Cloud Platform

Metrics

Unikraft Cloud exposes runtime metrics for each instance: CPU time, memory usage, network I/O, connection counts, and scale-to-zero wakeup latencies.

You can currently only view metrics via the API or unikraft api.

Endpoints

Code
GET  /instances/{uuid}/metrics
GET  /instances/metrics?uuid=<uuid>[,<uuid>…]
POST /instances/metrics  # (UUIDs or names in request body)

With no identifiers, the platform returns metrics for all instances in your account. You can also pass a list of names or UUIDs in the POST body.

Response formats

Set the Accept header to control the response format:

`Accept` header	Format
`application/json`	JSON object with an `instances` array.
Any other value (or omitted)	Prometheus text exposition format.

Response fields

Each entry in the instances array contains the following fields:

Identity

Field	Type	Description
`uuid`	string	Instance UUID.
`name`	string	Instance name.

Lifecycle

Field	Type	Description
`state`	string	Current instance state.
`start_count`	int	Number of times the instance has started.
`restart_count`	int	Number of automatic restarts. Omitted if `0`.
`started_at`	timestamp	Time of last start. Omitted if unset.
`stopped_at`	timestamp	Time of last stop. Omitted if unset.
`uptime_ms`	int64	Current uptime in milliseconds.

Boot timing

Field	Type	Description
`boot_time_us`	int	Time from boot trigger to app entry point, in microseconds. Omitted if `0`.
`net_time_us`	int	Time to set up the network interface, in microseconds. Omitted if `0`.

Resource usage

Field	Type	Description
`rss_bytes`	int64	Resident set size: physical memory in use, in bytes.
`cpu_time_ms`	int64	Total CPU time consumed since last start, in milliseconds.

Network throughput

Field	Type	Description
`rx_bytes`	int64	Bytes received since last start.
`rx_packets`	int64	Packets received since last start.
`tx_bytes`	int64	Bytes transmitted since last start.
`tx_packets`	int64	Packets transmitted since last start.

Connection activity

These fields reflect the view from the Unikraft Cloud load balancer, not the instance itself.

Field	Type	Description
`nconns`	int	Number of active TCP connections.
`nreqs`	int	Number of active HTTP requests (non-zero only for HTTP-mode services).
`nqueued`	int	Number of connections or requests waiting for acceptance.
`ntotal`	int64	Total connections or requests processed since last start.

Wakeup latency histogram

For instances with scale-to-zero enabled, the wakeup_latency field contains a histogram of the time between an incoming connection and the instance resuming execution.

Field	Type	Description
`wakeup_latency`	array	Histogram buckets. Each bucket has `bucket_ms` (upper bound in ms, or `null` for the overflow bucket) and `count` (number of wakeups in that bucket).
`wakeup_latency_sum`	uint64	Sum of all recorded wakeup latencies in milliseconds.

Example


JSON
{
  "status": "success",
  "data": {
    "instances": [
      {
        "status": "success",
        "uuid": "f31c1fa8-6188-4ebe-b6e0-b2de063ad7ea",
        "name": "httpserver-go1.21-wf9iz",
        "state": "standby",
        "start_count": 2,
        "started_at": "2026-06-05T11:44:32Z",
        "stopped_at": "2026-06-05T11:44:36Z",
        "uptime_ms": 8161,
        "boot_time_us": 97308,
        "net_time_us": 102963,
        "rss_bytes": 0,
        "cpu_time_ms": 150,
        "rx_bytes": 2012,
        "rx_packets": 23,
        "tx_bytes": 1196,
        "tx_packets": 11,
        "nconns": 0,
        "nreqs": 0,
        "nqueued": 0,
        "ntotal": 2,
        "wakeup_latency": [
          {
            "bucket_ms": 1,
            "count": 0
          },
          {
            "bucket_ms": 2,
            "count": 0
          },
          {
            "bucket_ms": 4,
            "count": 0
          },
          {
            "bucket_ms": 8,
            "count": 0
          },
          {
            "bucket_ms": 16,
            "count": 0
          },
          {
            "bucket_ms": 32,
            "count": 0
          },
          {
            "bucket_ms": 64,
            "count": 0
          },
          {
            "bucket_ms": 128,
            "count": 1
          },
          {
            "bucket_ms": 256,
            "count": 0
          },
          {
            "bucket_ms": 512,
            "count": 0
          },
          {
            "bucket_ms": 1024,
            "count": 0
          },
          {
            "bucket_ms": 2048,
            "count": 0
          },
          {
            "bucket_ms": 4096,
            "count": 0
          },
          {
            "bucket_ms": null,
            "count": 0
          }
        ],
        "wakeup_latency_sum": 104
      }
    ]
  }
}

Learn more

Unikraft Cloud's REST API reference.
Instance states.
Scale-to-zero feature.

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Last modified on July 9, 2026

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