docker differences as of November 2022

[edsantiago]

Gotta get my issues filed before we start enforcing the "podman info output" requirement!

This is a followup to #14917 and #16430, the reason being that it's just too hard to track a page with lots of edits: after a certain point the blue checkmarks visually overwhelm the non-checked boxes. Let's just start clean every once in a while. This is the list from hack/xref-docker-options as of 2022-11-07, incorporating the edits made in #16430 up through 2022-11-17.

• docker --tls
• docker --tlscacert
• docker --tlscert
• docker --tlskey
• docker --tlsverify
• docker builder
• docker config
• docker container cp --follow-link
• docker container cp -L
• docker container create --domainname add support for podman create/run --domainname #15200
• docker container create --link-local-ip
• docker container create --volume-driver
• docker container run --domainname add support for podman create/run --domainname #15200
• docker container run --link-local-ip
• docker container run --volume-driver
• docker container update --pids-limit
• docker container update --restart
• docker cp --follow-link
• docker cp -L
• docker create --domainname add support for podman create/run --domainname #15200
• docker create --link-local-ip
• docker create --volume-driver
• docker image import --platform
• docker image push --all-tags
• docker image push -a
• docker import --platform
• docker network connect --driver-opt
• docker network connect --link-local-ip
• docker network create --attachable
• docker network create --aux-address
• docker network create --config-from
• docker network create --config-only
• docker network create --ingress
• docker network create --ipam-opt
• docker network create --scope
• docker network inspect --verbose
• docker network inspect -v
• docker push --all-tags
• docker push -a
• docker run --domainname add support for podman create/run --domainname #15200
• docker run --link-local-ip
• docker run --volume-driver
• docker secret create --template-driver
• docker trust Add hidden trust command to alias existing trust commands #16463
• docker update --pids-limit
• docker update --restart
• docker version --kubeconfig

[jakecorrenti]

I'll take on docker container update --pids-limit

[rhatdan]

You got it.

[jakecorrenti]

@edsantiago I forgot to update a commit message and accidentally closed this. I'm sorry

[jakecorrenti]

I'll take docker push -a

[csschwe]

the env option is not currently supported for podman build --secret

docker build --secret id=mysecret,env=MYSECRET

[rhatdan]

@csschwe Please open a new issue on that. This is just a collection of missing options, if an option exists but does not work correctly then open a new issue.

[kwilczynski]

I am unsure if this is the right place or whether I should open a dedicated issue. However, could you also consider adding limits (especially file descriptor limits/fileno) to get the parity between Docker and Podman?

Why? There is a difference between hard/soft fileno for RUN vs CMD (and ENTRYPOINT) in Podman, which is not the case for Docker that seems to be setting 1048576 across the board nowadays, for better or worse, and this seems to trip a lot of users, especially whom are heavily invested in the Red Hat ecosystem (e..g, Podman, Buildah, OpenShift, etc.).

@rhatdan, let me know if this is something you would even consider, and if so, then if you will have some time to work on this or if you would be fine with me sending a Pull Request as a start.

Thank you!

[rhatdan]

Please open a separate issue on this.

[rhatdan]

@kwilczynski BTW, the limits and fileno may not work for rootless users, since podman can not modify limits set on the user.

[jakecorrenti]

I would like to give docker cp --follow-link a shot

[rhatdan]

You got it.

[danishprakash]

@jakecorrenti jfyi, that's already being worked upon and discussed here.

[jakecorrenti]

@danishprakash thanks for pointing that out. Since you're working on it already I'll choose something else to work on

[kwilczynski]

@rhatdan, I have another potential candidate on the above list.

Would you consider adding an item to ensure that when podman build --label or LABEL (in a Dockerfile) is used, it has the same behaviour as Docker, which is to add an empty layer to indicate a change?

We recently had a problem with labels and Quay, and it took us a bit to realise that Buildah has different behaviour. That said, I am unsure if this (as in the compatibility issue) belongs here or to Buildah?

[rhatdan]

Please open an issue on this on Buildah.

[edsantiago]

Closing. Should there be any docker differences worth noting, we will rely on users to file issues.