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fabric8在k8s客户端的基本使用

最编程 2024-08-12 17:51:15
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介绍

参考下文 

开源微服务管理平台 fabric8 简介 · Jimmy Song本文介绍了开源的微服务管理平台 Fabric8。https://jimmysong.io/blog/fabric8-introduction/

官网

​​https://github.com/fabric8io/kubernetes-clienthttps://github.com/fabric8io/kubernetes-client​​

Contents

  • ​​Usage​​
  • ​​Creating a client​​
  • ​​Configuring the client​​
  • ​​Loading resources from external sources​​
  • ​​Passing a reference of a resource to the client​​
  • ​​Adapting a client​​
  • ​​Adapting and close​​
  • ​​Generating CRD from Java​​
  • ​​Generating Java from CRD​​
  • ​​Mocking Kubernetes​​
  • ​​Who Uses Fabric8 Kubernetes Client?​​
  • ​​Kubernetes Operators in Java Written using Fabric8 Kubernetes Client​​
  • ​​Kubernetes and Red Hat OpenShift Compatibility Matrix​​
  • ​​Kubernetes Client CHEAT SHEET​​
  • ​​Kubectl Java Equivalents​​
  • ​​FAQs​​

Usage

Creating a client

The easiest way to create a client is:


KubernetesClient client = new KubernetesClientBuilder().build();


​​DefaultOpenShiftClient​​​ implements both the ​​KubernetesClient​​​ & ​​OpenShiftClient​​​ interface so if you need the OpenShift extensions, such as ​​Build​​s, etc then simply do:


OpenShiftClient osClient = new KubernetesClientBuilder().build().adapt(OpenShiftClient.class);


Configuring the client

This will use settings from different sources in the following order of priority:

  • System properties
  • Environment variables
  • Kube config file
  • Service account token & mounted CA certificate

System properties are preferred over environment variables. The following system properties & environment variables can be used for configuration:

Property / Environment Variable

Description

Default value

​​kubernetes.disable.autoConfig​​​ / ​​KUBERNETES_DISABLE_AUTOCONFIG​​

Disable automatic configuration

​​false​​

​​kubernetes.master​​​ / ​​KUBERNETES_MASTER​​

Kubernetes master URL

​​https://kubernetes.default.svc​​

​​kubernetes.api.version​​​ / ​​KUBERNETES_API_VERSION​​

API version

​​v1​​

​​openshift.url​​​ / ​​OPENSHIFT_URL​​

OpenShift master URL

Kubernetes master URL value

​​kubernetes.oapi.version​​​ / ​​KUBERNETES_OAPI_VERSION​​

OpenShift API version

​​v1​​

​​kubernetes.trust.certificates​​​ / ​​KUBERNETES_TRUST_CERTIFICATES​​

Trust all certificates

​​false​​

​​kubernetes.disable.hostname.verification​​​ / ​​KUBERNETES_DISABLE_HOSTNAME_VERIFICATION​​

​​false​​

​​kubernetes.certs.ca.file​​​ / ​​KUBERNETES_CERTS_CA_FILE​​

​​kubernetes.certs.ca.data​​​ / ​​KUBERNETES_CERTS_CA_DATA​​

​​kubernetes.certs.client.file​​​ / ​​KUBERNETES_CERTS_CLIENT_FILE​​

​​kubernetes.certs.client.data​​​ / ​​KUBERNETES_CERTS_CLIENT_DATA​​

​​kubernetes.certs.client.key.file​​​ / ​​KUBERNETES_CERTS_CLIENT_KEY_FILE​​

​​kubernetes.certs.client.key.data​​​ / ​​KUBERNETES_CERTS_CLIENT_KEY_DATA​​

​​kubernetes.certs.client.key.algo​​​ / ​​KUBERNETES_CERTS_CLIENT_KEY_ALGO​​

Client key encryption algorithm

​​RSA​​

​​kubernetes.certs.client.key.passphrase​​​ / ​​KUBERNETES_CERTS_CLIENT_KEY_PASSPHRASE​​

​​kubernetes.auth.basic.username​​​ / ​​KUBERNETES_AUTH_BASIC_USERNAME​​

​​kubernetes.auth.basic.password​​​ / ​​KUBERNETES_AUTH_BASIC_PASSWORD​​

​​kubernetes.auth.serviceAccount.token​​​ / ​​KUBERNETES_AUTH_SERVICEACCOUNT_TOKEN​​

Name of the service account token file

​​/var/run/secrets/kubernetes.io/serviceaccount/token​​

​​kubernetes.auth.tryKubeConfig​​​ / ​​KUBERNETES_AUTH_TRYKUBECONFIG​​

Configure client using Kubernetes config

​​true​​

​​kubeconfig​​​ / ​​KUBECONFIG​​

Name of the kubernetes config file to read

​​~/.kube/config​​

​​kubernetes.auth.tryServiceAccount​​​ / ​​KUBERNETES_AUTH_TRYSERVICEACCOUNT​​

Configure client from Service account

​​true​​

​​kubernetes.tryNamespacePath​​​ / ​​KUBERNETES_TRYNAMESPACEPATH​​

Configure client namespace from Kubernetes service account namespace path

​​true​​

​​kubernetes.auth.token​​​ / ​​KUBERNETES_AUTH_TOKEN​​

​​kubernetes.watch.reconnectInterval​​​ / ​​KUBERNETES_WATCH_RECONNECTINTERVAL​​

Watch reconnect interval in ms

​​1000​​

​​kubernetes.watch.reconnectLimit​​​ / ​​KUBERNETES_WATCH_RECONNECTLIMIT​​

Number of reconnect attempts (-1 for infinite)

​​-1​​

​​kubernetes.connection.timeout​​​ / ​​KUBERNETES_CONNECTION_TIMEOUT​​

Connection timeout in ms (0 for no timeout)

​​10000​​

​​kubernetes.request.timeout​​​ / ​​KUBERNETES_REQUEST_TIMEOUT​​

Read timeout in ms

​​10000​​

​​kubernetes.upload.connection.timeout​​​ / ​​KUBERNETES_UPLOAD_CONNECTION_TIMEOUT​​

Pod upload connection timeout in ms

​​10000​​

​​kubernetes.upload.request.timeout​​​ / ​​KUBERNETES_UPLOAD_REQUEST_TIMEOUT​​

Pod upload request timeout in ms

​​120000​​

​​kubernetes.request.retry.backoffLimit​​​ / ​​KUBERNETES_REQUEST_RETRY_BACKOFFLIMIT​​

Number of retry attempts

​​0​​

​​kubernetes.request.retry.backoffInterval​​​ / ​​KUBERNETES_REQUEST_RETRY_BACKOFFINTERVAL​​

Retry initial backoff interval in ms

​​1000​​

​​kubernetes.rolling.timeout​​​ / ​​KUBERNETES_ROLLING_TIMEOUT​​

Rolling timeout in ms

​​900000​​

​​kubernetes.logging.interval​​​ / ​​KUBERNETES_LOGGING_INTERVAL​​

Logging interval in ms

​​20000​​

​​kubernetes.scale.timeout​​​ / ​​KUBERNETES_SCALE_TIMEOUT​​

Scale timeout in ms

​​600000​​

​​kubernetes.websocket.timeout​​​ / ​​KUBERNETES_WEBSOCKET_TIMEOUT​​

Websocket timeout in ms

​​5000​​

​​kubernetes.websocket.ping.interval​​​ / ​​KUBERNETES_WEBSOCKET_PING_INTERVAL​​

Websocket ping interval in ms

​​30000​​

​​kubernetes.max.concurrent.requests​​​ / ​​KUBERNETES_MAX_CONCURRENT_REQUESTS​​

​​64​​

​​kubernetes.max.concurrent.requests.per.host​​​ / ​​KUBERNETES_MAX_CONCURRENT_REQUESTS_PER_HOST​​

​​5​​

​​kubernetes.impersonate.username​​​ / ​​KUBERNETES_IMPERSONATE_USERNAME​​

​​Impersonate-User​​ HTTP header value

​​kubernetes.impersonate.group​​​ / ​​KUBERNETES_IMPERSONATE_GROUP​​

​​Impersonate-Group​​ HTTP header value

​​kubernetes.tls.versions​​​ / ​​KUBERNETES_TLS_VERSIONS​​

TLS versions separated by ​​,​​

​​TLSv1.2​​

​​kubernetes.truststore.file​​​ / ​​KUBERNETES_TRUSTSTORE_FILE​​

​​kubernetes.truststore.passphrase​​​ / ​​KUBERNETES_TRUSTSTORE_PASSPHRASE​​

​​kubernetes.keystore.file​​​ / ​​KUBERNETES_KEYSTORE_FILE​​

​​kubernetes.keystore.passphrase​​​ / ​​KUBERNETES_KEYSTORE_PASSPHRASE​​

​​kubernetes.backwardsCompatibilityInterceptor.disable​​​ / ​​KUBERNETES_BACKWARDSCOMPATIBILITYINTERCEPTOR_DISABLE​​

Disable the ​​BackwardsCompatibilityInterceptor​​

​​true​​

​​no.proxy​​​ / ​​NO_PROXY​​

comma-separated list of domain extensions ​​proxy​​ should not be used for

Alternatively you can use the ​​ConfigBuilder​​ to create a config object for the Kubernetes client:


Config config = new ConfigBuilder().withMasterUrl("https://mymaster.com").build(); KubernetesClient client = new KubernetesClientBuilder().withConfig(config).build();


Using the DSL is the same for all resources.

List resources:


NamespaceList myNs = client.namespaces().list(); ServiceList myServices = client.services().list(); ServiceList myNsServices = client.services().inNamespace("default").list();


Get a resource:


Namespace myns = client.namespaces().withName("myns").get(); Service myservice = client.services().inNamespace("default").withName("myservice").get();


Delete:


Namespace myns = client.namespaces().withName("myns").delete(); Service myservice = client.services().inNamespace("default").withName("myservice").delete();


Editing resources uses the inline builders from the Kubernetes Model:


Namespace myns = client.namespaces().withName("myns").edit(n -> new NamespaceBuilder(n) .editMetadata() .addToLabels("a", "label") .endMetadata() .build()); Service myservice = client.services().inNamespace("default").withName("myservice").edit(s -> new ServiceBuilder(s) .editMetadata() .addToLabels("another", "label") .endMetadata() .build());


In the same spirit you can inline builders to create:


Namespace myns = client.namespaces().create(new NamespaceBuilder() .withNewMetadata() .withName("myns") .addToLabels("a", "label") .endMetadata() .build()); Service myservice = client.services().inNamespace("default").create(new ServiceBuilder() .withNewMetadata() .withName("myservice") .addToLabels("another", "label") .endMetadata() .build());


You can also set the apiVersion of the resource like in the case of SecurityContextConstraints :


SecurityContextConstraints scc = new SecurityContextConstraintsBuilder() .withApiVersion("v1") .withNewMetadata().withName("scc").endMetadata() .withAllowPrivilegedContainer(true) .withNewRunAsUser() .withType("RunAsAny") .endRunAsUser() .build();


Following events

Use ​​io.fabric8.kubernetes.api.model.Event​​ as T for Watcher:


client.events().inAnyNamespace().watch(new Watcher<Event>() { @Override public void eventReceived(Action action, Event resource) { System.out.println("event " + action.name() + " " + resource.toString()); } @Override public void onClose(KubernetesClientException cause) { System.out.println("Watcher close due to " + cause); } });


Working with extensions

The kubernetes API defines a bunch of extensions like ​​daemonSets​​​, ​​jobs​​​, ​​ingresses​​​ and so forth which are all usable in the ​​extensions()​​ DSL:

e.g. to list the jobs...

jobs = client.batch().jobs().list();

Loading resources from external sources

There are cases where you want to read a resource from an external source, rather than defining it using the clients DSL. For those cases the client allows you to load the resource from:

  • A file(Supports both java.io.File and java.lang.String)
  • A url
  • An input stream

Once the resource is loaded, you can treat it as you would, had you created it yourself.

For example lets read a pod, from a yml file and work with it:

Pod refreshed = client.load('/path/to/a/pod.yml').fromServer().get();
client.load('/workspace/pod.yml').delete();
LogWatch handle = client.load('/workspace/pod.yml').watchLog(System.out);

Passing a reference of a resource to the client

In the same spirit you can use an object created externally (either a reference or using its string representation).

For example:

Pod pod = someThirdPartyCodeThatCreatesAPod();
client.resource(pod).delete();

Adapting the client

The client supports plug-able adapters. An example adapter is the ​​OpenShift Adapter​​​ which allows adapting an existing ​​KubernetesClient​​​ instance to an ​​OpenShiftClient​​ one.

For example:


KubernetesClient client = new KubernetesClientBuilder().build(); OpenShiftClient oClient = client.adapt(OpenShiftClient.class);


The client also support the isAdaptable() method which checks if the adaptation is possible and returns true if it does.


KubernetesClient client = new KubernetesClientBuilder().build(); if (client.isAdaptable(OpenShiftClient.class)) { OpenShiftClient oClient = client.adapt(OpenShiftClient.class); } else { throw new Exception("Adapting to OpenShiftClient not support. Check if adapter is present, and that env provides /oapi root path."); }


Adapting and close

Note that when using adapt() both the adaptee and the target will share the same resources (underlying http client, thread pools etc). This means that close() is not required to be used on every single instance created via adapt. Calling close() on any of the adapt() managed instances or the original instance, will properly clean up all the resources and thus none of the instances will be usable any longer.

Mocking Kubernetes

Along with the client this project also provides a kubernetes mock server that you can use for testing purposes. The mock server is based on ​​https://github.com/square/okhttp/tree/master/mockwebserver​​​ but is empowered by the DSL and features provided by ​​https://github.com/fabric8io/mockwebserver​​.

The Mock Web Server has two modes of operation:

  • Expectations mode
  • CRUD mode

Expectations mode

It's the typical mode where you first set which are the expected http requests and which should be the responses for each request. More details on usage can be found at: ​​GitHub - fabric8io/mockwebserver: An extension of okhttp's mockwebserver, that provides a DSL and is easier to use​​

This mode has been extensively used for testing the client itself. Make sure you check ​​kubernetes-test​​.

To add a Kubernetes server to your test:


@Rule public KubernetesServer server = new KubernetesServer();


CRUD mode

Defining every single request and response can become tiresome. Given that in most cases the mock webserver is used to perform simple crud based operations, a crud mode has been added. When using the crud mode, the mock web server will store, read, update and delete kubernetes resources using an in memory map and will appear as a real api server.

To add a Kubernetes Server in crud mode to your test:


@Rule public KubernetesServer server = new KubernetesServer(true, true);


Then you can use the server like:


@Test public void testInCrudMode() { KubernetesClient client = server.getClient(); final CountDownLatch deleteLatch = new CountDownLatch(1); final CountDownLatch closeLatch = new CountDownLatch(1); //CREATE client.pods().inNamespace("ns1").create(new PodBuilder().withNewMetadata().withName("pod1").endMetadata().build()); //READ podL

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