move helm chart to fastcs standard

Author: gilesknap

Charts/README.md

@@ -0,0 +1,70 @@
+# Charts
+
+This directory contains Helm charts for deploying FastCS services.
+
+## Github Actions
+
+This folder works in tandem with [_helm.yml](../.github/workflows/_helm.yml) github actions workflow which:
+
+- Validates the stricter form of SemVer tag that helm requires.
+- Finds all subfolders in the `Charts` directory and packages them as Helm charts.
+- Publishes the packaged charts to ghcr.io/${{github.repository_owner }}/charts/CHART_NAME
+- Uploads the contents of /schemas to artifacts (meaning they will be published to the release)
+
+This standalone Helm related workflow is independent of the rest of the workflows except that the _pypi workflow has _helm added to its `needs` in `ci.yml`, making sure we only publish to pypi with valid SemVer tags.
+
+## Schema Generation
+
+Schema generation for charts' `values.yaml` is handled by [helm-values-schema-json](https://github.com/losisin/helm-values-schema-json). Which is in turn controlled by annotations in the default [values.yaml](fastcs/values.yaml) file.
+
+The generated schema file will be called `values.schema.json` and will be placed in the same directory as the `values.yaml` file and commited to the repo. This is done automatically by a [pre-commit hook](https://github.com/DiamondLightSource/FastCS/blob/8232393b38cc8e0eee00680e95c2ce06e7983ba6/.pre-commit-config.yaml#L27-L33). Therefore, when developing charts you can update schemas with:
+
+```bash
+git add . ; pre-commit
+# or
+pre-commit run --all-files
+```
+
+
+Note that this standard name for the schema file means that it is packaged up with the helm chart and available for schema checks in ArgoCD for example.
+
+## `schemas` folder
+
+The schemas folder allows us to declare the schemas we want to publish to the release.
+
+It should contain:
+
+- A symlink to each of the `values.schema.json` files in the subfolders of `Charts`. The symlink should have a unique name, e.g. `fastcs-values.schema.json`, thus allowing multiple schemas to be published per repo.
+- A service schema file which references the above and can be used to validate `values.yaml` in epics-containers services repos, where the these charts will be used as sub-charts. e.g. [fastcs-service.schema.json](../schemas/fastcs-service.schema.json)
+
+The service schema files are hand coded as they are extremely simple and unlikely to change.
+
+## Debuging/Development In-Cluster
+
+The `fastcs` helm chart has two variables to enable debugging/development in-cluster:
+
+- `editable`: When true:
+  - a PVC is created.
+  - The debug version of the container image is referenced.
+  - The contents of /workspaces and /venv are copied into the PVC.
+  - The venv from the debug image is an editable install of the project source code in /workspaces.
+  - The PVC folders are mounted over the corresponding folders in the container.
+- `autostart`:
+  - When false, the container starts with PID 1 as sleep infinity.
+  - When true, the container starts with its normal entrypoint.
+
+In combination these flags can be used to debug or develop in-cluster.
+
+These features will be accessed via `ec`. See https://github.com/epics-containers/edge-containers-cli/issues/207
+
+This script will:
+
+- Inspect the values of `editable` and `autostart` in the `values.yaml` file of the specified IOC (TODO: at present it uses the p47-services source code to do so but this should be determined from the cluster in future).
+- Port forward the debugpy port (5678) from the pod to localhost.
+- If editable is true, it will mount the PVC locally using pv-mounter and open VSCode to the /workspaces/xxx folder.
+- If autostart is false, it will exec into the container and launch debugpy to run the main program.
+- If autostart is true, it will exec into the container and attach debugpy to PID 1.
+
+This then allows you to attach VSCode to debugpy in the cluster container and if 'editable' is true, edit the source code in VSCode and have the changes reflected.
+
+To attach to debugpy the following launch.json configuration is supplied in the [fastcs-example project](https://github.com/DiamondLightSource/fastcs-example/blob/77daed5f5a2bd01ab4c0e1d8c812e8754b254674/.vscode/launch.json#L7-L22). (this will also go in python-copier-template in future).