Add Helm template storage backend logic

[mszostok]

Description

Changes proposed in this pull request:

• Add Helm template storage backend logic

Testing

1. Create cluster:

   export DISABLE_MONITORING_INSTALLATION=true
   export ENABLE_POPULATOR=true
   export CLUSTER_TYPE=k3d
   export DISABLE_K3D_REGISTRY=false
   make dev-cluster
   

2. Install Helm backend via UI
3. Upgrade Helm backend release (new chart is not yet released):

   helm upgrade helm-storage-backend-1648070484 -n default ./deploy/kubernetes/charts/helm-storage-backend --set=global.containerRegistry.path="ghcr.io/capactio/pr" --set=global.containerRegistry.overrideTag="PR-685" --wait --reuse-values

   Update helm release name.
4. Until Handle multiple backends for the TypeInstance #657 is not merge, run:

   kubectl set image deploy/capact-hub-local hub-local=ghcr.io/capactio/pr/hub-js:PR-657
   

5. Install sample Helm release via Runner:

   RUNNER_CONTEXT_PATH=cmd/helm-runner/example-input/context.yaml \
    RUNNER_ARGS_PATH=cmd/helm-runner/example-input/install-args.yaml \
    RUNNER_LOGGER_DEV_MODE=true \
    RUNNER_COMMAND="install" \
    go run cmd/helm-runner/main.go

6. Get ID of cap.type.helm.template.storage:0.1.0
7. Run test:

   BACKEND_ID="ecdfece6-da75-483f-a3ca-24246ed3308d" go test ./pkg/hub/client/ -run TestThatShowcaseExternalStorage -v -count 1

Unfortunately, in my case, it's quite slow. Probably we will need to debug it further. Currently, for my setup to work properly, it requires 1CPU.

The general problem is that the PostgreSQL has as a dependency “common” chart (small size). We need to download it (in general deps charts) as it won't be available by default. The LocateChart method from Helm project, that is able to download this chart, starts with downloading an index file which in case of Bitnami has >3MB. This needs to be decoded and as a result it requires a much higher CPU limit.

You could say, that this is a special case, but unfortunately the PostgreSQL is quite often used in our examples. It needs to work properly.

Additionally, Helm methods don't support context, so we are not able to cancel any ongoing operation even if user cancelled the request and no one will wait for the response.

Related issue(s)

Fix #672

[pkosiec]

Works well, I've just tested that E2E on my PR (capactio/hub-manifests#64). Just a few minor comments 🙂