Storage: Unified Storage based on Entity API

[DanCech]

This PR explores running entity api against a separate dedicated database, and the changes needed to support alternative databases beyond sqlite/mysql/postgres.

It requires some configuration to be able to exercise it:

app_mode = development
target = all

[feature_toggles]
unifiedStorage = true
grafanaAPIServer = true
kubernetesPlaylists = true
idForwarding = true

[grafana-apiserver]
storage_type = unified

[entity_api]
db_type = mysql
db_host = localhost:3306
db_name = grafana
db_user = grafanauser
db_pass = grafanapass

With this configuration, you can run everything in-process with:

bra run

The default kubeconfig sends requests directly to the apiserver, to authenticate as a grafana user, create grafana.kubeconfig:

apiVersion: v1
clusters:
- cluster:
    insecure-skip-tls-verify: true
    server: https://127.0.0.1:3000
  name: default-cluster
contexts:
- context:
    cluster: default-cluster
    namespace: default
    user: default
  name: default-context
current-context: default-context
kind: Config
preferences: {}
users:
- name: default
  user:
    username: <username>
    password: <password>

Where <username> and <password> are credentials for basic auth against Grafana.

In this mode, you can interact with the k8s api via:

kubectl --kubeconfig=./grafana.kubeconfig get playlist

To create a playlist, create a file playlist-generate.yaml:

apiVersion: playlist.grafana.app/v0alpha1
kind: Playlist
metadata:
  generateName: x # anything is ok here... except yes or true -- they become boolean!
  labels:
    foo: bar
spec:
  title: Playlist with auto generated UID
  interval: 5m
  items:
  - type: dashboard_by_tag
    value: panel-tests
  - type: dashboard_by_uid
    value: vmie2cmWz # dashboard from devenv

then run:

kubectl --kubeconfig=./grafana.kubeconfig create -f playlist-generate.yaml

To run with a separate storage api using grpc, first update conf/custom.ini and set:

[grafana-apiserver]
storage_type = unified-grpc

Start the storage-apiserver with:

GF_DEFAULT_TARGET=storage-apiserver ./bin/grafana server target

Then in another session start the grafana server:

bra run

Finally, you can list the previously-created playlists with:

kubectl --kubeconfig=./grafana.kubeconfig get playlist

[ryantxu]

@toddtreece @grafana/grafana-app-platform-squad -- this changes the behavior for when we auto-start the extra kubectl port.

This now requires a feature flag (and dev mode) rather than just dev mode. This change was required to simplify the integration test setup, but I think is generally better anyway.

[toddtreece]

the README probably also needs to be updated with this info for kubectl access

[ryantxu]

good call -- updated

[ryantxu]

@DanCech -- i renamed this while we are here futzing with feature flags. In general we will want to clear all reference to "entity" but after merging :)