Heroku / Rails build

[edborden]

Any guidance on getting this running on Heroku on Rails? I need a service that can convert latex to png via an API, would this be a good engine for that? I'm not really sure how to get it running with all of the external dependencies, how would Heroku pick them up?

[gjtorikian]

Hey @edborden, check out https://github.com/gjtorikian/math-web. It's a bit out-of-date, but it's a server that uses mathematical to output SVG (or PNG), given an equation. Let me know if that works for you.

[edborden]

I pulled that repository into Heroku and deployed and got:

-----> Ruby app detected
-----> Compiling Ruby/Rack
-----> Using Ruby version: ruby-2.0.0
-----> Installing dependencies using bundler 1.9.7
       Running: bundle install --without development:test --path vendor/bundle --binstubs vendor/bundle/bin -j4 --deployment
       Fetching gem metadata from https://rubygems.org/..........
       Fetching version metadata from https://rubygems.org/..
       Rubygems 2.0.14 is not threadsafe, so your gems must be installed one at a time. Upgrade to Rubygems 2.1.0 or higher to enable parallel gem installation.
       Installing rake 10.4.2
       Installing kgio 2.9.2
       Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
       /tmp/build_0c4c49cd11a6459a45a8bd1bbef26307/edborden-math-web-f6da723/vendor/ruby-2.0.0/bin/ruby extconf.rb
       checking for main() in -lxml2... yes
       checking for libxml/tree.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       checking for libxml/parser.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       checking for libxml/xpath.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       checking for libxml/xpathInternals.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       make: *** No targets specified and no makefile found.  Stop.
       checking for main() in -lpangocairo-1.0... no
       Package pango was not found in the pkg-config search path.
       Perhaps you should add the directory containing `pango.pc'
       to the PKG_CONFIG_PATH environment variable
       No package 'pango' found
       Package pango was not found in the pkg-config search path.
       Perhaps you should add the directory containing `pango.pc'
       to the PKG_CONFIG_PATH environment variable
       No package 'pango' found
       creating Makefile
       make "DESTDIR="
       compiling lsmsvgclippathelement.c
       In file included from ./lsmsvgtypes.h:27:0,
       from ./lsmsvgclippathelement.h:27,
       from lsmsvgclippathelement.c:24:
       ./lsmsvgenums.h:27:25: fatal error: glib-object.h: No such file or directory
       #include <glib-object.h>
       ^
       compilation terminated.
       make: *** [lsmsvgclippathelement.o] Error 1
       Gem files will remain installed in /tmp/build_0c4c49cd11a6459a45a8bd1bbef26307/edborden-math-web-f6da723/vendor/bundle/ruby/2.0.0/gems/mathematical-1.2.0 for inspection.
       Results logged to /tmp/build_0c4c49cd11a6459a45a8bd1bbef26307/edborden-math-web-f6da723/vendor/bundle/ruby/2.0.0/gems/mathematical-1.2.0/ext/mathematical/gem_make.out
       An error occurred while installing mathematical (1.2.0), and Bundler cannot
       continue.
       Make sure that `gem install mathematical -v '1.2.0'` succeeds before bundling.
       Bundler Output: Fetching gem metadata from https://rubygems.org/..........
       Fetching version metadata from https://rubygems.org/..
       Rubygems 2.0.14 is not threadsafe, so your gems must be installed one at a time. Upgrade to Rubygems 2.1.0 or higher to enable parallel gem installation.
       Installing rake 10.4.2
       Installing kgio 2.9.2

       Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

       /tmp/build_0c4c49cd11a6459a45a8bd1bbef26307/edborden-math-web-f6da723/vendor/ruby-2.0.0/bin/ruby extconf.rb
       checking for main() in -lxml2... yes
       checking for libxml/tree.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       checking for libxml/parser.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       checking for libxml/xpath.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       checking for libxml/xpathInternals.h in /include/libxml2,/usr/include/libxml2,/usr/local/include/libxml2... yes
       make: *** No targets specified and no makefile found.  Stop.
       checking for main() in -lpangocairo-1.0... no
       Package pango was not found in the pkg-config search path.
       Perhaps you should add the directory containing `pango.pc'
       to the PKG_CONFIG_PATH environment variable
       No package 'pango' found
       Package pango was not found in the pkg-config search path.
       Perhaps you should add the directory containing `pango.pc'
       to the PKG_CONFIG_PATH environment variable
       No package 'pango' found
       creating Makefile

       make "DESTDIR="
       compiling lsmsvgclippathelement.c
       In file included from ./lsmsvgtypes.h:27:0,
       from ./lsmsvgclippathelement.h:27,
       from lsmsvgclippathelement.c:24:
       ./lsmsvgenums.h:27:25: fatal error: glib-object.h: No such file or directory
       #include <glib-object.h>
       ^
       compilation terminated.
       make: *** [lsmsvgclippathelement.o] Error 1

       Gem files will remain installed in /tmp/build_0c4c49cd11a6459a45a8bd1bbef26307/edborden-math-web-f6da723/vendor/bundle/ruby/2.0.0/gems/mathematical-1.2.0 for inspection.
       Results logged to /tmp/build_0c4c49cd11a6459a45a8bd1bbef26307/edborden-math-web-f6da723/vendor/bundle/ruby/2.0.0/gems/mathematical-1.2.0/ext/mathematical/gem_make.out
       An error occurred while installing mathematical (1.2.0), and Bundler cannot
       continue.
       Make sure that `gem install mathematical -v '1.2.0'` succeeds before bundling.
 !
 !     Failed to install gems via Bundler.
 !
 !     Push rejected, failed to compile Ruby app

[gjtorikian]

Ah, yeah, I had to spin up a DigitalOcean server to support this, because Heroku didn't have the appropriate C libraries to pull it off. At least, at the time (~a year ago), I couldn't figure it out. Maybe things have changes?

[edborden]

I saw you have a repository for a pango buildpack, did that not work?

[gjtorikian]

No. :cry: Again, this was all about a year ago, so maybe the circumstances have changed.

[schneems]

Heroku has libpango but not the dev files on it. You can install them using the apt buildpack (https://elements.heroku.com/buildpacks/heroku/heroku-buildpack-apt) and this package libpango1.0-dev found from https://packages.ubuntu.com/search?keywords=pango&searchon=names&suite=bionic&section=all.

You can see it work on a docker image:

docker run -it --rm heroku/heroku:18-build  bash

Then

apt-get update
apt-get install libpango1.0-dev

After that, then i'm able to get a result from pkg-config:

root@0ab4575f64e7:/# pkg-config --static --libs glib-2.0 gdk-pixbuf-2.0 cairo pango
-lgdk_pixbuf-2.0 -lm -lgmodule-2.0 -pthread -ldl -lpng16 -lm -lz -lm -lcairo -lz -lpixman-1 -lfontconfig -lexpat -lfreetype -lexpat -lfreetype -lpng16 -lm -lz -lm -lz -lxcb-shm -lxcb-render -lXrender -lXext -lX11 -lpthread -lxcb -lXau -lXdmcp -lpango-1.0 -lm -lgobject-2.0 -lffi -lglib-2.0 -pthread -lpcre -pthread

So that might be enough to get you going.

Also to note, we recommend against statically linking against system binaries. If there were a security update and the gem you're using is statically compiled then it won't receive the security updates after we've updated our packages on the stack image.