DEV Community: martinezhenry

Spring Boot Async

martinezhenry — Tue, 15 Nov 2022 00:11:09 +0000

Today we talk about how to use the annotation @Async of Spring Boot to create method asynchronous in our applications.

Using asynchronous methods allows you to execute tasks that require much time to finish without waiting.

Environment

Java 11
Spring Boot 7.0.1
Maven 3.8.6

Preparing a Method

In this example, we used a method called processDelay that executes a random delay time from 0 to 1500 milliseconds. This method looks like this:

public void processDelay() throws InterruptedException {
      long delay = ThreadLocalRandom.current().nextLong(0, 1500 + 1);
      log.info("processing delay: {}", delay);
      Thread.sleep(delay);
      log.info("delay time processed");

}

The sentence Thread.sleep(delay); is the apply the delay time and the sentence long delay = ThreadLocalRandom.current().nextLong(0, 1500 + 1); get a random long number from 0 to 1500 to indicate the first one the time to wait.

Using `@Async`

With this annotation we can convert a simple method into an asynchronous method, in our example we will convert processDelay method to an asynchronous one, we only need to add the annotation @Async at the top of our method, like this:

@Async
public void processDelay() throws InterruptedException {
    long delay = ThreadLocalRandom.current().nextLong(0, 1500 + 1);
    log.info("processing delay: {}", delay);
    Thread.sleep(delay);
    log.info("delay time processed");
}

Enabling Async

To can use @Async annotation also we need to active the Spring Boot features async, for do that, we need to add the annotation @EnableAsync, this one should be added to a class, I prefer to include it on the main class.

Example:

@SpringBootApplication
@EnableAsync
public class AsyncApplication {
    public static void main(String[] args) {
        SpringApplication.run(AsyncApplication.class, args);
    }
}

Testing

To validate the async method we will use a @RestController to call our method and pass it how many executions to apply the method, this is our controller example:

@RestController
@Slf4j
public class DelayController implements IDelayController {

    private final IAsyncProcessorService asyncProcessorService;

    public DelayController(IAsyncProcessorService asyncProcessorService){
        this.asyncProcessorService = asyncProcessorService;
    }

    @Override
    @GetMapping(value = "delay/{executions}")
    public void processDelayTime(@PathVariable(value = "executions") int executions) throws InterruptedException {
        log.info("Tries: {}", executions);
        for(int i = 0; i < executions; i++) {
            this.asyncProcessorService.processDelay();
        }
    }
}

now, if we run the application and request our controller, we can see how the method is executed as a background task.

022-11-07 22:14:08.958  INFO 35748 --- [nio-8080-exec-2] c.h.l.c.implementations.DelayController  : Tries: 2
2022-11-07 22:14:08.968  INFO 35748 --- [         task-2] c.h.l.s.i.AsyncProcessorService          : processing delay: 957
2022-11-07 22:14:08.968  INFO 35748 --- [         task-1] c.h.l.s.i.AsyncProcessorService          : processing delay: 263
2022-11-07 22:14:09.249  INFO 35748 --- [         task-1] c.h.l.s.i.AsyncProcessorService          : delay time processed
2022-11-07 22:14:09.926  INFO 35748 --- [         task-2] c.h.l.s.i.AsyncProcessorService          : delay time processed
2022-11-07 22:14:15.184  INFO 35748 --- [nio-8080-exec-3] c.h.l.c.implementations.DelayController  : Tries: 2
2022-11-07 22:14:15.185  INFO 35748 --- [         task-3] c.h.l.s.i.AsyncProcessorService          : processing delay: 403
2022-11-07 22:14:15.185  INFO 35748 --- [         task-4] c.h.l.s.i.AsyncProcessorService          : processing delay: 736
2022-11-07 22:14:15.591  INFO 35748 --- [         task-3] c.h.l.s.i.AsyncProcessorService          : delay time processed
2022-11-07 22:14:15.924  INFO 35748 --- [         task-4] c.h.l.s.i.AsyncProcessorService          : delay time processed

The response is very fast, indicating that the controller is not waiting for the delay, other evidence that the method is executing asynchronously.

Conclusion

In this post, we can see how to use the Spring Boot @Async annotation to execute methods in background tasks without that we need to wait until the execution finishes.

References

Interacting with a Kubernetes Cluster - Kind

martinezhenry — Tue, 08 Nov 2022 00:30:01 +0000

In the previous article, we told how to install kind y how to create a cluster with this tool (you can see it here Kubernetes Cluster with Kind), now we will talk about how we can Interact with a Kubernetes Cluster using Kind.

Create a Cluster

To create a cluster with Kind we can use the command create cluster, by default kind create a cluster called kind (If you do not use --name parameter)

For example, to create a cluster with a default name and a cluster with a custom name we can use the next commands:

kind create cluster # Default cluster context name is `kind`.
# creating a custom name cluster
kind create cluster --name kind-2

we will see something like the following:

$ kind create cluster
Creating cluster "kind" ...
 ✓ Ensuring node image (kindest/node:v1.21.1) 🖼
 ✓ Preparing nodes 📦  
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
Set kubectl context to "kind-kind"
You can now use your cluster with:

kubectl cluster-info --context kind-kind

Have a nice day! 👋

$ kind create cluster --name kind-2
Creating cluster "kind-2" ...
 ✓ Ensuring node image (kindest/node:v1.21.1) 🖼
 ✓ Preparing nodes 📦  
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
Set kubectl context to "kind-kind-2"
You can now use your cluster with:

kubectl cluster-info --context kind-kind-2

Not sure what to do next? 😅  Check out https://kind.sigs.k8s.io/docs/user/quick-start/

Listing our Clusters

Using the command get clusters we can see the name of the clusters we have.

For example:

kind get clusters

we obtain something like this:

$ kind get clusters                  
kind
kind-2

Loading an Image Into a Cluster

With Kind also we can load our docker images into our cluster nodes, to do that we can use the command load docker-image, previous to use this command we need to have the docker image.

we can use docker build command to create our image, for example:

docker build -t my-image:my-tag .

Now we can load our image into a cluster

kind load docker-image my-image:my-tag

we will see this result:

$ kind load docker-image lab-1:latest
Image: "lab-1:latest" with ID "sha256:019302746a926ab8fd93400a0be0ea4ffc5e9e6a6f6b645258f96391fce7995b" not yet present on node "kind-control-plane", loading...

Also kind allows loading docker images with a file using kind load image-archive my-image-file.tar command, the result is like `docker-image

Note: we can use load command with the param --name to specify a cluster, by default Kind uses the cluster called kind if we do not specify a name

Deleting a Cluster

To delete a cluster with Kind we can use the command delete cluster, this command also uses the parameter --name to indicate a specific cluster's name (by default Kind uses the name 'kind').

For example, we can delete the two clusters previously created with these commands:

kind delete cluster

kind delete cluster --name kind-2

if everything is right, we will see something like this:

$ kind delete cluster Deleting cluster "kind" ...

$ kind delete cluster --name kind-2 Deleting cluster "kind-2" ...

Conslusion

In this post, we saw some commands to interact with our cluster create with Kind, existing other commands, and more parameters that we can use but we focussed on the basics.

References

Interacting With Your Cluster - Kind Docs

Kubernetes Cluster with Kind

martinezhenry — Sun, 06 Nov 2022 23:59:06 +0000

Introduction

In this article, I will show you how you can create a Kubernetes (k8s) cluster using the tool Kind. Kind is a tool that uses docker to create the cluster nodes that may be used for local development or CI, to know more about it, you can go to the Kind official page.

Environment

Linux Mint 20.2
Docker version 20.10.12, build e91ed57

Install

To use Kind, we need to have installed Docker, How to install Docker.

After installing Docker or if already you had installed it, you need to check if the docker daemon is installed and running.

docker info

Now you can install Kind using the steps in the Kind official docs in the install section.

This my case, I used the steps for Homebrew:

brew install kind

After that, we can check the Kind installation with this command

kind version

You should see something like this kind v0.11.1 go1.16.4 linux/amd64

Creating a K8s Cluster

To create a k8s cluster with kind with a basic configuration you can execute this command

kind create cluster

Output:

$ kind create cluster 
Creating cluster "kind" ...
 ✓ Ensuring node image (kindest/node:v1.21.1) 🖼
 ✓ Preparing nodes 📦  
 ✓ Writing configuration 📜 
 ✓ Starting control-plane 🕹️ 
 ✓ Installing CNI 🔌 
 ✓ Installing StorageClass 💾 
Set kubectl context to "kind-kind"
You can now use your cluster with:

kubectl cluster-info --context kind-kind

Have a nice day! 👋

It is all, you created a k8s cluster with basic kind config, to check your cluster you can use

kind get clusters

to see your cluster name and

kind get nodes

to list nodes' names.

Output:

$ kind get clusters
kind

$ kind get nodes     
kind-control-plane

Now you can use kubectl command to interact with your cluster. To see how to install kubectl please see this documentation install kubectl

DEV Community: martinezhenry

Spring Boot Async

Environment

Preparing a Method

Using @Async

Enabling Async

Testing

Conclusion

References

Interacting with a Kubernetes Cluster - Kind

Create a Cluster

Listing our Clusters

Loading an Image Into a Cluster

Deleting a Cluster

Conslusion

References

Kubernetes Cluster with Kind

Introduction

Environment

Install

Creating a K8s Cluster

References

Using `@Async`