Prometheus scraping

Prometheus scraping

Radiator exposes operational counters, timing aggregations and info gauges over authenticated HTTP management endpoints over Prometheus 0.0.4. Metrics are held in memory; reads are inexpensive and non‑blocking. This means they reset at restart.

Access control & authentication

Scraping requires an HTTP management user with at least monitor privilege. Define this in the management.http.credentials block:

credentials {
    user "monitor" {
        password "monitorpassword";
        privilege monitor;
    }
}

Use HTTP Basic Auth when scraping:

curl -u monitor:monitorpassword --basic \
  http://localhost:8080/api/v1/metrics/prometheus

Example Prometheus configuration

Prometheus server configuration prometheus.yml snippet example:

scrape_configs:
  - job_name: "radiator-server"
    metrics_path: "/api/v1/metrics/prometheus"
    basic_auth:
      username: "monitor"
      password: "monitorpassword"
    static_configs:
      - targets: ["127.0.0.1:8080"]

Example scrape output (excerpt)

From an integration test run showing log-based counters after authentication attempts:

# TYPE radiator_build_info gauge
radiator_build_info{app="radiator",version="10.31.0",kind="development",timestamp="2025-12-12T06:00:47Z",cpu_target="aarch64-apple-darwin",branch="main",commit="abc123"} 1
# TYPE radiator_uptime_seconds gauge
radiator_uptime_seconds{service_ok="true"} 3600
# TYPE radiator_instance_info gauge
radiator_instance_info{instance_id="R01",pid="12345"} 1
# TYPE radiator_log_total counter
radiator_log_total{namespace="RADIUS UDP::AUTH_UDP",message="Radius UDP packet from unknown client"} 5
radiator_log_total{namespace="policy::BASIC_AUTH::handler::PAP",message="AAA accept"} 999
radiator_log_total{namespace="policy::BASIC_AUTH::handler::PAP::backend call::USERS_FILE",message="Backend query accepted"} 999
# TYPE radiator_total counter
radiator_total{namespace="policy::BASIC_AUTH"} 1500
...

Key metrics:

Build and Instance Information

• radiator_build_info: build metadata gauge with labels for version, branch, commit, etc.
• radiator_uptime_seconds: time since server started.
• radiator_instance_info: instance identification with instance_id, optional cluster_id, and process ID.

Process Statistics

• radiator_process_memory_rss_bytes: resident set size (RSS) memory usage in bytes.
• radiator_process_cpu_milliseconds_total: total CPU time used by the process in milliseconds.

System Statistics

• radiator_system_memory_total_bytes: total system memory in bytes.
• radiator_system_memory_available_bytes: available system memory in bytes (Linux only).
• radiator_system_swap_total_bytes: total swap space in bytes (Linux only).
• radiator_system_swap_used_bytes: used swap space in bytes (Linux only).
• radiator_system_swap_pages_in_total: total pages swapped in from disk (Linux only).
• radiator_system_swap_pages_out_total: total pages swapped out to disk (Linux only).
• radiator_system_cpu_count: number of CPUs available.
• radiator_system_cpu_active_milliseconds_total: total active (non-idle) CPU time across all CPUs in milliseconds (Linux only).
• radiator_system_cpu_total_milliseconds_total: total CPU time across all CPUs in milliseconds (Linux only).
• radiator_system_load_1m_x100: 1-minute load average multiplied by 100.
• radiator_system_load_5m_x100: 5-minute load average multiplied by 100.
• radiator_system_load_15m_x100: 15-minute load average multiplied by 100.

Log Counters

• radiator_log_total: log message counters with hierarchical namespace (using :: separator) and message labels. The namespace represents the logging context hierarchy (e.g., server, policy, handler, backend).
• radiator_total: aggregate counters per namespace prefix.

Note: System statistics are OS dependent.

High availability labels

See the high availability identifiers article for semantics of instance / cluster IDs. The radiator_instance_info gauge includes instance_id.

Usage guidelines

• Most metrics are in memory information. Some OS level information will require system calls which has a small performance impact. In general polling once a second should not have an impact.
• Do not expose metrics endpoints without authentication; they reveal operational structure.

Troubleshooting

Push gateway (optional)

prompush is verified to work against Radiator for cases where Prometheus cannot directly scrape Radiator instances.