= Docker =

== Managing docker containers ==

Listing running containers:
{{{
docker ps
}}}

Listing all (including stopped) containers:
{{{
docker ps -a
}}}

Starting, stopping and restarting containers:
{{{
docker (start|stop|restart) <container_name>
}}}

Connecting to a container to e.g. look at log files or modify configuration:
{{{
docker exec -ti <container_name> /bin/bash
}}}

Placing a tail at the container output:
{{{
docker logs -f --tail=100 <container_name>
}}}

Kill all running containers:
{{{
docker kill $(docker ps -q)
}}}

== Managing docker images ==

Listing all docker images:
{{{
docker images
}}}

Cleaning up unused (untagged/dangling) images:
{{{
docker rmi $(docker images -q -f dangling=true)
}}}

== Docker registry ==

<to be filled in>

== Volume containers ==

== Backup and restore ==

=== Backup data in a container ===

Using this method you can create backups outside your container of any data stored in a volume.

General command:
{{{
docker run -ti --rm --volumes-from <container_name> -v <host directory>:<container directory> ubuntu <backup command>
}}}

Examples:
{{{
#Docker registry backup
docker run -ti --rm --volumes-from registry_volume -v /scratch:/backup ubuntu tar-pczvf /backup/registry_data.tgz /etc/registry /srv/registry-data

#Nexus backup
docker run -ti --rm --volumes-from nexus_volume -v /scratch:/backup ubuntu tar -pczvf /backup/nexus_data.tgz /sonatype-work

#Nginx backup
docker run -ti --rm --volumes-from nginx_volume -v /scratch:/backup ubuntu tar -pczvf /backup/nginx_data.tgz /etc/nginx /usr/share/nginx/html /var/log/nginx
}}}


=== Restore data in a container ===

= Dockerized applications =

== CLARIN private docker registry ==

{{{
#pull from docker registry
docker pull registry:latest
#or import from image export
docker load -i docker_registry.tgz

#Create volume container
docker create --name registry_volume -v /etc/registry -v /srv/registry-data tianon/true

#Create application container
docker create --name registry --volumes-from registry_volume -p 127.0.0.1:5000:5000 -e GUNICORN_OPTS=["--preload"] registry:latest

#Optionally restore data into the volume container
docker run -ti --rm --volumes-from registry_volume -v /data/backup/:/backup debian tar -xzf /backup/registry_data.tgz -C /

#Start the registry container
docker start registry

#Check running containers and registry container state
docker ps
docker logs registry
}}}

=== Issues ===

After moving the clarin docker registry from stoor146 to clarinvm and following the above instructions, we ran into the following error when starting the registry container:
{{{
OSError: [Errno 2] No such file or directory: './registry._setup_database.lock'
}}}

As documented in [https://github.com/docker/docker-registry/issues/892 #892], adding the '-e GUNICORN_OPTS=["--preload"]' resolved the issue

=== CLARIN nexus repository ===

{{{
#pull from docker registry
docker pull sonatype/nexus:latest
#or import from image export
docker load -i docker_nexus.tgz

#Create volume container
docker create --name nexus_volume -v /sonatype-work tianon/true

#Create application container
docker create --name nexus --volumes-from nexus_volume -p 127.0.0.1:8081:8081 sonatype/nexus:latest

#Optionally restore data into the volume container
docker run -ti --rm --volumes-from nexus_volume -v /data/backup/:/backup debian tar -xzf /backup/nexus_data.tgz -C /

#Start the registry container
docker start nexus

#Check running containers and registry container state
docker ps
docker logs nexus
}}}

=== NGinx proxy ===

{{{
#pull from docker registry
docker pull clarin:nginx
#or import from image export
docker load -i docker_nginx.tgz

#Create volume container
docker create --name nginx_volume -v /etc/nginx -v /etc/nginx/ssl -v /usr/share/nginx/html -v /var/log/nginx tianon/true

#Create application container
docker create --name nginx --volumes-from nginx_volume -v /root/certstore/wildcard-clarin-eu/bundle.cer:/etc/nginx/ssl/bundle.cer -v /root/certstore/wildcard-clarin-eu/privateKey.key:/etc/nginx/ssl/privateKey.key -p 80:80 -p 443:443 --link nexus:nexus --link registry:registry clarin/nginx

#Optionally restore data into the volume container
docker run -ti --rm --volumes-from nginx_volume -v /data/backup/:/backup debian tar -xzf /backup/nginx_data.tgz -C /

#Start the registry container
docker start nginx

#Check running containers and registry container state
docker ps
docker logs nginx
}}}

== Security Considerations ==

 * [https://www.lvh.io/posts/dont-expose-the-docker-socket-not-even-to-a-container.html Don't expose the Docker socket (not even to a container)]
 * [http://reventlov.com/advisories/using-the-docker-command-to-root-the-host Using the docker command to root the host (totally not a security issue)]

== Relevant Links ==

* Docker volumes
  * https://medium.com/@ramangupta/why-docker-data-containers-are-good-589b3c6c749e
* Docker Application configuration
  * https://dantehranian.wordpress.com/2015/03/25/how-should-i-get-application-configuration-into-my-docker-containers/
* Docker containers and images visually explained:
  * http://merrigrove.blogspot.nl/2015/10/visualizing-docker-containers-and-images.html