it is not set current directory name used.

project_sep option (global)

global project_sep "_"

Separator string used after project name. If it is not set _ is used.

For example for following configuration all containers will be prefixed with myproj-

global project myproj
global project_sep "-"

build option

build - path to a directory containing a Dockerfile

container_name build some/path

image option

image - image name. If image doesn't exists docker will try to download it.

container_name image ubuntu:14.04

command option

command - overrides CMD from Dockerfile/image

container_name command tail -f /dev/null

Run options

Format is following

container_name option value

Full reference

Hooks

Every crowdr command can be extended. Lets say you want to pull in some Dockerfiles from remote repositories before running crowdr build.

$ mkdir .crowdr/hooks
$ echo 'echo pulling repos' > .crowdr/hooks/build.before
$ echo 'git clone http://github.com/someuser/docker.redis' >> .crowdr/hooks/build.before
$ echo 'git clone http://github.com/someuser/docker.proxy' >> .crowdr/hooks/build.before
$ chmod 755 .crowdr/hooks/*
$ crowdr build
pulling repos

Crowdr detects both .before and .after-hooks of each crowdr command.

Not supported (yet)

• partial build/run/stop
• build --no-cache
• --volumes-from
• external links