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The Envoy process, the data path component of Contour, at times needs to be re-deployed. This could be due to an upgrade, a change in configuration, or a node-failure forcing a redeployment.
When implementing this roll out, the following steps should be taken:
POST
request to /healthcheck/fail
endpointSIGTERM
the podContour implements a new envoy
sub-command which has a shutdown-manager
whose job is to manage a single Envoy instances lifecycle for Kubernetes.
The shutdown-manager
runs as a new container alongside the Envoy container in the same pod.
It exposes two HTTP endpoints which are used for livenessProbe
as well as to handle the Kubernetes preStop
event hook.
/healthz
fail, the container will be restarted./shutdown
endpoint blocks until the connections are drained. - name: shutdown-manager
command:
- /bin/contour
args:
- envoy
- shutdown-manager
image: docker.io/projectcontour/contour:main
imagePullPolicy: Always
lifecycle:
preStop:
httpGet:
path: /shutdown
port: 8090
scheme: HTTP
livenessProbe:
httpGet:
path: /healthz
port: 8090
initialDelaySeconds: 3
periodSeconds: 10
The Envoy container also has some configuration to implement the shutdown manager.
First the preStop
hook is configured to use the /shutdown
endpoint which blocks the container from exiting.
Finally, the pod’s terminationGracePeriodSeconds
is customized to extend the time in which Kubernetes will allow the pod to be in the Terminating
state.
The termination grace period defines an upper bound for long-lived sessions.
If during shutdown, the connections aren’t drained to the configured amount, the terminationGracePeriodSeconds
will send a SIGTERM
to the pod killing it.
The shutdown manager has a set of arguments that can be passed to change how it behaves:
Read our getting started documentation.