COREDNS-HEALTH(7)

💖 NAME 💖

okay so this is COREDNS-HEALTH(7) from the CoreDNS Plugins collection, and the plugin is health — it enables a health check endpoint. that’s the whole vibe, bestie 💅

🌸 DESCRIPTION 🌸

This plugin enables a process-wide health endpoint. When CoreDNS is up and running, it returns a 200 OK HTTP status code. By default, health is exported on 8080/health.

✨ SYNTAX ✨

health [ADDRESS]

It optionally takes an ADDRESS; the default is :8080. The health path is fixed to /health — no custom paths, periodt. The health endpoint returns a 200 response code and the word "OK" when this server is healthy.

An extra option can be set with this extended syntax:

health [ADDRESS] {
    lameduck DURATION
}

• lameduck DURATION — this will delay shutdown for DURATION. /health will still answer 200 OK.

⚠️ Note: The ready plugin will not answer OK while CoreDNS is in lame duck mode prior to shutdown.

If you have multiple Server Blocks, health can only be enabled in one of them (as it is process wide). If you really need multiple endpoints, you must run health endpoints on different ports:

com {
    whoami
    health :8080
}

net {
    erratic
    health :8081
}

Doing this is supported but both endpoints ":8080" and ":8081" will export the exact same health.

🔥 METRICS 🔥

If monitoring is enabled (via the prometheus plugin) then the following metrics are exported:

• coredns_health_request_duration_seconds{} — the health plugin performs a self health check once per second on the /health endpoint. This metric is the duration to process that request. As this is a local operation it should be fast. A (large) increase in this duration indicates the CoreDNS process is having trouble keeping up with its query load.
• coredns_health_request_failures_total{} — the number of times the self health check failed.

💡 Note that these metrics do not have a server label, because being overloaded is a symptom of the running process, not a specific server.

🎀 EXAMPLES 🎀

Run another health endpoint on http://localhost:8091 (the original also shows ⟨http://localhost:8091⟩ — same URL, iykyk).

. {
    health localhost:8091
}

Set a lame duck duration of 1 second:

. {
    health localhost:8092 {
        lameduck 1s
    }
}

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Source/version: CoreDNS — date: March 2026 — manual: COREDNS-HEALTH(7). stay healthy, bestie 💅✨🫶