docker-compose build fails to build 'streaming'

[jemus42]

[…]
Installing rack-protection 1.5.3
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

current directory:
/mastodon/vendor/bundle/ruby/2.4.0/gems/nio4r-2.0.0/ext/nio4r
/usr/local/bin/ruby -r ./siteconf20170420-43-1ee9c4k.rb extconf.rb
Out of memory - /usr/local/bin/ruby -r ./siteconf20170420-43-1ee9c4k.rb
extconf.rb 2>&1

Gem files will remain installed in
/mastodon/vendor/bundle/ruby/2.4.0/gems/nio4r-2.0.0 for inspection.
Results logged to
/mastodon/vendor/bundle/ruby/2.4.0/extensions/x86_64-linux/2.4.0/nio4r-2.0.0/gem_make.out

An error occurred while installing nio4r (2.0.0), and Bundler cannot continue.
Make sure that `gem install nio4r -v '2.0.0'` succeeds before bundling.
ERROR: Service 'streaming' failed to build: The command '/bin/sh -c echo "@edge https://nl.alpinelinux.org/alpine/edge/main" >> /etc/apk/repositories  && BUILD_DEPS="     postgresql-dev     libxml2-dev     libxslt-dev     build-base"  && apk -U upgrade && apk add     $BUILD_DEPS     nodejs@edge     nodejs-npm@edge     libpq     libxml2     libxslt     ffmpeg     file     imagemagick@edge  && npm install -g npm@3 && npm install -g yarn  && bundle install --deployment --without test development  && yarn --ignore-optional  && yarn cache clean  && npm -g cache clean  && apk del $BUILD_DEPS  && rm -rf /tmp/* /var/cache/apk/*' returned a non-zero code: 5

System: Linux (hostname) 4.8.0-41-generic #44-Ubuntu SMP Fri Mar 3 15:27:17 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux, freshly set up VPS.

Error appears both on v.1.2.2 and latest master.

---

• I searched or browsed the repo’s other issues to ensure this is not a duplicate.
• This bug happens on a tagged release and not on master (If you're a user, don't worry about this).

[jemus42]

Appears to be an out-of-memory thing. Looks like the small test VPS is too small to test.