Using MySQL 5.7 libraries on Heroku

README.md

Edit 2021-02-21: I've confirmed this solution works with both heroku-18 and heroku-20 stacks.

---

What follows is my solution for having mysql2 gem compiled and working against MySQL v5.7 (rather than v8+) on the heroku-20 stack. This is how I've managed to make it work:

• Add the apt buildstack ahead of your standard buildpack (in my case, that's Ruby):

$ heroku buildpacks:add --index 1 heroku-community/apt

• Create an Aptfile in the root of your project, and add the MySQL 5.7 client tools (as a URL for the deb file) to it:

# in Aptfile:
https://cdn.mysql.com/Downloads/MySQL-5.7/libmysqlclient-dev_5.7.32-1ubuntu18.04_amd64.deb

• Ensure that the mysql2 gem compiles using the Apt-provided library (via BUNDLE_BUILD__MYSQL2) and that, when the library loads, it knows how to find libstdc++ (via LD_PRELOAD). I've found that LD_PRELOAD isn't already set to anything in my apps - but yours may be different, so do check before running this command.

$ heroku config:set \
  LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libstdc++.so.6 \
  BUNDLE_BUILD__MYSQL2=--with-mysql-config

• Update your app to use the heroku-20 stack if you haven't already:

$ heroku stack:set heroku-20

• Deploy this Aptfile to your app, and it should work. If the gems are cached from a previous build (for example, if you had already changed the stack and deployed other changes), you will need to clear your build cache prior to deploying, to ensure the mysql2 gem is recompiled.

If anyone has any questions or thoughts about this, do let me know.

Hi Pat,

We've a container-stack based Rails Heroku app, and our CI is heroku-16 stack. I've followed the instructions here, set the stack in app.json to heroku-20 for the test env (tried heroku-18 at some point as well) and set the LD_PRELOAD & BUNDLE_BUILD__MYSQL2 ENV variables (in app.json for test env). While the test setup phase is going fine over the CI, some Thinking Sphinx tests are now failing and I'm not sure why. I should mention we've inherited this app and our team has small-to-none experience working with TS, so we've no idea where to look for more exactly. Here's more info:

Ruby:2.7.2-buster
mysql2 0.5.3
pg 1.2.3
thinking-sphinx 5.0.0
flying-sphinx 2.2.0
activerecord 5.2.4.4

 test_0002_Searching by invalid filter type raises error when NOT in production#SomeTest (174.32s)
        ThinkingSphinx::SphinxError expected but nothing was raised.
        test/integration/some_test.rb:31:in `block in <class:SomeTest>'
�[1000D�[K FAIL["test_0001_Searching by invalid filter type returns empty results page when in production", #<Minitest::Reporters::Suite:0x000056397a3864e0 @name="SomeTest">, 178.64281626208685]
 test_0001_Searching by invalid filter type returns empty results page when in production#SomeTest (178.64s)
        Expected at least 1 element matching ".qwerty", found 0..
        Expected 0 to be >= 1.
        test/integration/some_test.rb:26:in `block in <class:SomeTest>'

Tried specifying the engine/version, tests still fail. They passed before doing this update.

I've no idea where to look at this point, so what I guess I'm looking for are some directions, please. Thanks!

Hi Alex - I'm not sure what the cause of this issue is, but perhaps you can share that test (and the corresponding index definitions) with me at http://support.flying-sphinx.com? It'll be easier to discuss the specifics there :)

Hi Pat. I opened a ticket a few days ago, but there's no reply from anyone yet. Hoping to hear from someone soon to get this issue fixed :) Cheers

Quick update, the URL for the download changed. If you get a 404 error from curl (22), you need to update to:

https://dev.mysql.com/get/Downloads/MySQL-5.7/libmysqlclient-dev_5.7.32-1ubuntu18.04_amd64.deb