Essential Maven, Docker, Kubernetes, and Helm Commands for Modern Development

Mastering the tools of modern software development is crucial for any backend developer. This blog post covers essential commands for Maven, Docker, Kubernetes, and Helm, often encountered in real-world development and deployment scenarios.

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Maven Commands

Maven Command	Description
mvn clean install -Dmaven.test.skip=true	Generates a JAR file inside the target folder, skipping tests.
mvn spring-boot:run	Starts a Spring Boot Maven project.
mvn spring-boot:build-image	Generates a Docker image using Buildpacks without needing a Dockerfile.
mvn compile jib:dockerBuild	Creates a Docker image using Google Jib without needing a Dockerfile.

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Docker Commands

Docker Command	Description
docker build . -t gavebegin/accounts:s4	Builds a Docker image from a Dockerfile.
docker run -p 8080:8080 gavebegin/accounts:s4	Runs a Docker container from a given image.
docker images	Lists all Docker images.
docker image inspect image-id	Displays detailed information about an image.
docker image rm image-id	Removes an image.
docker image push docker.io/gavebegin/accounts:s4	Pushes an image to a registry.
docker image pull docker.io/gavebegin/accounts:s4	Pulls an image from a registry.
docker ps	Lists running containers.
docker ps -a	Lists all containers, including stopped ones.
docker container start container-id	Starts a stopped container.
docker container pause container-id	Pauses a container.
docker container unpause container-id	Unpauses a container.
docker container stop container-id	Stops a running container.
docker container kill container-id	Kills a running container immediately.
docker container restart container-id	Restarts a container.
docker container inspect container-id	Inspects container details.
docker container logs container-id	Fetches container logs.
docker container logs -f container-id	Follows container logs.
docker container rm container-id	Removes a container.
docker container prune	Removes all stopped containers.
docker compose up	Creates and starts containers using a docker-compose file.
docker compose down	Stops and removes containers created via docker-compose.
docker compose start	Starts containers defined in a docker-compose file.
docker run -p 3306:3306 --name accountsdb -e MYSQL_ROOT_PASSWORD=root -e MYSQL_DATABASE=accountsdb -d mysql	Creates a MySQL container.
docker run -p 6379:6379 --name gavebeginredis -d redis	Creates a Redis container.
docker run -p 8080:8080 -e KEYCLOAK_ADMIN=admin -e KEYCLOAK_ADMIN_PASSWORD=admin quay.io/keycloak/keycloak:22.0.3 start-dev	Creates a Keycloak container.

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Apache Benchmark (ab) Command

Command	Description
ab -n 10 -c 2 -v 3 http://localhost:8072/gavebegin/cards/api/contact-info	Load tests an API by sending 10 requests with concurrency level 2.

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Kubernetes Commands

Kubernetes Command	Description
kubectl apply -f filename	Deploys resources defined in a YAML file.
kubectl get all	Lists all resources in the cluster.
kubectl get pods	Lists all pods.
kubectl get pod pod-id	Describes a specific pod.
kubectl describe pod pod-id	Shows detailed information about a pod.
kubectl delete pod pod-id	Deletes a pod.
kubectl get services	Lists all services.
kubectl get service service-id	Describes a specific service.
kubectl describe service service-id	Shows detailed information about a service.
kubectl get nodes	Lists all nodes.
kubectl get node node-id	Describes a specific node.
kubectl get replicasets	Lists all replica sets.
kubectl get replicaset replicaset-id	Describes a specific replica set.
kubectl get deployments	Lists all deployments.
kubectl get deployment deployment-id	Describes a specific deployment.
kubectl get configmaps	Lists all ConfigMaps.
kubectl get configmap configmap-id	Describes a specific ConfigMap.
kubectl get events --sort-by=.metadata.creationTimestamp	Displays events sorted by creation time.
kubectl scale deployment accounts-deployment --replicas=1	Scales a deployment.
kubectl set image deployment gatewayserver-deployment gatewayserver=gavebegin/gatewayserver:s11 --record	Updates a deployment's image.
kubectl get events --sort-by=.metadata.creationTimestamp	Lists events for a specific namespace.
kubectl get events -n <namespace>	Lists all events in the default namespace.
kubectl rollout history deployment gatewayserver-deployment	Shows rollout history of a deployment.
kubectl rollout undo deployment gatewayserver-deployment --to-revision=1	Rolls back to a specific revision.
kubectl get pvc	Lists persistent volume claims (PVCs).
kubectl delete pvc data-happy-panda-mariadb-0	Deletes a PVC.

The kubectl logs command is used to fetch logs from containers in Kubernetes pods. Below is a detailed list of kubectl logs command variations and options:

Basic Usage

kubectl logs <pod-name>

• Fetches logs from the default container of the specified pod.

Specify Namespace

kubectl logs <pod-name> -n <namespace>

• Retrieves logs from a pod in a specific namespace.

Specify Container

kubectl logs <pod-name> -c <container-name>

• Fetch logs from a specific container in a pod (useful when a pod has multiple containers).

Follow Logs (Real-time Streaming)

kubectl logs -f <pod-name>

• Continuously stream logs until stopped.

kubectl logs -f <pod-name> -c <container-name>

• Stream logs of a specific container.

Tail Last N Lines

kubectl logs --tail=<number> <pod-name>

• Displays only the last N lines of logs.

Show Logs with Timestamps

kubectl logs --timestamps <pod-name>

• Adds timestamps to each log entry.

Retrieve Logs from Previous Instance of a Pod

kubectl logs --previous <pod-name>

• Fetch logs from a crashed pod's previous instance.

Retrieve Logs for a Pod Running on a Specific Node

kubectl logs <pod-name> --limit-bytes=<number>

• Limits the number of bytes fetched.

Combine Logs from All Containers in a Pod

kubectl logs <pod-name> --all-containers=true

• Fetch logs from all containers in the pod.

Retrieve Logs for a Specific Time Range (If Supported by Log Aggregator)

kubectl logs <pod-name> --since=1h

• Fetch logs from the last hour.

kubectl logs <pod-name> --since-time=2024-02-21T15:00:00Z

• Fetch logs since a specific timestamp.

Logging from Pods with a Label Selector

kubectl logs -l app=my-app

• Fetch logs from pods matching a label.

Save Logs to a File

kubectl logs <pod-name> > logs.txt

• Redirects logs to a file.

Would you like any specific details on debugging or advanced log retrieval?

Helm Commands

Helm Command	Description
helm create [NAME]	Creates a new chart.
helm dependencies build	Recompiles chart dependencies.
helm install [NAME] [CHART]	Installs a chart.
helm upgrade [NAME] [CHART]	Upgrades a release.
helm history [NAME]	Shows revision history.
helm rollback [NAME] [REVISION]	Rolls back a release.
helm uninstall [NAME]	Uninstalls a release.
helm template [NAME] [CHART]	Renders chart templates locally.
helm list	Lists all Helm releases.

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Mastering these commands will give you confidence in building, containerizing, deploying, and managing applications in production environments. Bookmark this page as a quick reference for your day-to-day development journey. Happy coding!