I'm new to docker and I wonder why there is no command to fetch AUTOMATED BUILD-repo's Dockerfile to build image locally from it (can be convenient some times I guess, instead of opening browser, peeking for github reference on repo's page and then using git to clone)
I have created dockerfileview to fetch Dockerfile from Docker Hub.
https://github.com/remore/dockerfileview
The automated build normally has a githubrepo behind it and links to the original repository in the build details section under the Source Repository heading. Which automated build are you looking for the source file for?
If you would like to search for images from the command line you can run docker search TERM to find images (but not their docker files). You can also use docker history to give a rough approximation of the commands that went in the docker file.
e.g.
Related
It seems like there are two ways to add documentation to a docker image:
You can add a readme.md in the root folder (where your docker file is located) and this is meant to be parsed by the dockerhub automated build system.
The second way is by using the manifest
https://docs.docker.com/docker-hub/publish/publish/#prepare-your-image-manifest-materials
But the documentation doesn't really explain well how to annotate the manifest file for an image. Also it looks like the manifest command is considered experimental.
What is the recommended way of documenting a docker image?
Personally i prefer not having to add documentation when the container is being built, i would much rather a file in the source control. However the md file method seems to have minimal support.
Most modern container registries (like Dockerhub, Quay, Harbor) have a webinterface that can render and display documentation in Markdown format. When you do automatic builds on Dockerhub from a Github repo, the git repo's README.md can get automatically synced to the repo on Docker Hub. If you build your images locally (or via a CI runner) and push them to Docker Hub you could also push the README file using the docker-pushrm tool. It also supports other container registries than Dockerhub.
I would like to publish docker images tagged with both semantic versions (like version 1.0) and also build numbers (like build 3). Operationally this might come about in the following way:
docker build -t my-project:1.0-1
# make minor changes to docker file
docker build -t my-project:1.0-2
# make minor changes to docker file
docker build -t my-project:1.0-3
# release new version of project
docker build -t my-project:1.1-1
I would expect some users to pin to particular build numbers
docker pull my-project:1.0-2
While other users would just ask for "the lastest of version 1.0"
docker pull my-project:1.0
Does this work? Is there a better way to accomplish this goal?
Yes, this works. A tag is just a friendly name attached to an image ID. Any given image can have as many tags as you would realistically want.
docker tag myproject my-project:1.0-2
docker tag myproject my-project:1.0
Then, if you docker images and find these tags, you'll see that the IMAGE ID for both tags is the same. Keep in mind you'd want to push both tagged images to your repository.
Looking at a couple of popular Docker Hub repos for inspiration:
ruby, python, postgres
I learnt the basics of github and docker and both work well in my environment. On my server, I have project directories, each with a docker-compose.yml to run the necessary containers. These project directories also have the actual source files for that particular app which are mapped to virtual locations inside the containers upon startup.
My question is now- how to create a pro workflow to encapsulate all of this? Should the whole directory (including the docker-compose files) live on github? Thus each time changes are made I push the code to my remote, SSH to the server, pull the latest files and rebuild the container. This rebuilding of course means pulling the required images from dockerhub each time.
Should the whole directory (including the docker-compose files) live on github?
It is best practice to keep all source code including dockerfiles, configuration ... versioned. Thus you should put all the source code, dockerfile, and dockercompose in a git reporitory. This is very common for projects on github that have a docker image.
Thus each time changes are made I push the code to my remote, SSH to the server, pull the latest files and rebuild the container
Ideally this process should be encapsulated in a CI workflow using a tool like Jenkins. You basically push the code to the git repository,
which triggers a jenkins job that compiles the code, builds the image and pushes the image to a docker registry.
This rebuilding of course means pulling the required images from dockerhub each time.
Docker is smart enough to cache the base images that have been previously pulled. Thus it will only pull the base images once on the first build.
I have set up an automated build from a Github repository for an application in Docker hub, but as part of the build process, I'd like to be able to write the current tag name to a local file.
Does Docker hub provide any environment variable with the name of the tag being built, which I can echo into a local VERSION file?
I'd like to avoid actually installing git inside the container to perform a describe, as well as including the entire (currently dockerignored) .git folder to retrieve this info.
Thank you!
I have been playing around with docker for about a month and now I have a few images.
Recently, I want to share one of them to some other guy,
and I push that image X to my DockerHub, so that he can pull it from my repository.
However, this seems kind of a waste of time.
The total time spent here is the time I do docker push and the time he do docker pull.
If I just sent him the Dockerfile needed to build that image X, then the cost would be
the time I write a Dockerfile, the time to pass a text file, and the time he do docker build,
which is less than previous way since I maintain my Dockerfiles well.
So, that is my question: what are the pros/cons of these two approach?
Why Docker Inc. chose to launch a DockerHub service rather than a DockerfileHub service?
Any suggestions or answers would be appreciated.
Thanks a lot!
Let's assume you build an image from a Dockerfile and push that image to Docker Hub. During the build you download some sources and build a program. But when the build is done the sources become unavailable. Now the Dockerfile can't be used anymore but the image on Docker Hub is still working. That's a pro for Docker Hub.
But it can be a con too. For example if the sourcecode contains a terrible bug like Heartbleed or Shellshock. Then the sources get patched but the image on Docker Hub does not get updated.
In fact, the time you push image and the time you build image depend on your environment.
For example, you may prebuild a image for embedded system, but you won't want to build it on embedded system.
Docker Hub had provided an Automated Builds feature which will fetch Dockerfile from GitHub, and build image. So you can get the Dockerfile of image from GitHub, it's not necessary to have a service for sharing Dockerfile.