Implement add profile to install a profile to a cluster

[nikimanoledaki]

Closes: #1109

What changed? Why?
This PR adds the ability to install a profile to a cluster.

Usage

Minimum/required flags:
gitops add profile --name=podinfo --cluster=prod --config-repo=ssh://git@github.com/owner/config-repo.git

Optional flags:

• --namespace defaults to wego-system
• --version defaults to latest
• --port for the Profiles API port
• --auto-merge
• --kubeconfig

Implementation Notes

1. The HelmRepository Flux resource that contains the Chart must already be present and available for installation in the cluster.
2. add profile discovers the HelmRepository's name and namespace through a Get query to the Profiles API. While this PR tries to rely on the Git provider API to use the .weave-gitops directory as the Source of Truth, add profile defers to get profiles to discover the HelmRepository's name and namespace, and its workflow still requires access to the cluster through a local kubeconfig. However, this will become optional as part of the following ticket: Add support for installing a profile without requiring kubeconfig access #1371
3. add profile creates a HelmRelease that references the HelmRepository name and namespace.

apiVersion: helm.toolkit.fluxcd.io/v2beta1
kind: HelmRelease
metadata:
  name: nginx
  namespace: wego-system
spec:
  releaseName: nginx
  chart: 
    spec:
      chart: nginx
      sourceRef:
        kind: HelmRepository
        name: // discovered by Get Profiles
        namespace: wego-system // discovered by Get Profiles
      Version: 0.0.1
  interval: 1m
status: {}

4. If no other HelmRelease exists with the same name/version/namespace/cluster combination in the config repository's Profiles manifest located at /.weave-gitops/clusters/<cluster name>/system/profiles.yaml, add profile appends the new HelmRelease to it. Otherwise, it returns an error.

.weave-gitops
└── clusters
    	└── prod
    		└── system
        		└── profiles.yaml // kind: HelmRelease

5. Flux watches the profile.yaml file for new HelmReleases and installs them.

GitProvider interface additions

• This PR implements gitprovider.GetRepoFiles to fetch a repo's subdirectory and its files. It's essentially a wrapper around go-git-providers to use .Files().Get(ctx, path, branch). add profile uses this func to get the /weave-gitops/clusters/<cluster-name>/system/profiles.yaml file from the config repo to read/append HelmReleases to it.

• This PR also implements gitprovider.MergePullRequest to merge a PR through the Git provider API without relying on a local clone of the config repo. auto-merge in the acceptance tests uses this function.

How did you test it?

Manual Test

// Create cluster
kind create cluster --name test-01

// Edit `manifests/wego-app/deployment.yaml` to point to own container registry & build/push image
docker build -t niki2401/wego-app:latest -f Dockerfile . && docker push niki2401/wego-app:latest

// Make binary
make bin

// Install gitops
./bin/gitops install --config-repo ssh://git@github.com/nikimanoledaki/fun-times.git --auto-merge

// Create helmrepository 
touch helmrepo.yaml
cat <<EOF >./helmrepo.yaml 
apiVersion: source.toolkit.fluxcd.io/v1beta1
kind: HelmRepository
metadata:
  name: weaveworks-charts
  namespace: wego-system
spec:
  interval: 1m0s
  timeout: 1m0s
  url: https://weaveworks.github.io/profiles-examples
EOF
k apply -f helmrepo.yaml 

// Port-forward wego-app API
k port-forward pod/wego-app-<generated name> 9001 9001 -n wego-system

// Install Profile
./bin/gitops add profile --name podinfo --config-repo ssh://git@github.com/nikimanoledaki/fun-times.git --cluster kind-test-01 --version 6.0.0 --auto-merge
► getting available profiles in kind-test-01/wego-system
► Pull Request created: https://github.com/nikimanoledaki/fun-times/pull/29
► auto-merge=true; merging PR number 29
Adding profile:

Name: podinfo
Version: 6.0.0
Cluster: kind-test-01
Namespace: wego-system

// check profile is running
k get pods -A
wego-system          pod/kind-test-01-podinfo-569494d49d-xch8m           1/1     Running   0          30s

Acceptance Test

• Example PR + changes created in a config repo by the acceptance test: https://github.com/weaveworks-gitops-test/test-app-o1yvvchf

Release notes

Documentation Changes
Not sure where to add docs for this? 🤔

[aclevername]

do we want the alias since you can only install 1 at a time?

[Himangini]

CC @davidstauffer @sympatheticmoose

[bigkevmcd]

This sets up an unfortunate error pattern, where you run it and it tells you something is invalid, so you fix it, and then you run it again, and it tells you something else is invalid.

Maybe a multierror would be better?

At least, return a slice of strings with all the errors.

[Skarlso]

Isn't the problem that these depend on each other? If opts.Name is not defined, you can't call ApplicationNameTooLong. And then you can't call HasPrefix either. Though I agree that ConfigRepo and Cluster could be checked separately.

[nikimanoledaki]

Changed this in the commit that addresses review feedback - the validateAddOptions func only has 2 checks in it now since I moved the required flags to Cobra's feature for checking for required flags.

[nikimanoledaki]

Hey folks 👋 @aclevername @Skarlso @cPu1 @Himangini @bigkevmcd @jpellizzari

Thank you all for the reviews! I've responded to and/or addressed all feedback. I didn't want to spam everyone by responding with Done! 50 times so I marked each comment that was addressed and completed with a "👍". The commit that addresses all review feedback (not linking it since it'll change anyway) also contains a list of all the requested changes for this round of reviews. :)

Feel free to mark any leftover comment as resolved and/or review and comment more!

PS: integration tests + linter currently pass ✅

[Himangini]

Well done Niki 👏🏻 , I have gone through all the files and have a few minor comments, otherwise the PR looks pretty good to me 🎉

[Himangini]

For Documentation, adding something under https://docs.gitops.weave.works/docs/cluster-management/profiles section should be sufficient I think. cc @sympatheticmoose @josefaworks wdyt?

[Skarlso]

LGTM with that one last break addition. :) And Kevin's comment about the possible too long name.

[Himangini]

🎉 👍🏻