Add missing contrib modules / pl extensions to alpine image #906
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I think this is going to lead to a non-trivial image size increase. See also #384 for a useful previous discussion on this topic. |
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... @yosifkit kindly pointed out that the table in your message covers this 🤦 Looking at the builds themselves, |
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Nope, it'll go up as soon as we decide to make (and merge) a PR over to official-images. See also https://github.com/docker-library/postgres/tree/bafaf65a2356a05810c12a03d4412e1003cd1bb8#see-a-change-merged-here-that-doesnt-show-up-on-docker-hub-yet. |
Ok, cool. I'll watch that closely. Yeah, I went through that (and the FAQ the link points to) already, but the change in that example is about a version update. That creates new tags, so it all kinds of makes sense. I couldn't tell from the FAQ what that means for "non-version-update" changes, though. Would those recreate the latest version tag? I always assumed that, once I reference a "full-version" image (e.g. I probably just missed that part in the FAQ. |
Changes: - docker-library/postgres@bafaf65: Merge pull request docker-library/postgres#906 from wolfgangwalther/alpine/add-missing-contrib - docker-library/postgres@e331a5b: Build alpine images --with-krb5, --with-gssapi and --with-ldap - docker-library/postgres@5d9e5a4: Build plperl, plpython and pltcl in alpine images
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Yeah, any tag is mutable. We rebuild images when either a PR is merged to official-images that changes its build context (Dockerfile, shell scripts, etc) or any of its parent images can cause a rebuild (e.g. our rebuilding of Debian every ~30 days causes all dependent images to rebuild). Even when rebuilding for just a Dockerfile change, If anyone needs immutable references, then they should use the content addressable digest ( |
The readme on dockerhub says:
However, not all extensions in contrib are available. The language extension
plperl,plpythonandpltcl, as well as related contrib modules (e.g.hstore_*,jsonb_*, ...) are missing.Only in very rare cases, when the postgres version matches the one distributed in the current alpine distribution, one can install e.g.
plpythonviaapk add postgresql-plpython3(with a bit of moving files around to their proper location). However, this is not sustainable: It currently works for pg 13.x on alpine 3.14, but not for pg 14.x anymore.Compiling those extensions from source kind of defeats the purpose of deriving from this image in the first place.
Currently, those extensions seem to be left out on purpose:
postgres/Dockerfile-alpine.template
Lines 104 to 110 in a11e908
I investigated the potential increase in image size a little bit. It seems like the biggest chunk results from additional dependencies in perl, python and tcl. However, those can be avoided, if we build the extension, but then remove the dependencies for them. This means the above mentioned extensions will only be usable after installing the dependencies in a derived image again - but that's already a huge step forward.
As an example, using
plpythonwould be as simple as:I looked at image size in 4 cases:
master: current master branch+PLfull: compiled language extension, but kept the dependencies+PL: compiled language extensions, but removed dependencies+PL+auth: same as before, but also compiled--with-krb5,--with-gssapiand--with-ldapThe last one was just because those were commented out, too, and I wondered what it would cost to enable them now.
The data shows that indeed the biggest chunk comes from perl, python and tcl. The increase in image size for the other two cases however is really small.
I suggest to enable both the language extensions as well as
--with-krb5,--with-gssapiand--with-ldap, but leave out the 3 major dependencies to keep image size small. This will make the alpine image much more usable.