How to Use the Command 'kubectl get' (with Examples)

The kubectl get command is a vital tool in the Kubernetes ecosystem, providing users with the capability to fetch and display information about various Kubernetes objects and resources within a cluster. As an essential component for Kubernetes management, this command allows for clear insights into the cluster’s state, enabling administrators and developers to verify configurations, troubleshoot issues, and ensure operational continuity. The command offers a versatile syntax that can fetch data across different levels of resource specificity, from namespaces down to individual pods and services.

Use Case 1: Get All Namespaces in the Current Cluster

Code:

kubectl get namespaces

Motivation: Understanding the organizational structure of your cluster is paramount. Each namespace can represent different environments (e.g., development, testing, production), teams, projects, or any other logical division for managing resources. It’s vital to have a clear overview of all namespaces to manage these divisions effectively.

Explanation: The command retrieves a list of all existing namespaces within the currently connected Kubernetes cluster. No additional arguments are required as it defaults to fetching the global namespace information.

Example Output:

NAME              STATUS   AGE
default           Active   10d
kube-system       Active   10d
kube-public       Active   10d
custom-namespace  Active   7d

Use Case 2: Get Nodes in a Specified Namespace

Code:

kubectl get nodes --namespace namespace

Motivation: Nodes are the physical or virtual machine instances where your containers run. Knowing the nodes associated with a specific namespace helps in understanding resource allocation and workload distribution configurations, especially in customized or multi-tenant habitats.

Explanation: In this scenario, the command attempts to list nodes within a specified namespace. However, it’s essential to note that nodes are a cluster-wide resource; they are technically not scoped to namespaces. The command can be used to enforce namespace context, but the output remains the same as clusters don’t segregate node visibility by namespace.

Example Output:

NAME           STATUS   ROLES                  AGE   VERSION
node1.example  Ready    control-plane,master   10d   v1.21.0
node2.example  Ready    <none>                 10d   v1.21.0

Use Case 3: Get Pods in a Specified Namespace

Code:

kubectl get pods --namespace namespace

Motivation: Pods are the smallest deployable units in Kubernetes and often represent a single instance of a running process. Retrieving all pods in a specific namespace is crucial for monitoring and managing application instances, troubleshooting failures, and analyzing performance and deployments within that scope.

Explanation: The command fetches a list of all pods operating in the specified namespace. By using the --namespace flag followed by the desired namespace name, it narrows the context of the operation to only those pods relevant to that namespace.

Example Output:

NAME                     READY   STATUS    RESTARTS   AGE
app-frontend-1           1/1     Running   1          2d
app-backend-1            1/1     Running   0          2d
database-1               1/1     Running   0          2d

Use Case 4: Get Deployments in a Specified Namespace

Code:

kubectl get deployments --namespace namespace

Motivation: Deployments manage the creation and updating of pods in a Kubernetes environment. Viewing deployments in a specific namespace helps in monitoring rollouts, updates, and the overall health of applications as defined by deployment configurations.

Explanation: This command lists all deployment objects located within a specified namespace, accessed through the --namespace flag. It provides a summary of deployments, their current state, and other pertinent details, enabling users to quickly assess and manage deployments.

Example Output:

NAME          READY   UP-TO-DATE   AVAILABLE   AGE
frontend      3/3     3            3           10d
backend       3/3     3            3           10d
database      1/1     1            1           10d

Use Case 5: Get Services in a Specified Namespace

Code:

kubectl get services --namespace namespace

Motivation: Services abstract and expose a set of pods as a network service. This is crucial for enabling access and providing load balancing. Viewing services in a specific namespace is key in understanding how applications are exposed and interacted with externally and internally.

Explanation: The command outputs all service resources in the specified namespace, utilizing the --namespace flag. This includes information about types, cluster IPs, and ports, offering insights into how applications are mapped and accessed within that namespace.

Example Output:

NAME          TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
backend-svc   ClusterIP   10.96.0.1     <none>        80/TCP    10d
frontend-svc  NodePort    10.96.0.2     <none>        80:30001/TCP 10d

Use Case 6: Get All Resources in a Specified Namespace

Code:

kubectl get all --namespace namespace

Motivation: A holistic view of all resources within a specific namespace is invaluable for comprehensive management and diagnostic purposes. It aids in ensuring that deployed resources align with intended configurations and detecting any anomalies or issues.

Explanation: This command retrieves a comprehensive list of all resources—such as pods, services, and deployments—within the specified namespace. The --namespace flag scopes the query to restrict the output to the desired namespace’s resources.

Example Output:

NAME                                   READY   STATUS    RESTARTS   AGE
pod/app-frontend-1                     1/1     Running   1          2d

NAME                 TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
service/backend-svc  ClusterIP   10.96.0.1     <none>        80/TCP    10d

NAME                 READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/app  3/3     3            3           10d

Use Case 7: Get Kubernetes Objects Defined in a YAML Manifest File

Code:

kubectl get --file path/to/manifest.yaml

Motivation: YAML manifest files define Kubernetes object configurations. Fetching information directly from these files is critical for verification purposes and ensuring that the deployed state matches intended configurations as described in the manifest.

Explanation: By specifying the --file option followed by the path to a YAML manifest, this command reads the file, interprets the configurations, and fetches the current status or definitions of the specified resources in the cluster.

Example Output:

NAME          TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)   AGE
service/web   NodePort    10.96.0.1     <none>        80:30001/TCP 2d

NAME                       READY   STATUS    RESTARTS   AGE
pod/web-5d69f7b6cb-2btnj   1/1     Running   0          2d

Conclusion

The kubectl get command is a cornerstone of Kubernetes management, providing a wide array of options to extract and display critical information about your cluster’s resources. Whether you’re managing namespaces, examining pods, or verifying deployments and services, kubectl get offers the versatility and detail necessary to maintain seamless Kubernetes operations.