This page describes how hook targets are defined in various APIs.

Each hook that you define as part of using one of the hook-based APIs has the following fields:

webhookSpecify how to invoke this hook over HTTP(S).


  url: http://my-controller-svc/sync


Each Webhook has the following fields:

etagA configuration for etag logic
urlA full URL for the webhook (e.g. http://my-controller-svc/hook). If present, this overrides any values provided for path and service.
timeoutA duration (in the format of Go's time.Duration) indicating the time that Metacontroller should wait for a resserviceponse. If the webhook takes longer than this time, the webhook call is aborted and retried later. Defaults to 10s.
pathA path to be appended to the accompanying service to reach this hook (e.g. /hook). Ignored if full url is specified.
serviceA reference to a Kubernetes Service through which this hook can be reached.

Service Reference

Within a webhook, the service field has the following subfields:

nameThe metadata.name of the target Service.
namespaceThe metadata.namespace of the target Service.
portThe port number to connect to on the target Service. Defaults to 80.
protocolThe protocol to use for the target Service. Defaults to http.

Etag Reference

More details in rfc7232.

Etag is a hash of response content, controller that supports etag notion should add "ETag" header to each 200 response. Metacontrollers that support "ETag" should send the "If-None-Match" header with value of ETag of cached content. If content has not changed, controller should reply with "304 Not modified" or "412 Precondition Failed", otherwise it sends 200 with "ETag" header.

This logic helps save traffic and CPU time on webhook processing.

Within a webhook, the eTag field has the following subfields:

Enabled             *bool  `json:"enabled,omitempty"`
CacheTimeoutSeconds *int32 `json:"cacheTimeoutSeconds,omitempty"`
CacheCleanupSeconds *int32 `json:"cacheCleanupSeconds,omitempty"`
Enabledtrue or false. Default is false
CacheTimeoutSecondsTime in seconds after which ETag cache record is forgotten
CacheCleanupSecondsHow often ETag is running garbage collector to cleanup forgotten records