Move SOP for new repos to more fleshed out repository-structure doc (#137)

We want to describe the desired state, not just the steps for
new repos.

In particular a goal here is to flesh out how CI/testing should
work and lean into the pattern that our projects should provide
integration tests and how those should work.

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

README.md

@@ -13,7 +13,7 @@ This repository provides centralized configuration and automation for the
 
 ## Documentation
 
-- [New Repository Setup](docs/SOP-new-repository.md) - Steps for onboarding new repos
+- [Repository Structure](docs/repository-structure.md) - Organization-wide repository standards
 
 ## Renovate
 

docs/SOP-new-repository.md

@@ -0,0 +1,86 @@
+# Repository structure
+
+The bootc-dev organization contains a number of repositories. While not every
+repository will function in exactly in the same way, there are
+"baseline" configuration and procedures that should generally apply.
+
+## Maintainers
+
+There should be a `maintainers` team with the **Maintain** permission
+that is used by repositories by default.
+
+## Renovate
+
+The organization uses a centralized Renovate configuration managed from this
+repository. To enable Renovate on a new repository, create a `renovate.json`
+file in the repository root:
+
+```json
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "local>bootc-dev/infra:renovate-shared-config.json"
+  ]
+}
+```
+
+## PR gating and merging
+
+Each repository MUST enable the following settings via a branch protection rule for `main`:
+
+- Require a pull request before merging
+- Require approvals
+
+### required-checks
+
+Having some kind of CI is also required. Repositories SHOULD enable the automatic merge setting,
+and configure at least one gating CI check.
+
+The ["required-checks" pattern](https://github.com/bootc-dev/bootc/blob/main/.github/workflows/ci.yml)
+is where the repository configuration gates solely on that check which in turn gates on others, allowing easy dynamic
+reconfiguration of the required checks without requiring administrator intervention.
+
+## Language
+
+In this organization, Rust is preferred.
+
+## Developer experience
+
+Repositories SHOULD have a [Justfile](https://just.systems/) which acts as a development entry point. It
+is strongly encouraged to follow the pattern in [bootc Justfile](https://github.com/bootc-dev/bootc/blob/main/Justfile)
+where e.g. GitHub Actions mostly invoke `just <x>` so all CI flows are easily
+replicable outside of GHA.
+
+## Devcontainer
+
+Repositories SHOULD have a `.devcontainer.json` (one is synchronized by default from this repo)
+and key targets in the `Justfile` should run in that environment.
+
+## Unit and integration tests
+
+Any nontrivial code SHOULD have unit tests and integration tests. An integration test MUST
+be a separately built artifact that tests a production build in a "black box" fashion.
+
+### Integration test environments
+
+Integration tests SHOULD be flexible and adaptable. In particular, there are multiple
+"test suite runner environments" which our integration tests should work with.
+
+- [Debian autopkgtest](https://wiki.debian.org/autopkgtest)
+- [tmt](https://tmt.readthedocs.io/en/stable/) (and [Fedora CI](https://packit.dev/fedora-ci/))
+
+Privileged and destructive tests should be clearly distinct.
+
+At the current time, bootc has some "bridging" between a custom integration test suite
+and tmt. However, a pattern used in other repositories is to have an integration test
+binary written in Rust that uses `libtest-mimic` - in this pattern all tests are just
+part of a simple single binary.
+
+- [composefs-rs](https://github.com/composefs/composefs-rs/tree/main/crates/integration-tests)
+- [bcvk](https://github.com/bootc-dev/bcvk/blob/main/Justfile)
+
+### Future direction
+
+Goal: Convert all repositories to a pattern like this, and create reliable bridging
+between it and tmt and Debian autopkgtest. For example, support converting
+the tests into the relevant framework format.