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2.4 Container network and storage

Container networking and storage are two very important concepts in containerized applications. Container networking helps different containers communicate, while container storage allows containers to read and write data in a persistent storage medium.

In Kubernetes, container networking is implemented through NetworkPolicy and PodSecurityPolicy resources. The NetworkPolicy resource is used to control container network connections, which can limit container access to the network and provide security and reliability. The PodSecurityPolicy resource is used to provide security protection for the container, which can control the access rights and permission assignment of the container.

Java developers can use the Kubernetes API client library to code container networking and storage. For example, here is an example of Java code to create and manage a container network using the Kubernetes API client library:

public class KubernetesNetworkJavaCode {
    
    
    public static void main(String[] args) throws KubernetesClientException, IOException {
    
    

        // 创建 Kubernetes 客户端实例    
        KubernetesClient KubernetesClient = KubernetesClient.create();

        // 创建 NetworkPolicy 资源    
        V1beta1NetworkPolicy networkPolicy = new V1beta1NetworkPolicy();    
        networkPolicy.setObjectMeta(new V1ObjectMeta());    
        networkPolicy.setSpec(new V1beta1NetworkPolicySpec());    
        networkPolicy.setStatus(new V1beta1NetworkPolicyStatus());

        // 设置 NetworkPolicy 资源的配置    
        networkPolicy.spec.podSelector = new V1LabelSelector();    
        networkPolicy.spec.podSelector.matchLabels = new HashMap<>();    
        List<V1PodTemplateSpec> templates = new ArrayList<>();    
        V1PodTemplateSpec template = new V1PodTemplateSpec();    
        template.metadata = new V1ObjectMeta();    
        template.spec = new V1PodSpec();    
        templates.add(template);    
        networkPolicy.spec.podTemplates = templates;    
        networkPolicy.spec.policyTypes = new String[]{
    
    "Ingress", "Egress"};

        // 设置 NetworkPolicy 资源的状态    
        networkPolicy.status.allowedPods = new ArrayList<>();    
        networkPolicy.status.allowedPods.forEach(pod -> {
    
        
            PodStatus status = new PodStatus();    
            status.podIP = pod.getPodIP();    
            status.Ready = true;    
            status.ContainersReady = true;    
            status.Conditions = new HashMap<>();    
            status.Conditions.put("Ready", new V1PodCondition());    
            networkPolicy.status.allowedPods.add(status);    
        });

        // 创建 NetworkPolicy 资源    
        V1beta1NetworkPolicy createdNetworkPolicy = KubernetesClient.create(networkPolicy).get();

        // 打印 NetworkPolicy 资源的状态    
        System.out.println("NetworkPolicy 资源的状态为:" + createdNetworkPolicy.status.toString());    
    }    
}

In the above code, we first created a KubernetesClient instance, and then created a NetworkPolicy resource. We use the configuration of the NetworkPolicy resource to specify the rules for container networking and set the state of the NetworkPolicy resource. Finally, we created the NetworkPolicy resource using the KubernetesClient and saved it in the createdNetworkPolicy object.

Alternatively, Java developers can use the Kubernetes API client library to create and manage container storage, such as Docker container storage. With Docker container storage, developers can store Docker images in a Kubernetes cluster and access them using Docker containers. Using Java to write container storage code can realize persistent storage of container data and provide data access services.

[Containerized application design and development] 2.4 Container network and storage

2.4 Container network and storage

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