[ADR] Group projects together in a monorepo

Context

It turns out that putting everything in a separate repositories has too many disadvantages e.g.:

  • Key management
  • User rights
  • Doing updates (e.g. library updates need to be done over multiple )
  • ES lint rules

The initial idea was that this will help the maintenance of the software. It turns out that a maintainer has a group of repository in practice.

Decision

For OSCD-Components, we should make use of the Package-based Repo. Each component has it's own `package.json` File and can be individually developed, tested, compiled and published.


Motivations to run with a monorepository instead of seperate repositories

  • One code owner to rule them all
  • One storybook for easy checking/testing components
  • 1 NPM token
  • Easy copying
  • Lower workload on the developers
  • 1 ESlint


Technology

A good approach for monorepos is [`Lerna`](https://lerna.js.org/), in combination with [`Nx`](https://nx.dev). Other possible tools are [`TurboRepo`](https://turbo.build/) and [`Rush`](https://rushjs.io/).


Factors to consider to group components in the same repository:

  • Shared functionality
  • Synergy
  • Maintainability
  • Activity


It's good to know that a monorepository is not the same as a monolith. 

✋  Monorepo  ≠  is different fromMonolith

A good monorepo is the opposite of monolithic! Read more about this and other misconceptions in the article on  [“Misconceptions about Monorepos: Monorepo != Monolith”](https://blog.nrwl.io/misconceptions-about-monorepos-monorepo-monolith-df1250d4b03c "Misconceptions about Monorepos: Monorepo != Monolith").


There are 3 types of monorepos:

* Integrated Repos
* Package-based Repos
* Standalone Apps


Codeowners can be used to separate the owners of different components.


Core plugins can be grouped together in multiple monorepos


PluginGroupRepository
@openscd/oscd-openFile-handling
@openscd/oscd-newFile-handling
@openscd/oscd-saveFile-handling
@openscd/oscd-validate-templateValidating
@openscd/oscd-validate-schemaValidating
@openscd/oscd-import-iedIED
@openscd/oscd-compare-iedIED
@openscd/oscd-virtual-iedIED
@openscd/oscd-substation-editorEditor
@openscd/oscd-ied-editorEditor
@openscd/oscd-template-

Packages using the monorepo approach:

Consequences

Disadvantages for combining different packages into a monorepo

  • A monorepo has less authorization rules.
    • If you can access one package in the monorepo, you can access them all
  • Git history will become more cluttered in a monorepo
  • Maintainer ship on a single package in a monorepo can become more of a hassle
  • 1 maintainers for all compontents (mitigation: can be splitup in multiple mono repositories to make it manageble)
  • Risk of overlapping (migitation: can be enforced by Lerna)