[changelog skip] Fix \n in export path

[schneems]

The command which returns a newline which was being put in the PATH and then exported to the export file:

which node: "/tmp/build_d21ec1d0a2e7e9466b95cd2f7f79b41a/.heroku/node/bin/node\n"

Would cause this to be in the PATH:

remote: export PATH=/tmp/build_449e75fdca9780bfa7f33fac3b86065e/./vendor/bundle/bin:/tmp/build_449e75fdca9780bfa7f33fac3b86065e/./vendor/bundle/ruby/2.6.0/bin:/tmp/build_449e75fdca9780bfa7f33fac3b86065e/vendor/ruby-2.6.2/bin:/tmp/tmp.ly4bnGG8nm/bin/:/tmp/build_449e75fdca9780bfa7f33fac3b86065e/.heroku/node/bin:/tmp/build_449e75fdca9780bfa7f33fac3b86065e/.heroku/yarn/bin:/usr/local/bin:/usr/bin:/bin:/tmp/codon/vendor/bin:/tmp/build_449e75fdca9780bfa7f33fac3b86065e/node_modules/.bin:/tmp/build_449e75fdca9780bfa7f33fac3b86065e/.heroku/node/bin/node
remote: :/tmp/build_449e75fdca9780bfa7f33fac3b86065e/bin:/usr/local/bin:/usr/bin:/bin:$PATH

This causes the multi buildpack to fail #963, but only the multi buildpack. Error is:

remote: /tmp/buildpackYYwZE/export: line 2: :/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/bin:/usr/local/bin:/usr/bin:/bin:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/./vendor/bundle/bin:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/./vendor/bundle/ruby/2.6.0/bin:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/vendor/ruby-2.6.5/bin:/tmp/tmp.behzAImwsj/bin/:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/.heroku/node/bin:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/.heroku/yarn/bin:/usr/local/bin:/usr/bin:/bin:/tmp/codon/vendor/bin:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/node_modules/.bin:/tmp/build_71238ae8789a5e65c5afca4e8abc6c3a/.heroku/node/bin/node: No such file or directory

Even though this is the bug, it has been in the ruby buildpack for some time. Something in #888 introduced a failure mode.

Since multi-buildpack is deprecated and unmaintained I don't want to add an automated test here. You can manually reproduce the failure by running:

cd /tmp
dir_name=$(ruby -e "require 'securerandom'; puts SecureRandom.hex")
mkdir $dir_name
cd $dir_name
echo "source 'https://rubygems.org'" > Gemfile
bundle install
git init .
git add .
git commit -m first
echo '{ "engines" : { "node": "8.9.4" } }' > package.json
heroku create
heroku buildpacks:set https://github.com/heroku/heroku-buildpack-multi
echo "https://github.com/heroku/heroku-buildpack-nodejs.git" >> .buildpacks
echo "https://github.com/heroku/heroku-buildpack-ruby" >> .buildpacks
git add . ; git commit -m next
git push heroku master

You can get it to pass by running

rm .buildpacks
echo "https://github.com/heroku/heroku-buildpack-nodejs.git" >> .buildpacks
echo "https://github.com/heroku/heroku-buildpack-ruby#schneems/fix-node-which" >> .buildpacks

Which points the app at this PR.

[edmorley]

Out of curiosity I had a quick look through #888 but couldn't see an obvious cause there that exposed this. Guess somewhat irrelevant given this was a real bug anyway :-)

[schneems]

Here's the export file before and after #888

Before #888

export GEM_PATH="/tmp/build_7150eb1767e7c0074cc51707f27954f0/vendor/bundle/ruby/2.6.0:$GEM_PATH"
export LANG=${LANG:-en_US.UTF-8}
export PATH="/tmp/build_7150eb1767e7c0074cc51707f27954f0/vendor/bundle/bin:/tmp/build_7150eb1767e7c0074cc51707f27954f0/vendor/bundle/ruby/2.6.0/bin:/tmp/build_7150eb1767e7c0074cc51707f27954f0/vendor/ruby-2.6.5/bin:/tmp/tmp.FwT0R4i7tn/bin/:/tmp/build_7150eb1767e7c0074cc51707f27954f0/.heroku/node/bin:/tmp/build_7150eb1767e7c0074cc51707f27954f0/.heroku/yarn/bin:/usr/local/bin:/usr/bin:/bin:/tmp/codon/vendor/bin:/tmp/build_7150eb1767e7c0074cc51707f27954f0/node_modules/.bin:/tmp/build_7150eb1767e7c0074cc51707f27954f0/.heroku/node/bin/node
:/tmp/build_7150eb1767e7c0074cc51707f27954f0/bin:/usr/local/bin:/usr/bin:/bin"

After #888

export PATH=/tmp/build_4ade224d4cac2630313b2c6ab0420e94/./vendor/bundle/bin:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/./vendor/bundle/ruby/2.6.0/bin:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/vendor/ruby-2.6.5/bin:/tmp/tmp.agFPALxbad/bin/:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/.heroku/node/bin:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/.heroku/yarn/bin:/usr/local/bin:/usr/bin:/bin:/tmp/codon/vendor/bin:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/node_modules/.bin:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/.heroku/node/bin/node
:/tmp/build_4ade224d4cac2630313b2c6ab0420e94/bin:/usr/local/bin:/usr/bin:/bin:$PATH
export GEM_PATH=/tmp/build_4ade224d4cac2630313b2c6ab0420e94/vendor/bundle/ruby/2.6.0:$GEM_PATH
export LANG=${LANG:-en_US.UTF-8}

While this PR fixes the immediate issue. The problem seems to be that the export file values were being quoted, but that functionality was quietly dropped and not caught by the tests.

I'm not sure why heroku buildpacks works but the multibuildpack does not, i'm guessing it's a difference between how the file is exec-d or parsed. I think we need to make sure values are quoted before we can deploy. Merging this PR in as an immediate fix

[schneems]

I've got a PR with a test and a fix to the described export quoting issue in #967