Monorepos

What is monorepo?

A VCS repository with more than one project

Project: usually library or application, but may be really anything

Naming: projects/sub-projects/modules/sub-modules

Widely adopted by huge companies (like Google, Facebook, Twitter)

Works for relatively small repos too

It's ok to think of it as a fancy name for multi-module builds

May contain all company code

May contain only some parts of a company code

Example: Kafka

Modules organization

commons
|- basic-utils
|- models
|- database-interactions
|-...
collectors

|- commons
|- youtube

|- twitter
|- ...

aggregators

|- commons

|- youtube

|- twitter
|- ...

commons
|- basic-utils
|- models
|- database-interactions
|-...
youtube

|- commons
|- collector

|- aggregator

twitter

|- commons

|- collector

|- aggregator
...

Benefits

3. Super easy code sharing

1. Single source of truth

  • Fearless refactorings (and code deletion)

2. Everything is up-to-date in the code

4. Works not only for code

  • Configuration
  • DB migrations
  • Deploy scripts
  • Everything is at hand
  • Docs

Challenges

1. Reproducible builds (for deploying old versions)

2. Build time

3. Remote caching

2. Rare apps deploys may lead to a problems

3. Hard to not touch old code

1. Suitable build tool

4. Build complexity (extensibility of a build tool)

4. Hard to share code with other teams

Why I think monorepo will work for us

1. Relatively small codebase (so no big scale problems)

2. Team code is pretty isolated (no code sharing with other teams)

3. A lot of stuff are already shared, or should be shared across many projects

4. Monorepo is a good place for DB management stuff

What we will have to  consider

1. How will it work with an infra-as-code approach?

2. What build tool will we use?

3. How to migrate our existing code to monorepo and not get mad?

1. gradle

2. bazel

Thank you!

Monorepos

By Yury Badalyants

Monorepos

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