Psych gem build error `yaml.h not found` and followup

How To
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1

All of a sudden my build step was failing with the following

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
    current directory: /usr/local/bundle/ruby/3.4.0/gems/psych-5.2.2/ext/psych
/usr/local/bin/ruby extconf.rb
checking for pkg-config for yaml-0.1... not found
checking for yaml.h... no
yaml.h not found
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Psych is a YAML Ruby gem and relies on libyaml and yaml.h not found looks like a missing dependency. If FROM docker.io/library/ruby:$RUBY_VERSION-slim is similar to your Dockerfile, all you need is to add libyaml-dev where ever you’re installing dependencies for a build phase.

What I’d love to know is why this appears to have happened without a change on my end and how I can be informed of another similar change.

2

Hi @agrberg,

It’s not necessarily related to our changes. Some of your dependencies could change too.
What’s your service ID? I will take a closer look.

3

My original post was unclear, I don’t think this is related to Koyeb at all.

I actually managed to track it down. It appears libyaml-dev was removed from the Ruby slim and alpine images two days ago, when this started happening. There’s a lot more information in that GH issue. I kind of got lucky as I was looking for the Rails Dockerfile template and noticed libyaml-dev is now included!

In answer to how can I be informed, it appears that’s a lot of the discussion on the GH issue page. In answer to how could this happen w/o a change on my end, I need to understand if there’s a versioning and locking system w/ base Docker images similar to semver as letting that float to latest is how this was introduced.

4

It looks like this is being reverted for the disruption FWIW

5

Wow, interesting case. To protect yourself from such cases, you would need to build everything from scratch :confused:

Anyway, thank you for updating the topic with such a detailed description!

6

Happy to help out and leave a good trail of breadcrumbs for the next dev :+1:

I am a Docker novice but I believe images can be tagged. The next things to explore are

  • How are tags utilized in Dockerfiles to ensure the base image consistency (i.e. cannot be updated w/o me taking an action or update)
  • How to determine if a base image update is “safe” to deploy. E.g. for updating gems/dependencies, I can run my test suite to get a really good idea. Do I need a local Docker build and run to ensure this?