---
name: prometheus-configuration
description: "Complete guide to Prometheus setup, metric collection, scrape configuration, and recording rules."
risk: critical
source: community
date_added: "2026-02-27"
---
## Supporting material availability

This catalog copy contains the inline guidance below, but does not include the following supporting paths. They are external prerequisites, not bundled files:

- `<support-root>/assets/prometheus.yml.template`
- `<support-root>/references/scrape-configs.md`
- `<support-root>/references/recording-rules.md`
- `<support-root>/scripts/validate-prometheus.sh`

Ask for the original supporting material or an existing installation before using a step that depends on these paths; this catalog does not identify a verified download source for them. Resolve each path relative to that installation, inspect its contents, and verify any applicable license and execution prerequisites. Do not run a command or claim a referenced procedure was followed until its required file exists. Do not fabricate the missing scripts or treat an unrelated file with the same name as equivalent. Independent steps fully documented here can proceed within the user’s authorized scope; report any dependent step as unavailable.


# Prometheus Configuration

Complete guide to Prometheus setup, metric collection, scrape configuration, and recording rules.

## Do not use this skill when

- The task is unrelated to prometheus configuration
- You need a different domain or tool outside this scope

## Instructions

- Clarify goals, constraints, and required inputs.
- Apply relevant best practices and validate outcomes.
- Provide actionable steps and verification.

## Purpose

Configure Prometheus for comprehensive metric collection, alerting, and monitoring of infrastructure and applications.

## Use this skill when

- Set up Prometheus monitoring
- Configure metric scraping
- Create recording rules
- Design alert rules
- Implement service discovery

## Prometheus Architecture

```
┌──────────────┐
│ Applications │ ← Instrumented with client libraries
└──────┬───────┘
       │ /metrics endpoint
       ↓
┌──────────────┐
│  Prometheus  │ ← Scrapes metrics periodically
│    Server    │
└──────┬───────┘
       │
       ├─→ AlertManager (alerts)
       ├─→ Grafana (visualization)
       └─→ Long-term storage (Thanos/Cortex)
```

## Installation

### Kubernetes with Helm

```bash
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm repo update

helm install prometheus prometheus-community/kube-prometheus-stack \
  --namespace monitoring \
  --create-namespace \
  --set prometheus.prometheusSpec.retention=30d \
  --set prometheus.prometheusSpec.storageVolumeSize=50Gi
```

### Docker Compose

```yaml
version: '3.8'
services:
  prometheus:
    image: prom/prometheus:latest
    ports:
      - "9090:9090"
    volumes:
      - ./prometheus.yml:/etc/prometheus/prometheus.yml
      - prometheus-data:/prometheus
    command:
      - '--config.file=/etc/prometheus/prometheus.yml'
      - '--storage.tsdb.path=/prometheus'
      - '--storage.tsdb.retention.time=30d'

volumes:
  prometheus-data:
```

## Configuration File

**prometheus.yml:**
```yaml
global:
  scrape_interval: 15s
  evaluation_interval: 15s
  external_labels:
    cluster: 'production'
    region: 'us-west-2'

# Alertmanager configuration
alerting:
  alertmanagers:
    - static_configs:
        - targets:
          - alertmanager:9093

# Load rules files
rule_files:
  - /etc/prometheus/rules/*.yml

# Scrape configurations
scrape_configs:
  # Prometheus itself
  - job_name: 'prometheus'
    static_configs:
      - targets: ['localhost:9090']

  # Node exporters
  - job_name: 'node-exporter'
    static_configs:
      - targets:
        - 'node1:9100'
        - 'node2:9100'
        - 'node3:9100'
    relabel_configs:
      - source_labels: [__address__]
        target_label: instance
        regex: '([^:]+)(:[0-9]+)?'
        replacement: '${1}'

  # Kubernetes pods with annotations
  - job_name: 'kubernetes-pods'
    kubernetes_sd_configs:
      - role: pod
    relabel_configs:
      - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scrape]
        action: keep
        regex: true
      - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_path]
        action: replace
        target_label: __metrics_path__
        regex: (.+)
      - source_labels: [__address__, __meta_kubernetes_pod_annotation_prometheus_io_port]
        action: replace
        regex: ([^:]+)(?::\d+)?;(\d+)
        replacement: $1:$2
        target_label: __address__
      - source_labels: [__meta_kubernetes_namespace]
        action: replace
        target_label: namespace
      - source_labels: [__meta_kubernetes_pod_name]
        action: replace
        target_label: pod

  # Application metrics
  - job_name: 'my-app'
    static_configs:
      - targets:
        - 'app1.example.com:9090'
        - 'app2.example.com:9090'
    metrics_path: '/metrics'
    scheme: 'https'
    tls_config:
      ca_file: /etc/prometheus/ca.crt
      cert_file: /etc/prometheus/client.crt
      key_file: /etc/prometheus/client.key
```

**Reference:** See `assets/prometheus.yml.template`

## Scrape Configurations

### Static Targets

```yaml
scrape_configs:
  - job_name: 'static-targets'
    static_configs:
      - targets: ['host1:9100', 'host2:9100']
        labels:
          env: 'production'
          region: 'us-west-2'
```

### File-based Service Discovery

```yaml
scrape_configs:
  - job_name: 'file-sd'
    file_sd_configs:
      - files:
        - /etc/prometheus/targets/*.json
        - /etc/prometheus/targets/*.yml
        refresh_interval: 5m
```

**targets/production.json:**
```json
[
  {
    "targets": ["app1:9090", "app2:9090"],
    "labels": {
      "env": "production",
      "service": "api"
    }
  }
]
```

### Kubernetes Service Discovery

```yaml
scrape_configs:
  - job_name: 'kubernetes-services'
    kubernetes_sd_configs:
      - role: service
    relabel_configs:
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scrape]
        action: keep
        regex: true
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_scheme]
        action: replace
        target_label: __scheme__
        regex: (https?)
      - source_labels: [__meta_kubernetes_service_annotation_prometheus_io_path]
        action: replace
        target_label: __metrics_path__
        regex: (.+)
```

**Reference:** See `references/scrape-configs.md`

## Recording Rules

Create pre-computed metrics for frequently queried expressions:

```yaml
# /etc/prometheus/rules/recording_rules.yml
groups:
  - name: api_metrics
    interval: 15s
    rules:
      # HTTP request rate per service
      - record: job:http_requests:rate5m
        expr: sum by (job) (rate(http_requests_total[5m]))

      # Error rate percentage
      - record: job:http_requests_errors:rate5m
        expr: sum by (job) (rate(http_requests_total{status=~"5.."}[5m]))

      - record: job:http_requests_error_rate:percentage
        expr: |
          (job:http_requests_errors:rate5m / job:http_requests:rate5m) * 100

      # P95 latency
      - record: job:http_request_duration:p95
        expr: |
          histogram_quantile(0.95,
            sum by (job, le) (rate(http_request_duration_seconds_bucket[5m]))
          )

  - name: resource_metrics
    interval: 30s
    rules:
      # CPU utilization percentage
      - record: instance:node_cpu:utilization
        expr: |
          100 - (avg by (instance) (rate(node_cpu_seconds_total{mode="idle"}[5m])) * 100)

      # Memory utilization percentage
      - record: instance:node_memory:utilization
        expr: |
          100 - ((node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes) * 100)

      # Disk usage percentage
      - record: instance:node_disk:utilization
        expr: |
          100 - ((node_filesystem_avail_bytes / node_filesystem_size_bytes) * 100)
```

**Reference:** See `references/recording-rules.md`

## Alert Rules

```yaml
# /etc/prometheus/rules/alert_rules.yml
groups:
  - name: availability
    interval: 30s
    rules:
      - alert: ServiceDown
        expr: up{job="my-app"} == 0
        for: 1m
        labels:
          severity: critical
        annotations:
          summary: "Service {{ $labels.instance }} is down"
          description: "{{ $labels.job }} has been down for more than 1 minute"

      - alert: HighErrorRate
        expr: job:http_requests_error_rate:percentage > 5
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High error rate for {{ $labels.job }}"
          description: "Error rate is {{ $value }}% (threshold: 5%)"

      - alert: HighLatency
        expr: job:http_request_duration:p95 > 1
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High latency for {{ $labels.job }}"
          description: "P95 latency is {{ $value }}s (threshold: 1s)"

  - name: resources
    interval: 1m
    rules:
      - alert: HighCPUUsage
        expr: instance:node_cpu:utilization > 80
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High CPU usage on {{ $labels.instance }}"
          description: "CPU usage is {{ $value }}%"

      - alert: HighMemoryUsage
        expr: instance:node_memory:utilization > 85
        for: 5m
        labels:
          severity: warning
        annotations:
          summary: "High memory usage on {{ $labels.instance }}"
          description: "Memory usage is {{ $value }}%"

      - alert: DiskSpaceLow
        expr: instance:node_disk:utilization > 90
        for: 5m
        labels:
          severity: critical
        annotations:
          summary: "Low disk space on {{ $labels.instance }}"
          description: "Disk usage is {{ $value }}%"
```

## Validation

```bash
# Validate configuration
promtool check config prometheus.yml

# Validate rules
promtool check rules /etc/prometheus/rules/*.yml

# Test query
promtool query instant http://localhost:9090 'up'
```

**Reference:** See `scripts/validate-prometheus.sh`

## Best Practices

1. **Use consistent naming** for metrics (prefix_name_unit)
2. **Set appropriate scrape intervals** (15-60s typical)
3. **Use recording rules** for expensive queries
4. **Implement high availability** (multiple Prometheus instances)
5. **Configure retention** based on storage capacity
6. **Use relabeling** for metric cleanup
7. **Monitor Prometheus itself**
8. **Implement federation** for large deployments
9. **Use Thanos/Cortex** for long-term storage
10. **Document custom metrics**

## Troubleshooting

**Check scrape targets:**
```bash
curl http://localhost:9090/api/v1/targets
```

**Check configuration:**
```bash
curl http://localhost:9090/api/v1/status/config
```

**Test query:**
```bash
curl 'http://localhost:9090/api/v1/query?query=up'
```

## Reference Files

- `assets/prometheus.yml.template` - Complete configuration template
- `references/scrape-configs.md` - Scrape configuration patterns
- `references/recording-rules.md` - Recording rule examples
- `scripts/validate-prometheus.sh` - Validation script

## Related Skills

- `grafana-dashboards` - For visualization
- `slo-implementation` - For SLO monitoring
- `distributed-tracing` - For request tracing

## Limitations
- Use this skill only when the task clearly matches the scope described above.
- Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
- Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.