Docker: save - produces no output

Question

Fairly new to using Docker..

I pulled an image for Oracle 11g Full. Created a DB and installed an application into the container.

Once configured correctly, I committed the container which resulted in a 15GB image.

Tested a new container of that image, everything works fine, Oracle services etc. startup automatically and then I just attach and run the application...all good.

I need to upload this onto a server, so my intended approach was:

1) Save container
2) Upload tarball to server
3) Load container

However, when I run the following command:

sudo docker save --output ~/etlf_961_meta.tar etlf/informatica9.6.1:latest

it just hangs and produces no output.

The process is active, but no file appears and there is no activity:

T20 chris # ps aux | grep "docker save" root 26179 0.0 0.0 91928 5000 pts/14 S+ 16:36 0:00 sudo docker save --output /home/chris/etlf_961_meta.tar etlf/informatica9.6.1:latest root 26201 0.0 0.0 127404 14664 pts/14 Sl+ 16:36 0:00 docker save --output /home/chris/etlf_961_meta.tar etlf/informatica9.6.1:latest root 26277 0.0 0.0 14232 980 pts/0 S+ 16:36 0:00 grep --color=auto docker save

If I use export and import the process runs fine, a 15GB image is produced and can be imported, however I lose all the ENV and CMD metadata.

Can anyone advise:

1) How to resolve the save command, to actually export the container
or
2) How to restore or attach the ENV/CMD metadata (..the dockerfile?) to a exported/imported image?

Much appreciated

Answer 1

Since you are new to docker I'd like to suggest some things that might make your life easier:

I committed the container which resulted in a 15GB image.

commit is generally not recommended for standard workflows. It is not really reproducible. I would suggest creating a Dockerfile using FROM <oracle image> and doing the work in the Dockerfile.

If you have large datasets you probably want to manage those in volumes or a host bind mount (aka volume mount).

I need to upload this onto a server,

The recommended way of doing this is using docker push to push to a registry.

it just hangs and produces no output.

It could be that it's just very slow? You can also check the docker daemon log file to see if there are any warnings.

How to restore or attach the ENV/CMD metadata (..the dockerfile?) to a exported/imported image?

I don't think this is possible.

Answer 2

https://github.com/docker/for-mac/issues/2308

Version 17.12.0-ce-mac46 (21698) solved this problem, image saved successfully.