Add caching support for proxied grafana data sources

[rishabhkailey]

Description

Current Limitation: The project's caching mechanism handles queries to standard data sources via the /api/ds/query endpoint. However, it doesn't extend to proxied data sources, which utilize distinct URLs.

Goal: Expand caching capabilities to encompass proxied data source queries, boosting performance and efficiency for these sources.

[rishabhkailey]

proxied data sources are also using the same endpoint for the query. test setup look like the following

• socks5 proxy with TLS using tlstun

• docker-compose service

  socks5:
  image: tlstun
  entrypoint: ["/tlstun"]
  volumes:
    - ./certs:/certs
  command: ["server", "-addr=:1080", "-ca=/certs/ca.pem", "-cert=/certs/server-cert.pem", "-key=/certs/server-key.pem"]
  

• Grafana config

  GF_SECURE_SOCKS_DATASOURCE_PROXY_ENABLED=true
  GF_SECURE_SOCKS_DATASOURCE_PROXY_SERVER_NAME=socks5
  GF_SECURE_SOCKS_DATASOURCE_PROXY_PROXY_ADDRESS=socks5:1080
  GF_SECURE_SOCKS_DATASOURCE_PROXY_ROOT_CA_CERT=/certs/ca.pem
  GF_SECURE_SOCKS_DATASOURCE_PROXY_CLIENT_KEY=/certs/client-key.pem
  GF_SECURE_SOCKS_DATASOURCE_PROXY_CLIENT_CERT=/certs/client-cert.pem

• data source yaml

  name: prometheus-proxied
  type: prometheus
  access: proxy
  orgId: 1
  url: http://prometheus:9090
  basicAuth: false
  isDefault: false
  version: 1
  editable: true
  uid: prometheus-proxied
  jsonData:
  enableSecureSocksProxy: true
  secureSocksProxyUsername: $PROXY_USER
  secureJsonData:
  secureSocksProxyPassword: $PROXY_PASSWORD

setting incorrect socks proxy leads to an error that means grafana is using socks proxy. but still the query endpoint is same as normal data sources query request.

/api/ds/query?ds_type=prometheus&requestId=Q104

{
  "queries": [
    {
      "datasource": {
        "type": "prometheus",
        "uid": "prometheus-proxied"
      },
      "editorMode": "code",
      "expr": "irate(prometheus_http_request_duration_seconds_sum[1m]) / prometheus_http_request_duration_seconds_count",
      "instant": false,
      "legendFormat": "{{ handler }}",
      "range": true,
      "refId": "A",
      "exemplar": false,
      "requestId": "3A",
      "utcOffsetSec": 19800,
      "interval": "",
      "datasourceId": 1,
      "intervalMs": 20000,
      "maxDataPoints": 1001
    }
  ],
  "from": "1705126273740",
  "to": "1705147873740"
}

I'm not sure when Grafana uses data source proxy API.

this Grafana dashboard uses graphite and proxy data source API.

[rishabhkailey]

moving this issue out of POC & Essential Features milestone.