As a Korifi API user I want to be able to get app/process metrics via the /api/v1/read endpoint

[georgethebeatle]

Background

As of today Korifi implements metrics-fetching by directly querying the custom resources provided by the metrics server.

While this is enough to enable the basic cf push behaviour, it violates one of CF's abstractions that enables logs and metrics to be served by an external component that speaks a well-defined API.

Acceptance

GIVEN I have pushed an app to Korifi
WHEN I run cf curl /api/v1/read/<app-guid>?envelope_types=GAUGE
THEN I get a 403 Forbidden Response

WHEN I am bound to a role that is allowed to read cfapps
WHEN I run cf curl /api/v1/read/<app-guid>?envelope_types=GAUGE
THEN I get a resonse as follows

NOTE: this is the complete envelope as it is returned by classic cf. We should only support the minimal set of fields that enable basic cf commands (cf push, cf app)

"envelopes": {
  "batch": [
    {
      "timestamp": "1737732014790586000",
      "instance_id": "0",
      "deprecated_tags": {},
      "tags": {
        "app_id": "e75acbc9-fb11-4200-800b-bfcec928e758",
        "app_name": "dora",
        "deployment": "cf",
        "index": "41432433-3e0b-401b-a1b6-068708a4688a",
        "instance_id": "0",
        "ip": "10.244.0.139",
        "job": "diego-cell",
        "organization_id": "37707b21-ede7-4940-bb95-5724b714d4ae",
        "organization_name": "org",
        "origin": "rep",
        "process_id": "b7585d8a-ab70-4061-931b-278439a60f13",
        "process_instance_id": "85cb3c9f-87cd-4f2d-420f-ffc9",
        "process_type": "worker",
        "source_id": "e75acbc9-fb11-4200-800b-bfcec928e758",
        "space_id": "6cdfc65b-5b9d-43db-a7ce-2445996b1123",
        "space_name": "space"
      },
      "gauge": {
        "metrics": {
          "log_rate": {
            "unit": "B/s",
            "value": 0
          }
        },{
          "log_rate_limit": {
            "unit": "B/s",
            "value": -1
          }
        },{
          "container_age": {
            "unit": "nanoseconds",
            "value": 204978503253
          }
        },{
          "disk": {
            "unit": "bytes",
            "value": 136507392
          }
        },{
          "memory": {
            "unit": "bytes",
            "value": 47553649
          }
        },{
          "cpu": {
            "unit": "percentage",
            "value": 0.5353665896914775
          }
        },{
          "disk_quota": {
            "unit": "bytes",
            "value": 1073741824
          }
        },{
          "memory_quota": {
            "unit": "bytes",
            "value": 268435456
          }
        }
      }
    },
    ...
  ]
}

WHEN I run cf curl /api/v1/read/<app-guid>?envelope_types=GAUGE&start_time=<timestamp>
THEN I only get envelopes newer than

WHEN I run cf curl /api/v1/read/<app-guid>?envelope_types=GAUGE&limit=1
THEN I only get one envelope

WHEN I run cf curl /api/v1/read/<app-guid>?envelope_types=GAUGE&descending=true
THEN I get a the newest envelopes first

Dev Notes

Log Cache API