Since end of May, thanks to the great efforts of the GitLab project developers, an open source authorization-layer for the docker-registry(v2) is available.
Within this article I´d like to introduce my collegues into the basic steps to work with docker and our new private docker-registry.
The so called docker-registry is like a git-repository for so called docker-images.
Enable the registry for your project
- Sign in to code.webrunners.de
- Go to your project: /namespace/projectname
- Click on Settings: /namespace/projectname/edit
- Under „Features“ enable „Container registry“ and save
- Go back to project and click on the new available „Container Registry„
This is the page where you will see and manage your pushed images.
There is also a nice little help written.
Now your project-namespace is ready to use for pushing and pulling docker images.
Example of usage
On your command line:
- Create a docker image
- Name (tag) it to registry.webrunners.de/namespace/projectname:tag
- Login docker to our registry
- Push the image
- Now, others with project-access are able to pull it
Assuming you already have installed docker for your OS…:
…you should be able to execute the docker client on your command line.
Docker, as it is one big binary that is written in Golang, has different subcommands.
I will list some in a meaningful order:
docker ps # List all currently running processes (docker container) docker images # List all images, which are the base for containers docker run image/name # Start a container from an image
Containers are like linked clones to images. You can think of containers as running state and images as frozen state. They don´t alter the images, but are a new isolated layer upon them to make use of preinstalled software.
You can get images from hub.docker.com, or build them locally e.g. to push later to our private registry.
A simple workflow
- Get an public available image from docker hub
- Run it locally for testing
- Adapt it
- Commit it and save it to a new image
- Rename the image for pushing to our registry
- Deleting locally and rerun/pull to verify all is as expected
docker pull elyase/staticpython
II) For Windows you could try
%CD% instead of
$(pwd). Alternatively you can write the full path to the current directory. On Windows use this notation:
docker run -p 8000:8000 -v $(pwd):/src -w /src --rm -it elyase/staticpython sh -c 'python -m SimpleHTTPServer'
Don´t forget to check
docker subcommand --help
run– Subcommand to start an image
-p– Publish a port to the docker-host
-v– Mount a local directory, or a so called Volume within the container
-w– When starting the container use this as the working directory
--rm– After stoping the container, delete it. See
docker ps -afor exited containers that might be used again, or just eat disk-space.
-it– Short for
-i -t. Start an interactive terminal session
elyase/staticpython– The image to use
sh -c 'python -m SimpleHTTPServer'– All the rest is a command to run. Here we only start a little webserver
If you use docker-machine, get the docker-host-IP with
docker-machine ls. Now you should be able to open a browser to see your current directory files:
Go to: http://docker-host-IP:8000
For me it´s: http://192.168.99.100:8000
Quit the Container with
III) Now we run the container again in detached mode, and run some commands inside. Note that we don’t use a shared Volume this time, as it could not be committed to an image. Also we name the container this time.
docker run -d --name charly -p 8000:8000 -w /src -it elyase/staticpython sh -c 'python -m SimpleHTTPServer' # We wrap the python command, because it didn´t respond to Ctrl-C in my tests docker exec charly sh -c 'echo "We run webs" > index.html' # We have to wrap the command inside the sh command because of the redirection.
Now I can see the page on 192.168.99.100:8000 again.
We could do some work directly inside a shell session:
docker exec -it charly sh /src # echo "Go on spider" >> index.html /src # exit
docker commit -m "Some test" charly registry.webrunners.de/namespace/project:test
You should see now the commit under
And could rename it later with
Now use your GitLab credentials:
docker login registry.webrunners.de
docker push registry.webrunners.de/namespace/project:test
You can manage the image on:
VI) As the container is still running locally and the just created image (commit) still exist, we now delete them.
docker kill charly docker rm charly docker rmi registry.webrunners.de/namespace/project:test docker images docker ps
docker run --rm -it registry.webrunners.de/namespace/project:test Unable to find image 'registry.webrunners.de/namespace/project:test' locally test: Pulling from namespace/project ... ...
Now we put all of this inside a build script. The so called Dockerfile.
Create two files
We run webs Go on spider
FROM elyase/staticpython COPY index.html /src/ WORKDIR /src CMD ["sh", "-c", "python -m SimpleHTTPServer"]
docker build -t registry.webrunners.de/namespace/project . docker tag registry.webrunners.de/namespace/project:latest registry.webrunners.de/namespace/project:spider
docker run -it --rm -p 8000:8000 --name charly registry.webrunners.de/namespace/project:spider
docker push registry.webrunners.de/namespace/project:spider
docker kill charly docker rm charly docker rmi registry.webrunners.de/namespace/project:test docker rmi registry.webrunners.de/namespace/project:spider docker rmi registry.webrunners.de/namespace/project:latest docker ps -a docker images
There are buttons to delete the pushed images.
Docker push will loop to upload and finally give up on big layers.
This should be fixed in a next GitLab release:
- Dockerfile Reference
- Docker run Reference
- Docker compose
- Gitlab CI using registry
- Running ASP.NET 5 applications in Linux Containers with Docker
- Docker und .NET – ein Beispiel