--mount=type=cache location

[tmds]

Where do the files get stored when using --mount=type=cache,id=<id>,target=<target>,Z?
And where when leaving out the <id>?

cc @mheon @rhatdan

[flouthoc]

Hi @tmds, It gets stored on your host $TMPDIR/buildah-cache and if $TMPDIR is not set it is /var/tmp/buildah-cache and when id option is selected it becomes $TMPDIR/buildah-cache/<id> or /var/tmp/buildah-cache/<id> depending upon if $TMPDIR was set.

I hope this answers your question.

Ref: https://github.com/containers/buildah/blob/main/pkg/parse/parse.go#L49

[flouthoc]

Ah i meant podman image prune i'll check and open a PR against image prune it if it doesn't already cleans build cache. I also wonder if this fits more in podman build prune .. ? A new command which can remove build containers and build cache but I am not sure if everybody would encourage creating a new command just for this.

Thanks for reporting this.

[flouthoc]

@cgwalters Created a PR #23846

[parkan]

did this behavior change recently? I am running:

RUN --mount=type=cache,id=pip,target=$HOME/.cache/pip pip3 install --upgrade pip wheel setuptools ...

with no TMPDIR set and the only directories with similar names are:

❯ ls -lh /var/tmp/buildah-cache-1000/
Permissions Size User    Date Modified Name
drwxr-xr-x@    - arkadiy  9 Jan 13:47  41cddf472639a12b
drwx------@    - arkadiy  9 Jan 14:57  buildah-cache-lockfiles
drwxr-xr-x@    - arkadiy  9 Jan 14:57  fed5038bf2f427ab

furthermore the cache does not seem to actually be working (subsequent runs re-download the pip packages and all subdirs in the buildah-cache-1000 dir are empty

(my uid is 1000 and podman version is 5.3.1)

[nalind]

Yes, containers/buildah#5778 changed it so that we don't directly use the "id" (or "target", if "id" isn't specified) in constructing the path to the top level of the cache - whichever one we're given is hashed to produce a subdirectory name to avoid shenanigans.

[nalind]

When I tried your example instruction using registry.redhat.io/ubi9/python-312 as a base image, I had to specify the "uid" option to ensure that the cache was writeable by the non-root user the image used as a default, and had to use pip3's "--cache-dir" option to actually use the cache directory, but that could equally be explained by my not being familiar with pip.