Imagine you have a single code base which has multiple application within it (here 3 applications Nginx, Node.JS and Ruby application), or you are following Google's Monorepo structure.
In that case how do you manage that with Heroku (Incl pipeline and Review Apps)?
We will use heroku-buildpack-monorepo which uses heroku-buildpack-multi-procfile, This POC has 3 applications (Nginx Reverse Proxy, Node.JS getting started application, Ruby getting started application):
heroku create -a mono-nginx-app-stgheroku create -a mono-node-app-stgheroku create -a mono-ruby-app-stg
Set relative path of application root directory (Where is Procfile) in application APP_BASE config var
heroku config:set -a mono-nginx-app-stg APP_BASE=nginx-app/heroku config:set -a mono-node-app-stg APP_BASE=node-app/heroku config:set -a mono-ruby-app-stg APP_BASE=ruby-app/
heroku buildpacks:add -i 1 -a mono-nginx-app-stg https://github.com/lstoll/heroku-buildpack-monorepoheroku buildpacks:add -i 1 -a mono-node-app-stg https://github.com/lstoll/heroku-buildpack-monorepoheroku buildpacks:add -i 1 -a mono-ruby-app-stg https://github.com/lstoll/heroku-buildpack-monorepo
You can either use Github integration (Heroku Github Deploys) or you can push code to Heroku git using following commands:
git push [email protected]:mono-nginx-app-stg mastergit push [email protected]:mono-node-app-stg mastergit push [email protected]:mono-ruby-app-stg master
When application builds, buildpack (heroku-buildpack-monorepo) will copy Procfile from directory defined in APP_BASE config vars into /app directory of Heoku application.
You can create pipeline from Heroku dashboard or using CLI command, Check more details here.
heroku pipelines:create -a mono-nginx-app-stg
? Pipeline name: mono-pipeline
? Stage of mono-nginx-app-stg: staging
Creating example-pipeline pipeline... done
Adding mono-nginx-app-stg to mono-pipeline pipeline as staging... done
Note that the command must specify an existing app that you want to add to the pipeline.
The CLI prompts you to specify a name for the pipeline and a stage for the app you’re adding to it (development, staging, or production)
You can connect your diffrent branch to diffrent environments of pipeline and can configure the automatic deploys.
As we already set config var so when new build take place buildpack will automatically identify which code to deploy in which applicaion.
Note: Only builds will set the proper Procfile, promoting a slug downstream will not trigger a build, and therefore will not look at the environment variable and act accordingly. Make sure that the proper Procfile is referenced all the way upstream to the first stage that builds.
To get monorepo work with Review Apps is bit tricky as there is no way to configure app.json for multiple directories, only one app.json schema is allowed, you can specify all the required buildpack and addons for every applications into one app.json schema, check example app.json.
Now question is how to handle multiple buildpack for each codebase? (because If you don't have proper configuration files (like packge.json, Gemfile, requirements.txt) in your project directory language buildpack will throw error at build time).
So in this example we used 2 language specific buildpacks Node.JS (Requires package.json) and Ruby (Requires Gemfile), To handle this, added package.json and Gemfile (Without any configurations) in nginx-app, added Gemfile (Without any configurations) in node-app and added package.json (without any configuratios) in ruby-app.
Note: Don't forgot to generate Gemfile.lock (It can be done by bundle install).
So this is tricky part, you need to add or update APP_BASE config var at the pipeline's setting before creating Review App, which will be injected into the review app when it is created and buildpack will identify which codebase to consider.
Note: You need to specify APP_BASE as required to true (Which will indicate config var is required for app to function) in app.json file.
Dhaval Thakkar ([email protected])
Special thanks to Andrew Gwozdziewycz, Cyril David and Lincoln Stoll for creating awesome buildpack to handle monorepo structure on Heroku.