配置逐步向修订版推出流量¶

If your traffic configuration points to a Configuration target instead of a Revision target, when a new Revision is created and ready, 100% of the traffic from the target is immediately shifted to the new Revision.

This might make the request queue too long, either at the QP or Activator, and cause the requests to expire or be rejected by the QP.

Knative provides a rollout-duration parameter, which can be used to gradually shift traffic to the latest Revision, preventing requests from being queued or rejected. Affected Configuration targets are rolled out to 1% of traffic first, and then in equal incremental steps for the rest of the assigned traffic.

Note

rollout-duration is time-based, and does not interact with the autoscaling subsystem.

This feature is available for tagged and untagged traffic targets, configured for either Knative Services or Routes without a service.

Procedure¶

You can configure the rollout-duration parameter by modifying the config-network ConfigMap, or by using the Operator.

ConfigMap configurationOperator configuration

apiVersion: v1
kind: ConfigMap
metadata:
 name: config-network
 namespace: knative-serving
data:
  rollout-duration: "380s"  # Value in seconds.

apiVersion: operator.knative.dev/v1alpha1
kind: KnativeServing
metadata:
  name: knative-serving
spec:
  config:
    network:
       rollout-duration: "380s"

路由更新状态¶

在rollout过程中，系统会更新路由和Knative服务状态条件。 traffic and conditions状态参数都受到影响。

以以下流量配置为例:

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
...
spec:
...
  traffic:
  - percent: 55
    configurationName: config # Pinned to latest ready Revision
  - percent: 45
    revisionName: config-00005 # Pinned to a specific Revision.

最初，1%的流量被推出到修订:

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
...
spec:
...
  traffic:
  - percent: 54
    revisionName: config-00008
  - percent: 1
    revisionName: config-00009
  - percent: 45
    revisionName: config-00005 # Pinned to a specific Revision.

然后其余的流量以18%的增量推出:

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
...
spec:
...
  traffic:
  - percent: 36
    revisionName: config-00008
  - percent: 19
    revisionName: config-00009
  - percent: 45
    revisionName: config-00005 # Pinned to a specific Revision.

rollout继续进行，直到达到目标流量配置:

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
...
spec:
...
  traffic:
  - percent: 55
    revisionName: config-00009
  - percent: 45
    revisionName: config-00005 # Pinned to a specific Revision.

rollout过程中，路由和Knative服务状态条件如下:

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
...
spec:
...
status:
  conditions:
  ...
  - lastTransitionTime: "..."
    message: A gradual rollout of the latest revision(s) is in progress.
    reason: RolloutInProgress
    status: Unknown
    type: Ready

多个延展¶

如果在实施过程中创建了一个新的修订，那么系统将立即开始将流量转移到最新的修订，并将不完整的实施从最新的转移到最旧的。