Ruby buildpack failed to analyze Gemfile with ruby syntax about ruby-buildpack

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/121730559

The labels on this github issue will be updated when the story is started.

[flavorjones]

@liuweichu Have you tried using ::Gem instead of plain-old Gem?

If not, please do and let us know how you get on.

[flavorjones]

Actually, this log message:

sh: 1: Syntax error: EOF in backquote substitution

is not good. Something else is going on. @RochesterinNYC any ideas?

[cf-buildpacks-eng]

@liuweichu Thanks, we have added both of your examples to our test suite. We are now leveraging Bundler's DSL evaluator directly, and so the buildpack will correctly handle any Gemfile which is valid for Bundler.

Could you please push using the develop branch (eg. cf push test -b https://github.com/cloudfoundry/ruby-buildpack.git#develop) and tell us either way. If it works we will close this issue.

[liuweichu]

@cf-buildpacks-eng
Tested on develop branch, it works!
Thank you for the quick respond.

Close this issue.

[liuweichu]

@flavorjones Hi, I'm not sure what is ::Gem. Could you please give me some more explanation?

[allomov]

@liuweichu two double-colon tells ruby to start search for constant in global scope. You can find some details here.

I already created a PR to solve this issue #57, but it was not fully accepted. This particular problem is caused, because const_missing in LanguagePack::RubySemverVersion doesn't return anything and ruby returns nil as a result of such methods (link to code). And this nil causes undefined method ... for nil:NilClass error in your case.

I think, that :: will help in your case.

[allomov]

@liuweichu looks like this commit should fix this issue in following ruby-buildpack version.

You can also use develop branch to try this fixes right now, just push your app in the following way:

cf push <app-name> -b https://github.com/cloudfoundry/ruby-buildpack#develop

[liuweichu]

@allomov Thanks for telling me a new ruby trick 😃
I tested the develop against redmine's Gemfile, and it works perfectly.