crash during check external_links

[iay]

bundle exec nanoc check elinks causes exception

Details

kite:site iay$ bundle exec nanoc check elinks
Loading site… done
  Running check external_links…   
Captain! We’ve been hit!

TypeError: no implicit conversion of nil into String

  0. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/bundler/gems/nanoc-6b5b66edc64f/nanoc/lib/nanoc/checking/checks/external_links.rb:84:in `+'
  1. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/bundler/gems/nanoc-6b5b66edc64f/nanoc/lib/nanoc/checking/checks/external_links.rb:84:in `block in validate'
  2. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/bundler/gems/nanoc-6b5b66edc64f/nanoc/lib/nanoc/checking/checks/external_links.rb:62:in `times'
  3. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/bundler/gems/nanoc-6b5b66edc64f/nanoc/lib/nanoc/checking/checks/external_links.rb:62:in `validate'
  4. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/bundler/gems/nanoc-6b5b66edc64f/nanoc/lib/nanoc/checking/checks/external_links.rb:40:in `block in select_invalid'
  5. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/gems/parallel-1.12.1/lib/parallel.rb:484:in `call_with_index'
  6. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/gems/parallel-1.12.1/lib/parallel.rb:342:in `block (2 levels) in work_in_threads'
  7. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/gems/parallel-1.12.1/lib/parallel.rb:495:in `with_instrumentation'
  8. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/gems/parallel-1.12.1/lib/parallel.rb:341:in `block in work_in_threads'
  9. /Volumes/Cased/git/iay/iay/site/vendor/ruby/2.4.0/gems/parallel-1.12.1/lib/parallel.rb:206:in `block (2 levels) in in_threads'

Crash log

https://gist.github.com/iay/2fc13b5b7b406a6b50ef998b7023ef76

[iay]

You can see from the traceback that this is the gitlab head from a couple of days ago.

[denisdefreyne]

Is this an exception that occurs consistently?

Line 84 of external_links.rb says

location = base_url.to_s + location

That TypeError would occur when location is nil, which can only happen when res['Location'] is nil. That’d be for a HTTP 3xx response without a Location header, which can happen (e.g. for 300 Multiple Choices).

At the very least, Nanoc should check the presence of the Location header, before attempting to do anything with it!

[iay]

Yes, it seems to be consistent. I will try and add some kind of puts to nail down the URL in question.

[iay]

This seems to be one of the links that is killing things:

kite:site iay$ curl -I https://movabletype.org/default_styles.shtml
HTTP/1.1 302 Moved Temporarily
Content-Type: text/html
Date: Tue, 23 Jan 2018 08:34:27 GMT
Server: nginx
X-Frame-Options: SAMEORIGIN
Connection: keep-alive

[denisdefreyne]

That HTTP response is weird:

1. HTTP/1.1 defines 302 as 302 Found, not 302 Moved Temporarily. It seems to mix HTTP/1.0 and HTTP/1.1.

2. The Location header is supposed to be present.

Not sure what to do in this case. Probably not error, and treat this situation as OK? An error in this case would not provide anything actionable.

[denisdefreyne]

#1302 has a fix.