Error on newlines in sidekiq-cluster arguments
When using Helm charts, which are YAML files, it's relatively easy to
accidentally include a newline in the Sidekiq arguments. This will
typically be a trailing newline, which shouldn't be a problem, except
that in our cloud-native deployment we launch Sidekiq using the command
given by sidekiq-cluster --dryrun (to avoid having the wrapper
process), so we effectively do:
$(bin/sidekiq-cluster --dryrun $ARGS)Ruby's Shellwords.escape quotes newlines as '\n':
https://github.com/ruby/shellwords/blob/v0.1.0/lib/shellwords.rb#L161-L163
When those are parsed back in the arguments array we get foo'\n' for
an original argument of foo\n. Then, when we apply splitting, we get
foo' and ' as two separate arguments.
The quoting here is quite complicated but the below demonstrates (in Bash) what's happening:
$ ruby -e 'p ARGV; p ARGV.first.split' "foo'"$'\n'"'"
["foo'\n'"]
["foo'", "'"]If we did care about newlines in this argument array, the solution would be more involved. But we don't, because they are never valid, so we can just error when we encounter them.
This came from https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/14002.