how to rsync from a docker container to my host computer

Question

My current development environment allows for automatic code reload whenever changing a file (i.e nodemon / webpack). However I am setting up a kubernetes (minikube) environment so that I can quickly open 3-4 related services at once.

Everything is working fine, but it is not currently doing the automatic code reload. I tried mounting the volume but there is some conflict with the way docker and virtualbox handles files such that the conflict leads to file changes from the host not reflected in docker container. (That's not the first link I have that appears related to this problem, it's just the first I found while googling it on another day)...

Anyways, long story short, ppl have trouble getting live reload done in development. I've found the problem literred throughout the interweb with very few solutions. The best solution I would say I found so far is This person used tar from the host to sync folders.

However I would like a solution from the container. The reason is that I want to run the script from the container so that the developer doesn't have to run some script on his host computer every time he starts developing in a particular repo.

In order to do this however I need to run rsync from the container to the host machine. And I'm having a surprising lot of trouble figuring out how to write the syntax for that.

Let's pretend my app exists in my container and host respectively as:

/workspace/app # location in container
/Users/terence/workspace/app  # location in host computer

How do I rsync from the container to the host? I've tried using the 172.17.0.17 and 127.0.0.1 to no avail. Not entirely sure if there is a way to do it?

examples I tried:

rsync -av 172.17.0.17:Users/terence/workspace/app /workspace/app
rsync -av 127.0.0.1:Users/terence/workspace/app /workspace/app

Answer 1

If you're running the rsync from the host (not inside the container), you could use docker cp instead:

e.g., docker cp containerName:/workspace/app Users/terence/workspace/app

Could you clarify:
1. are you running the rsync from the host or from inside the container?
If it's from inside the container it'll depend a lot on the --network the container is attached to (i.e., bridged or host) and also the mounted volumes (i.e., when you started up the container did you use -v flag?)

Update: For rsync to work from within the container you need to expose the host's dir to the container.

As you think of a solution, keep this in mind: host dir as a data volume

Note: The host directory is, by its nature, host-dependent. For this reason, you can’t mount a host directory from Dockerfile, the VOLUME instruction does not support passing a host-dir, because built images should be portable. A host directory wouldn’t be available on all potential hosts.