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This article mainly introduces "how container-to-container communication is in Kubernetes". In daily operation, I believe many people have doubts about container-to-container communication in Kubernetes. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "container-to-container communication in Kubernetes". Next, please follow the editor to study!

Kubernetes is a containerized solution. It provides a runtime environment for Pods that can hold one or more containers. An important aspect of Kubernetes is container communication within Pod.

In addition, an important area for managing Kubernetes networks is to forward container ports internally and externally to ensure proper communication between containers in Pod. To manage this type of traffic, Kubernetes offers the following four networking models:

Container-to-container communication Pod to Pod communication Pod to Service communication communication between external communication containers

Having multiple containers in a single Pod can be done in several different ways to make it relatively easy to communicate with each other. In this article, we will discuss two approaches in detail: shared volumes and interprocess communication.

1. Shared volumes in Kubernetes Pod

In Kubernetes, you can use shared Kubernetes volumes as a simple and efficient way to share data between containers in Pod. In most cases, it is sufficient for all containers in Pod to share directories on the host.

Kubernetes Volumes enables data to survive a container restart, but these volumes have the same lifetime as Pod. This means that the volume (and the data it stores) has been around for exactly the same time as Pod. If the Pod is deleted for any reason, even if the same replacement is created, the shared volume will be corrupted and created from scratch.

A standard use case for multi-container Pod with shared volumes is that one container writes logs or other files to the shared directory, while the other container reads from the shared directory. For example, we can create a Pod like this:

ApiVersion: v1kind: Podmetadata: name: mc1spec: volumes:-name: html emptyDir: {} containers:-name: 1st image: nginx volumeMounts:-name: html mountPath: / usr/share/nginx/html-name: 2nd image: debian volumeMounts:-name: html mountPath: / html command: ["/ bin/sh", "- c"] args:-while true; do date > > / html/index.html Sleep 1; done

In this example, we define a volume named html. It is of type emptyDir, which means that the volume was first created when the Pod was assigned to the node, and exists as long as the Pod is running on that node. As the name implies, it was initially empty. The first container runs the Nginx server and installs the shared volume to the directory / usr/share/nginx/html. The second container uses a Debian image and installs the shared volume to the directory / html. The second container adds the current date and time every second to the index.html file in the shared volume.

When a user makes an HTTP request to Pod, the Nginx server reads the file and passes it back to the user.

You can check that Pod works by exposing the nginx port and accessing it using a browser, or by checking the shared directory directly in the container:

$kubectl exec mc1-c 1st-/ bin/cat / usr/share/nginx/html/index.html...

$kubectl exec mc1-c 2nd-/ bin/cat / html/index.html. 2. Interprocess communication (Inter-Process Communications,IPC)

Containers in Pod share the same IPC namespace, which means they can also communicate with each other using standard interprocess communication, such as SystemV semaphores or POSIX shared memory. The container communicates in Pod using the policy of the local hostname.

In the following example, we define a Pod with two containers. Both use the same Docker image. The first container, the producer, creates a standard Linux message queue, writes some random messages, and then writes a special exit message. The second container, the consumer, opens the same message queue to read the message until an exit message is received. We also set the restart policy to never, so the container stops after both containers are terminated.

ApiVersion: v1kind: Podmetadata: name: mc2spec: containers:-name: producer image: allingeek/ch7_ipc command: [. / ipc ","-producer "]-name: consumer image: allingeek/ch7_ipc command: [". / ipc ","-consumer "] restartPolicy: Never

To check this, use kubectl create to create a pod and observe the status of the Pod:

$kubectl get pods-- show-all-wNAME READY STATUS RESTARTS AGEmc2 0 0smc2 2 Pending 0 0smc2 0 0smc2 2 ContainerCreating 0 0smc2 0 Completed 0 29

Now you can check the log of each container and verify that the second container received all the messages from the first container, including the exit message:

$kubectl logs mc2-c producer...Produced: f4Produced: 1dProduced: 9eProduced: 27

$kubectl logs mc2-c consumer...Consumed: f4Consumed: 1dConsumed: 9eConsumed: 27Consumed: done

However, there is a major problem with this Pod, which is related to the way the container starts.

At this point, the study of "how container-to-container communication is in Kubernetes" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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