Red Hat SummitChapter 47. Kubernetes
Perform operations against Kubernetes API
47.1. Maven coordinates
Create a new project with this extension on code.quarkus.redhat.com
Or add the coordinates to your existing project:
<dependency>
<groupId>org.apache.camel.quarkus</groupId>
<artifactId>camel-quarkus-kubernetes</artifactId>
</dependency>
<dependency>
<groupId>org.apache.camel.quarkus</groupId>
<artifactId>camel-quarkus-kubernetes</artifactId>
</dependency>47.2. Additional Camel Quarkus configuration
In this release of Camel Extensions for Quarkus, the camel-quarkus-kubernetes extension is only supported when used with the camel-quarkus-master extension as a cluster service. Additionally, in order for the camel-quarkus-kubernetes extension to be supported, you must explicitly add a dependency on the quarkus-openshift-client extension in your application.
47.2.1. Automatic registration of a Kubernetes Client instance
The extension automatically registers a Kubernetes Client bean named kubernetesClient. You can reference the bean in your routes like this:
from("direct:pods")
.to("kubernetes-pods:///?kubernetesClient=#kubernetesClient&operation=listPods")
from("direct:pods")
.to("kubernetes-pods:///?kubernetesClient=#kubernetesClient&operation=listPods")
By default the client is configured from the local kubeconfig file. You can customize the client configuration via properties within application.properties:
quarkus.kubernetes-client.master-url=https://my.k8s.host quarkus.kubernetes-client.namespace=my-namespace
quarkus.kubernetes-client.master-url=https://my.k8s.host
quarkus.kubernetes-client.namespace=my-namespaceThe full set of configuration options are documented in the Quarkus Kubernetes Client guide.
47.2.2. Having only a single consumer in a cluster consuming from a given endpoint
When the same route is deployed on multiple pods, it could be interesting to use this extension in conjunction with the Master one. In such a setup, a single consumer will be active at a time across the whole camel master namespace.
For instance, having the route below deployed on multiple pods:
from("master:ns:timer:test?period=100").log("Timer invoked on a single pod at a time");
from("master:ns:timer:test?period=100").log("Timer invoked on a single pod at a time");It’s possible to enable the kubernetes cluster service with a property like below:
quarkus.camel.cluster.kubernetes.enabled = true
quarkus.camel.cluster.kubernetes.enabled = true
As a result, a single consumer will be active across the ns camel master namespace. It means that, at a given time, only a single timer will generate exchanges across the whole cluster. In other words, messages will be logged every 100ms on a single pod at a time.
The kubernetes cluster service could further be tuned by tweaking quarkus.camel.cluster.kubernetes.* properties.
| Configuration property | Type | Default |
|---|---|---|
|
Whether a Kubernetes Cluster Service should be automatically configured according to 'quarkus.camel.cluster.kubernetes.*' configurations. |
|
|
|
The cluster service ID (defaults to null). |
| |
|
The URL of the Kubernetes master (read from Kubernetes client properties by default). |
| |
|
The connection timeout in milliseconds to use when making requests to the Kubernetes API server. |
| |
|
The name of the Kubernetes namespace containing the pods and the configmap (autodetected by default). |
| |
|
The name of the current pod (autodetected from container host name by default). |
| |
|
The jitter factor to apply in order to prevent all pods to call Kubernetes APIs in the same instant (defaults to 1.2). |
| |
|
The default duration of the lease for the current leader (defaults to 15000). |
| |
|
The deadline after which the leader must stop its services because it may have lost the leadership (defaults to 10000). |
| |
|
The time between two subsequent attempts to check and acquire the leadership. It is randomized using the jitter factor (defaults to 2000). |
| |
|
Service lookup order/priority (defaults to 2147482647). |
| |
|
The name of the lease resource used to do optimistic locking (defaults to 'leaders'). The resource name is used as prefix when the underlying Kubernetes resource can manage a single lock. |
| |
|
The lease resource type used in Kubernetes, either 'config-map' or 'lease' (defaults to 'lease'). |
| |
|
Whether the camel master namespace leaders should be distributed evenly across all the camel contexts in the cluster. |
|
|
|
The labels key/value used to identify the pods composing the cluster, defaults to empty map. |
|
Configuration property fixed at build time. All other configuration properties are overridable at runtime.
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