securerandom.rb:75:in `urandom': failed to get urandom (RuntimeError)

[dblock]

I am using dokku, which uses herokuish, which uses heroku-buildpack-ruby (v240). I did a dokku upgrade via apt (Ubuntu, dokku version 0.19.12) and all my deploys fail with this:

-----> Ruby app detected
remote: /tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/securerandom.rb:75:in `urandom': failed to get urandom (RuntimeError)
remote: 	from /tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/securerandom.rb:75:in `singleton class'
remote: 	from /tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/securerandom.rb:42:in `<module:SecureRandom>'
remote: 	from /tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/securerandom.rb:41:in `<top (required)>'
remote: 	from <internal:/tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
remote: 	from <internal:/tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
remote: 	from /tmp/buildpacks/01_buildpack-ruby/lib/language_pack/rails41.rb:1:in `<top (required)>'
remote: 	from <internal:/tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
remote: 	from <internal:/tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
remote: 	from /tmp/buildpacks/01_buildpack-ruby/lib/language_pack.rb:44:in `<top (required)>'
remote: 	from <internal:/tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
remote: 	from <internal:/tmp/tmp.QJdgokaA3p/lib/ruby/3.1.0/rubygems/core_ext/kernel_require.rb>:85:in `require'
remote: 	from /tmp/buildpacks/01_buildpack-ruby/bin/support/ruby_compile:11:in `<main>'
remote: 2022/06/12 22:02:56 exit status 1 

It also fails to ps:rebuild, but doesn’t output an error.

Setup:

Linux dblock-plum 3.13.0-71-generic #114-Ubuntu SMP Tue Dec 1 02:34:22 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

# docker version
Client:
 Version:      17.05.0-ce
 API version:  1.29
 Go version:   go1.7.5
 Git commit:   89658be
 Built:        Thu May  4 22:06:06 2017
 OS/Arch:      linux/amd64

Server:
 Version:      17.05.0-ce
 API version:  1.29 (minimum version 1.12)
 Go version:   go1.7.5
 Git commit:   89658be
 Built:        Thu May  4 22:06:06 2017
 OS/Arch:      linux/amd64
 Experimental: false

# docker run -ti gliderlabs/herokuish:latest herokuish version
herokuish: 0.5.36
buildpacks:
  heroku-buildpack-multi     v1.2.0
  heroku-buildpack-ruby      v240
  heroku-buildpack-nodejs    v196
  heroku-buildpack-clojure   v87
  heroku-buildpack-python    v211
  heroku-buildpack-java      v70
  heroku-buildpack-gradle    v36
  heroku-buildpack-scala     v92
  heroku-buildpack-play      v26
  heroku-buildpack-php       v218
  heroku-buildpack-go        v162
  heroku-buildpack-nginx     v16
  buildpack-null             v3

I'm stuck. Ruby 3.1.0 works fine on the machine, including SecureRandom.hex and SecureRandom.bytes(n).

I don't know how to downgrade the buildpack to see in which version this started happening, would be willing to try.

Update: I downgraded herokuish with sudo apt install herokuish=0.5.34 which used heroku-buildpack-ruby v236 and the problem went away. Hope this helps narrow it down.

[edmorley]

Searching I came across solectrus/hosting/issues/4 which suggests this might be related to ulimits or old kernel versions?

Also Docker 17.05.0-ce is very old - have you tried newer? Even Ubuntu's own APT-provided Docker are all newer than this :-)

[edmorley]

Closing since this seems like an issue with the machine Dokku is being run on.