Heroku Buildpack: Valgrind

This is the Heroku buildpack for Valgrind.

N.B.: there are probably better debugging approaches in most situations; this should be considered a last resort.

Getting Started

This buildpack installs Valgrind and some debug symbols alongside your code, allowing you to run your application in a dyno under Valgrind. It adds a shell function to your environment that is a thin wrapper for the valgrind command; you should be able to use it like valgrind itself.

First, change your application to run under Valgrind:

maciek@mothra:~/code/my-app$ git diff
diff --git a/Procfile b/Procfile
index 9d7d0d2..d5f3106 100644
--- a/Procfile
+++ b/Procfile
@@ -1,2 +1,2 @@
-web: node static/server.js
+web: valgrind node static/server.js
maciek@mothra:~/code/my-app$ git commit Procfile -m "Run under valgrind"

Then tail your application logs

git logs --tail --ps web --app my-app

and in a separate console, deploy to Heroku:

git push heroku master

As your app starts up, you will see the following output from Valgrind:

2016-08-25T19:00:34.675244+00:00 app[web.1]: ==6== Memcheck, a memory error detector
2016-08-25T19:00:34.675302+00:00 app[web.1]: ==6== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
2016-08-25T19:00:34.675308+00:00 app[web.1]: ==6== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
2016-08-25T19:00:34.675308+00:00 app[web.1]: ==6== Command: node static/server.js
2016-08-25T19:00:34.675309+00:00 app[web.1]: ==6==

If Valgrind finds any problems, you will see more output, similarly prefixed.

Note that Valgrind will considerably slow down your application, to the point you may hit the Heroku boot timeout. You may need to contact Support to have the limit increased (and after the limit is increased, you may need to deploy a new version of your app for it to pick up the new boot timeout).

THIS IS BETA SOFTWARE

Thanks for trying it out. If you find any problems, please report an issue and include your other buildpacks and any relevant output.

Note that for the moment, the buildpack output is very verbose to make it easier to track down errors.