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Health checks in the Apollo Router

Determining the router's status

Health checks are often used by load balancers to determine whether a server is available and ready to start serving traffic.

The Apollo supports a basic HTTP-level health check. This is enabled by default and is served on port 8088 at the URL path /health. This returns a 200 status code if the HTTP server is successfully serving. You can change this by setting health_check:

enabled: true

Testing with curl

The following example demonstrates using the curl command to send a basic health check query to an Apollo instance running at

$ curl -v ""
* Trying
* Connected to ( port 8088 (#0)
> GET /health HTTP/1.1
> Host:
> User-Agent: curl/7.79.1
> Accept: */*
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< vary: origin
< content-type: application/json
< content-length: 15
< date: Wed, 21 Sep 2022 17:10:45 GMT
* Connection #0 to host left intact


If you start the with trace logging enabled, you will see a log from the router for each health check:

--log apollo_router=trace
2023-01-23T17:42:04.640501Z apollo-router/src/axum_factory/ TRACE apollo_router::axum_factory::axum_http_server_factory: health check health=Health { status: Up } request=Request { method: GET, uri: /health, version: HTTP/1.1, headers: {"host": "", "user-agent": "curl/7.85.0", "accept": "*/*"}, body: Body(Empty) }

This may be helpful with confirming that health-checks are working correctly.

Using in a containers environment

The health check listens to by default, which won't allow connections issued from a network. While this is a safe default, other containers won't be able to perform health checks, which will prevent the pod from switching to a healthy state.

You can change this by setting health_check:

enabled: true

Using with Kubernetes

In Kubernetes, you can configure health checks by setting readinessProbe and livenessProbe on the containers object of the resource definition:

# ... snipped for partial example ...
- name: router
# ... snipped for partial example ...
path: "/health"
port: 8088
path: "/health"
port: 8088
# ... snipped for partial example ...

See a more complete example in our Kubernetes documentation.

Using with Docker

Docker has a HEALTHCHECK instruction that tells Docker how to test whether a container is still working. These are defined in the Dockerfile when building your container:

HEALTHCHECK CMD curl --fail \
"" || exit 1

We don't define these in our example Dockerfiles, because they aren't commonly used. You can add them to your own images as needed.

Client awareness
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