grpc_health_probe(1)
The grpc_health_probe utility allows you to query health of gRPC services that
expose service their status through the gRPC Health Checking Protocol.
This command-line utility makes a RPC to /grpc.health.v1.Health/Check. If it
responds with a SERVING status, the grpc_health_probe will exit with
success, otherwise it will exit with a non-zero exit code (documented below).
grpc_health_probe is meant to be used for health checking gRPC applications in
Kubernetes, using the exec probes.
EXAMPLES
$ grpc_health_probe -addr=localhost:5000
healthy: SERVING
$ grpc_health_probe -addr=localhost:9999 -connect-timeout 250ms -rpc-timeout 100ms
failed to connect service at "localhost:9999": context deadline exceeded
exit status 2
Installation
It is recommended to use a version-stamped binary distribution:
- Refer to the Releases section for binary distributions.
Installing from source (not recommended)
- Make sure you have
gitandgoinstalled. - Run:
go get github.com/grpc-ecosystem/grpc-health-probe - This will compile the binary into your
$GOPATH/bin(or$HOME/go/bin).
Using the gRPC Health Checking Protocol
To make use of the grpc_health_probe, your application must implement the
gRPC Health Checking Protocol v1. This means you must to register the
Health service and implement the rpc Check that returns a SERVING status.
Since the Health Checking protocol is part of the gRPC core, it has
packages/libraries available for the languages supported by gRPC:
[health.proto]
[Go]
[Java]
[Python]
[C#/NuGet]
[Ruby] ...
Most of the languages listed above provide helper functions that hides
implementation details. This eliminates the need for you to implement the
Check rpc yourself.
Example: gRPC health checking on Kubernetes
You are recommended to use Kubernetes exec probes and define
liveness and readiness checks for your gRPC server pods.
You can bundle the statically compiled grpc_health_probe in your container
image. Choose a binary release and download it in your Dockerfile:
RUN GRPC_HEALTH_PROBE_VERSION=v0.3.1 && \
wget -qO/bin/grpc_health_probe https://github.com/grpc-ecosystem/grpc-health-probe/releases/download/${GRPC_HEALTH_PROBE_VERSION}/grpc_health_probe-linux-amd64 && \
chmod +x /bin/grpc_health_probe
In your Kubernetes Pod specification manifest, specify a livenessProbe and/or
readinessProbe for the container:
spec:
containers:
- name: server
image: "[YOUR-DOCKER-IMAGE]"
ports:
- containerPort: 5000
readinessProbe:
exec:
command: ["/bin/grpc_health_probe", "-addr=:5000"]
initialDelaySeconds: 5
livenessProbe:
exec:
command: ["/bin/grpc_health_probe", "-addr=:5000"]
initialDelaySeconds: 10
This approach provide proper readiness/liveness checking to your applications
that implement the gRPC Health Checking Protocol.
Health Checking TLS Servers
If a gRPC server is serving traffic over TLS, or uses TLS client authentication
to authorize clients, you can still use grpc_health_probe to check health
with command-line options:, Option, Description, :------------, -------------, -tls, use TLS (default: false), -tls-ca-cert, path to file containing CA certificates (to override system root CAs), -tls-client-cert, client certificate for authenticating to the server, -tls-client-key, private key for for authenticating to the server, -tls-no-verify, use TLS, but do not verify the certificate presented by the server (INSECURE) (default: false), -tls-server-name, override the hostname used to verify the server certificate, Example:
-
Start the
route_guideexample
server
with TLS by running:go run server/server.go -tls -
Run
grpc_client_probewith the CA
certificate
(in thetestdata/directory) and hostname override the
cert is signed for:$ grpc_health_probe -addr 127.0.0.1:10000 \ -tls \ -tls-ca-cert /path/to/testdata/ca.pem \ -tls-server-name=x.test.youtube.com status: SERVING
Exit codes
It is not recommended to rely on specific exit statuses. Any failure will be
a non-zero exit code., Exit Code, Description, :-----------:, -------------, 0, success: rpc response is SERVING., 1, failure: invalid command-line arguments, 2, failure: connection failed or timed out, 3, failure: rpc failed or timed out, 4, failure: rpc successful, but the response is not SERVING, ----
This is not an official Google project.