• Docker image - operating system with preconfigured application (service)
• Docker container - running instance created from docker image
• Data volume - persistent storage of data outside of container. Can be shared between containers.
• Dockerfile - is a recipe which describes the files, environment, and commands that make up an image.
• docker-compose - tool for defining and running multi-container Docker application (e.g. web app + mysql db). Compose preserves all volumes used by your services. When docker-compose up runs, if it finds any containers from previous runs, it copies the volumes from the old container to the new container. This process ensures that any data you’ve created in volumes isn’t lost.

Create new container based on image and execute optional command inside.

docker run -i --rm busybox
docker run -i --rm busybox ps aux
docker run -i --rm debian:jessie-slim
docker run -i --rm nginx bash

• docker run - run new isolated container …
  • -rm to Automatically remove the container when it exits
  • –restart always
  • –name

docker run --rm -ti -v `pwd`:/opt/myservice remote/path

--rm                            Automatically remove the container when it exits
-i, --interactive               Keep STDIN open even if not attached
-t, --tty                       Allocate a pseudo-TTY
-v, --volume=[]                 Bind mount a volume

How to run multiple shell commands in docker at once:

docker run image /bin/bash -c "cd /some/path && some_command"

docker stop sends SIGTERM to PID1 and waits 10 seconds before force kill SIGKILL.

docker stop ----time=30 foo

docker kill ----signal=SIGWINCH apache
docker kill ----signal=SIGQUIT nginx

More on handling signals https://www.ctl.io/developers/blog/post/gracefully-stopping-docker-containers/

docker update --restart=always 5ba1f7f3d67e
# or usign container name
docker update --restart=always portainer

https://blog.ouseful.info/2015/08/10/seven-graphical-interfaces-to-docker/

Usefull:

• https://github.com/kevana/ui-for-docker deprecated by:
• https://github.com/portainer/portainer

  • docker run -d -p 9000:9000 -v /var/run/docker.sock:/var/run/docker.sock --name portainer --restart always portainer/portainer

  • https://portainer.readthedocs.io/en/latest/configuration.html

Working:

• docker-compose-ui
  • https://github.com/francescou/docker-compose-ui

Not working:

• http://panamax.io/
  • CoreOS required, so they provide ready Virtualbox or Vagrant recipe
  • https://github.com/CenturyLinkLabs/panamax-ui/wiki/Installing-Panamax
  • Install command:

    curl http://download.panamax.io/installer/ubuntu.sh | bash

• Generates a nice graph showing the hierarchy of Docker images in your local image cache https://github.com/CenturyLinkLabs/docker-image-graph
  • Doesn't work with current docker version

Other managers

• https://github.com/ClusterHQ/flocker

No universal backup solution. Possible scenarios:

• docker images - use docker save
• running container:
  • pause (but what with not flushed data?)
  • commit container as image (volumes are not included!)
  • backup a image using save
• backup data volumes
  • gracefully stop container to ensure all data are flushed
  • run new container only to execute backup script on other container's volume –volumes-from
• connect remotely to service to get dump (i.e. mysql)
• configure service to make daily backup to bind mounted host directory

To make backup of running container it is need to commit its current state and save as docker image. With option -p container will be paused before saving snapshot.

# docker commit -p portainer portainer1
sha256:c48af304eed09c0ef7f557e6f5e02f10b2637c4c02dd765c186ee29805c31272
 
# docker images
REPOSITORY              TAG                 IMAGE ID            CREATED              SIZE
portainer1              latest              c48af304eed0        About a minute ago   9.16 MB

Now image can be pushed to remote hub or registry. See man docker push Or dumped to file:

docker save -o portainer1.tar portainer1

To load dump file check man docker load

To get data from container outside:

$ sudo docker run --rm --volumes-from dbdata -v $(pwd):/backup busybox tar cvf /backup/backup.tar /dbdata

export exports only container filesystem and has some limitations: it won't export the data volume (VOLUME in Dockerfile or specified by -v)

docker export $CONTAINER_ID > $CONTAINER_ID-backup.tar
docker import - slava/$CONTAINER_ID-backup < $CONTAINER_ID-backup.tar

Create build directory and Dockerfile

Dockerfile

FROM debian:jessie-slim
RUN apt-get -y update && apt-get install -y fortunes
CMD /usr/games/fortune -a | cowsay

docker build -t mydocker .
docker run mydocker

# docker start 7cda5b580e16
Error response from daemon: endpoint with name portainer already exists in network bridge
Error: failed to start containers: 7cda5b580e16

https://github.com/moby/moby/issues/23302

Typically when you see containers in docker network inspect output with a ep- prefix, that means it can be either of 2 cases -

  these are stale endpoints left over in the DB. For those cases, docker network disconnect should help.
  these are remote endpoints seen in other nodes that are part of the overlay network. The only way to clean them up are from that specific host.

Not helping:

docker network prune

docker network disconnect -f bridge portainer

Helps:

/etc/init.d/docker restart