CoreDNS

Monitor CoreDNS — DNS request rates, response codes, cache hit rates, and plugin latencies — using CoreDNS's built-in Prometheus plugin.

Pattern: CoreDNS prometheus plugin → Prometheus scrape → xScaler remote_write

---

Prerequisites

• CoreDNS 1.6+
• xScaler tenant credentials (token + tenant ID)

---

Enable Metrics

Add the prometheus directive to your Corefile:

. {
  prometheus :9153
  forward . 8.8.8.8
  cache 30
  log
}

Verify:

curl -s http://localhost:9153/metrics | grep coredns_dns_requests_total

---

Option A — Prometheus

scrape_configs:
  - job_name: coredns
    static_configs:
      - targets: ['localhost:9153']

remote_write:
  - url: https://euw1-01.m.xscalerlabs.com/api/v1/push
    authorization:
      credentials: <token>
    headers:
      X-Scope-OrgID: <tenant-id>

---

Option B — Grafana Alloy

prometheus.scrape "coredns" {
  targets    = [{"__address__" = "localhost:9153"}]
  forward_to = [prometheus.remote_write.xscaler.receiver]
}

prometheus.remote_write "xscaler" {
  endpoint {
    url = "https://euw1-01.m.xscalerlabs.com/api/v1/push"
    authorization {
      type        = "Bearer"
      credentials = "<token>"
    }
    headers = { "X-Scope-OrgID" = "<tenant-id>" }
  }
}

---

Option C — OpenTelemetry Collector

receivers:
  prometheus:
    config:
      scrape_configs:
        - job_name: coredns
          static_configs:
            - targets: ['localhost:9153']

processors:
  batch:
    timeout: 10s

exporters:
  otlphttp/xscaler:
    endpoint: https://euw1-01.m.xscalerlabs.com
    headers:
      Authorization: "Bearer <token>"
      X-Scope-OrgID: "<tenant-id>"
    compression: gzip

service:
  pipelines:
    metrics:
      receivers:  [prometheus]
      processors: [batch]
      exporters:  [otlphttp/xscaler]

---

Logs

Collect CoreDNS query log and error log from the container. Add the following to your Alloy config:

discovery.docker "coredns_containers" {
  host = "unix:///var/run/docker.sock"
  filter {
    name   = "name"
    values = ["coredns"]
  }
}

discovery.relabel "coredns_logs" {
  targets = discovery.docker.coredns_containers.targets
  rule {
    source_labels = ["__meta_docker_container_name"]
    regex         = "/(.*)"
    target_label  = "container"
  }
  rule {
    replacement  = "integrations/coredns"
    target_label = "job"
  }
}

loki.source.docker "coredns_logs" {
  host       = "unix:///var/run/docker.sock"
  targets    = discovery.relabel.coredns_logs.output
  forward_to = [loki.write.xscaler.receiver]
  labels     = { instance = constants.hostname }
}

loki.write "xscaler" {
  endpoint {
    url = "https://euw1-01.l.xscalerlabs.com/api/v1/logs/push"

    http_client_config {
      authorization {
        type        = "Bearer"
        credentials = env("XSCALER_TOKEN")
      }
    }

    headers = { "X-Scope-OrgID" = env("XSCALER_TENANT_ID") }
  }
}

Key metrics

Metric	Description
coredns_dns_requests_total	Total DNS requests by type and zone
coredns_dns_responses_total	Total responses by rcode
coredns_cache_hits_total	Cache hits
coredns_cache_misses_total	Cache misses
coredns_dns_request_duration_seconds	Request duration histogram
coredns_forward_requests_total	Requests forwarded upstream
coredns_forward_request_duration_seconds	Upstream forward latency