Binary `x86_64-linux` Gem Fails to Load Shared Library `libresolv.so.2` on Alpine Linux

[olly]

Upgrading to v1.6.0 on Alpine Linux results in a runtime error when loading pg:

LoadError: cannot load such file -- pg_ext (LoadError)

...

Caused by:
LoadError: Error loading shared library libresolv.so.2: No such file or directory (needed by /usr/local/bundle/gems/pg-1.6.0-x86_64-linux/lib/3.3/../../ports/x86_64-linux/lib/libpq-ruby-pg.so.1) - /usr/local/bundle/gems/pg-1.6.0-x86_64-linux/lib/3.3/pg_ext.so (LoadError)

I believe this has been caused by the inclusion the binary gems in the latest release, and presumably these are build against glibc. Under 1.5.9 we were able to build these gems from source on Alpine Linux.

We were able to continue building from source by adding the force_ruby_platform to our Gemfile.

gem 'pg', force_ruby_platform: true

---

I'm not to familiar with how compiled gems work, but I think perhaps the platform specifier could be made more specific; by changing the currently build gem's platform from x86_64-linux to x86_64-linux-gnu.

It appears that while there is a CI action to test Alpine compatibility it installs the gcompat glibc compatibility layer, which I assume is why this wasn't noticed previously.

I suspect that, additionally, a binary gem could be built for the x86_64-linux-musl platform as it appears to compile and work correctly without the gcompat glibc compatibility layer.

[larskanis]

Sorry for breaking your app! pg gem on Alpine it expected to require the gcompat package for the native gem. I wrote this in #551 (comment) , but it didn't find its way into the README so far.

Maybe there will be a x86_64-linux-musl platform gem in the future, but for now these are the two options:

sudo apk add gcompat

or

gem 'pg', force_ruby_platform: true

[olly]

@larskanis absolutely no problems, it was all caught by our test suite.

I understand adding a dependency on gcompat to simplify your testing matrix. Just catching up on your linked comment, you note that it's a requirement for nokogiri, I'm not sure that is the case; and it appears they've shipped musl compatible binaries since v1.18 release (~December 2024).

Perhaps you may consider changing the platform to the more-specific x86_64-linux-gnu? But I understand there are alternative solutions, which both work.

Thanks for all your hard work. ❤️

[stanhu]

Testing out #649.

I do recall seeing mysterious seg faults in other precompiled gems when used with Alpine. I think splitting gnu and musl builds is what most precompiled gems do now (grpc, nokogiri, etc.).