When to pull from Docker repo and when from Git repo and then build?

Question

Suppose I have a machine. It can be a single production server, one of production nodes in a cluster, some kind of staging server, a server or a cluster for testing or a developer workstation. Or something different.

Now I want to deliver app to the machine and run it. I can git pull && docker build. Or I can just docker pull. Or I can git pull to another machine and then scp code instead. Or I can scp docker image tar and then docker load instead of docker pull.

Sure, Git and Docker are completely different and often used both at the same time. However both have repositories and both can be used to store and deliver code. Even the commands themselves are called the same: push and pull. Docker even has image tags which resemble commits to some limited extend. Because tags also help keep several versions of the app.

There is even a tool for delivery of apps in Production completely based on Git. It's Capistrano. Capistrano git pulls the code to anther directory and then redirects a symlink to it in order to deploy.

The question is which reasons to consider when deciding whether to git pull or docker pull the code to deliver it to a machine?

Answer 1

like the other answers say, git is for version control, e.g. for textfiles.

You build a docker container from a "dockerfile" (which is a textfile). This "dockerfile" is placed in a directory with many other files and folders.

So if you put this directory, where the dockerfile is located in, into a git repository, then everyone who has access to it, can build the same docker container, with the same configurations and everything.

is that what you mean?

So, the docker container is a "building" and the DOCKER-repository is a market where you can download already built buildings (images), from that you can run a virtualmachine/container.
And the files in the GIT-repository (this is like a big archive for e.g. documents) are the "construction plans". You "share" the different version of the "construction plans" via git, so everyone can build every version of the building.

Example Workflow:

In your development environment (your local computer):

1. git pull - pull the "construction - instructions" from git repository (e.g. dockerfile)
2. docker build - build the docker image from that dockerfile-instructions
3. docker push myDockerRepo/myDockerImage:latest - push the newly built docker image into the DOCKER repository (NOT the git-repository)

In your production environment:

1. docker pull myDockerRepo/myDockerImage:latest - pull the latest docker image from the DOCKER-repository
2. docker run - run a new containerized instance (basically a VirtualMachine) FROM the docker image

Answer 2

Docker and Git are 2 completely different technologies. Git is a Source Control solution, while in docker you can run apps in docker containers. Think of it a sort of 'new' virtualisation technology. You can use both at the same time hower, no problem.

.... EDIT ...

Docker doesn't keep a copy of your source code. With docker you can build an image based on your source code and put that in a repository. From that image you can run an app in a docker container. So as for workflow basically, you just develop using git, and for deployment you use Docker...