pat-s 8e27bb9bae [Breaking] Add HA-support; switch to Deployment (#437)
# Changes

A big shoutout to @luhahn for all his work in #205 which served as the base for this PR.

## Documentation

- [x] After thinking for some time about it, I still prefer the distinct option (as started in #350), i.e. having a standalone "HA" doc under `docs/ha-setup.md` to not have a very long README (which is already quite long).
      Most of the information below should go into it with more details and explanations behind all of the individual components.

## Chart deps

~~- Adds `meilisearch` as a chart dependency for a HA-ready issue indexer. Only works with >= Gitea 1.20~~
~~- Adds `redis` as a chart dependency for a HA-ready session and queue store.~~
- Adds `redis-cluster` as a chart dependency for a HA-ready session and queue store (alternative to `redis`). Only works with >= Gitea 1.19.2.
- Removes `memcached` instead of `redis-cluster`
- Add `postgresql-ha` as default DB dep in favor of `postgres`

## Adds smart HA chart logic

The goal is to set smart config values that result in a HA-ready Gitea deployment if `replicaCount` > 1.

- If `replicaCount` > 1,
  - `gitea.config.session.PROVIDER` is automatically set to `redis-cluster`
  - `gitea.config.indexer.REPO_INDEXER_ENABLED` is automatically set to `false` unless the value is `elasticsearch` or `meilisearch`
  - `redis-cluster` is used for `[queue]` and `[cache]` and `[session]`mode or not

Configuration of external instances of `meilisearch` and `minio` are documented in a new markdown doc.

## Deployment vs Statefulset

Given all the discussions about this lately (#428), I think we could use both.
In the end, we do not have the requirement for a sequential pod scale up/scale down as it would happen in statefulsets.
On the other side, we do not have actual stateless pods as we are attaching a RWX to the deployment.
Yet I think because we do not have a leader-election requirement, spawning the pods as a deployment makes "Rolling Updates" easier and also signals users that there is no "leader election" logic and each pod can just be "destroyed" at anytime without causing interruption.

Hence I think we should be able to switch from a statefulset to a deployment, even in the single-replica case.

This change also brought up a templating/linting issue: the definition of `.Values.gitea.config.server.SSH_LISTEN_PORT` in `ssh-svc.yaml` just "luckily" worked so far due to naming-related lint processing. Due to the change from "statefulset" to "deployment", the processing queue changed and caused a failure complaining about `config.server.SSH_LISTEN_PORT` not being defined yet.
The only way I could see to fix this was to "properly" define the value in `values.yaml` instead of conditionally definining it in `helpers.tpl`. Maybe there's a better way?

## Chart PVC Creation

I've adapted the automated PVC creation from another chart to be able to provide the `storageClassName` as I couldn't get dynamic provisioning for EFS going with the current implementation.
In addition the naming and approach within the Gitea chart for PV creation is a bit unusual and aligning it might be beneficial.

A semi-unrelated change which will result in a breaking change for existing users but this PR includes a lot of breaking changes already, so including another one might not make it much worse...

- New `persistence.mount`: whether to mount an existing PVC (via `persistence.existingClaim`
- New `persistence.create`: whether to create a new PVC

## Testing

As this PR does a lot of things, we need proper testing.
The helm chart can be installed from the Git branch via `helm-git` as follows:

```
helm repo add gitea-charts git+https://gitea.com/gitea/helm-chart@/?ref=deployment
helm install gitea --version 0.0.0
```
It is **highly recommended** to test the chart in a dedicated namespace.

I've tested this myself with both `redis` and `redis-cluster` and it seemed to work fine.
I just did some basic operations though and we should do more niche testing before merging.

Examplary `values.yml` for testing (only needs a valid RWX storage class):

<details>

<summary>values.yaml</summary>

```yml
image:
  tag: "dev"
  PullPolicy: "Always"
  rootless: true

replicaCount: 2

persistence:
  enabled: true
  accessModes:
    - ReadWriteMany
  storageClass: FIXME

redis-cluster:
  enabled: false
  global:
    redis:
      password: gitea

gitea:
  config:
    indexer:
      ISSUE_INDEXER_ENABLED: true
      REPO_INDEXER_ENABLED: false
```
</details>

## Preferred setup

The preferred HA setup with respect to performance and stability might currently be as follows:

- Repos: RWX (e.g. EFS or Azurefiles NFS)
- Issue indexer: Meilisearch (HA)
- Session and cache: Redis Cluster (HA)
- Attachments/Avatars: Minio (HA)

This will result in a ~ 10-pod HA setup overall.
All pods have very low resource requests.

fix #98

Co-authored-by: pat-s <pat-s@noreply.gitea.io>
Reviewed-on: https://gitea.com/gitea/helm-chart/pulls/437
Co-authored-by: pat-s <patrick.schratz@gmail.com>
Co-committed-by: pat-s <patrick.schratz@gmail.com>
2023-07-17 19:09:42 +00:00
..