Segfault with Musl-LibC on MRI inside of Alpine Linux.

[envygeeks]

[BUG] Segmentation fault at 0x00000000000000
discourse_1  | ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-linux-musl]
discourse_1  | 
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[cowboyd]

@envygeeks Thanks for submitting this bug. We're currently working on the next version of the ruby racer that should address instability issues such as this. If you could outline the steps you took to generate this error, I'd be eager to include it into the regression suite in order to make sure that it does not happen again.

[envygeeks]

gem install therubyracer -- --use--system-libraries You might want to pre-install libv8 with a source version (as you already know) because alpine has no glibc, then you can install Discourse and it will trigger the bug 100% of the time with rake assets:precompile.

Gonna CC @SamSaffron and @eviltrout ... even though they don't support Alpine Linux as a Docker image (or any Docker image that is not their own) they can provide inside into what their code is doing so I can build a re-production script without the need to install full Discourse to trigger it.

[envygeeks]

As a sidenote @cowboyd I would love to try the new version if it's available.

[cowboyd]

It can be found here #348

It should be noted that large portions of the API remain either omitted or broken. That said, it can do basic javascript evaluation.

Here is the parts of the test suite that are currently passing https://github.com/cowboyd/therubyracer/blob/upgrade-to-v8-4.5/spec/v8/context_spec.rb

[johnae]

Also having trouble on Alpine Linux. I get a load error because of missing symbol:

/srv/service/vendor/bundle/ruby/2.1.0/gems/activesupport-3.2.18/lib/active_support/dependencies.rb:251:in `require': Error relocating /srv/service/vendor/bundle/ruby/2.1.0/extensions/x86_64-linux/2.1.0-static/therubyracer-0.12.1/v8/init.so: __vfprintf_chk: symbol not found - /srv/service/vendor/bundle/ruby/2.1.0/extensions/x86_64-linux/2.1.0-static/therubyracer-0.12.1/v8/init.so (LoadError)
        from /srv/service/vendor/bundle/ruby/2.1.0/gems/activesupport-3.2.18/lib/active_support/dependencies.rb:251:in `block in require'
        from /srv/service/vendor/bundle/ruby/2.1.0/gems/activesupport-3.2.18/lib/active_support/dependencies.rb:236:in `load_dependency'
        from /srv/service/vendor/bundle/ruby/2.1.0/gems/activesupport-3.2.18/lib/active_support/dependencies.rb:251:in `require'
        from /srv/service/vendor/bundle/ruby/2.1.0/gems/therubyracer-0.12.1/lib/v8.rb:4:in `<top (required)>'
        from /usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `require'
        from /usr/local/lib/ruby/gems/2.1.0/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in `block (2 levels) in require'
...

[ignisf]

@johnae, can you check if rubygems installed a binary version of libv8 on your system? (Paste the output of gem list libv8)

@cowboyd, does rubygems even acknowledge the existence of different implementations of libc?

[johnae]

@ignisf possibly it did:

bundle exec gem list libv8

*** LOCAL GEMS ***

libv8 (3.16.14.7 x86_64-linux)

I tried doing this:

bundle config build.therubyracer --use-system-libraries
bundle config build.libv8 --with-system-v8

Didn't seem to have any effect.

[ignisf]

As far as I see, Alpine provides v8 3.26. I am almost certain that they changed v8's API several times between 3.16 and 3.26 :(. therubyracer is most probably incompatible with it. You could try explicitly setting a source version of libv8 in your Gemfile and try again. See https://github.com/cowboyd/libv8#source-and-binary-releases

[ignisf]

(also, remove the use system libraries switch from the bundle config beforehand)

[envygeeks]

You need to use --use-system-libraries and skip the --with-system-v8

[envygeeks]

The whole point of skipping the latter is to get therubyracer to compile it's bundled v8 with musl.

[johnae]

@envygeeks actually I got it compiling and working on Alpine with no switches at all. I just set a source only version in the Gemfile as suggested here.

[envygeeks]

The argument is so you don't have to rely on all that. How about you provide more information instead because the broad statements made provide me with no way to validate this so we can release Alpine images with rubyracer. Such as: Versions, musl version, Alpine version (we use edge here and only edge...) are you sure it actually compiled and works as you think it does? The latter part isn't me trying to say you don't know how it works, it's me saying, it was a week before we could reliably trigger a segfault on Alpine.

[johnae]

Sure. The only thing I know is that in our case it compiles and all specs pass in a relatively large Rails app (using source only versions of libv8 as previously suggested). Whether it will segfault in a week I can't say. Here's some more info:

NAME="Alpine Linux"
ID=alpine
VERSION_ID=3.2.3
PRETTY_NAME="Alpine Linux v3.2"
HOME_URL="http://alpinelinux.org"
BUG_REPORT_URL="http://bugs.alpinelinux.org"

musl-1.1.9-r5
libv8 (= 3.16.14.6)
therubyracer (0.12.1)

So, no we're not using edge Alpine.

[envygeeks]

Hmmmm... that's the same versions we tried with our Discourse image that ended up segfaulting on Musl here is where we get the segfault: https://github.com/discourse/discourse/blob/a8edc982762d14bd01dc0b2964909c1fb6103deb/lib/pretty_text.rb#L176

I will try to recompile today.