kubectl get for listing resources in Kubernetes - Step-by-Step Execution

Process Flow - kubectl get for listing resources

User runs 'kubectl get'

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kubectl sends request to API server

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API server queries cluster state

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API server returns list of resources

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kubectl displays resource list to user

The command sends a request to the Kubernetes API server, which returns the current list of resources. kubectl then shows this list to the user.

Execution Sample

Kubernetes

kubectl get pods
kubectl get services
kubectl get nodes

These commands list pods, services, and nodes in the Kubernetes cluster.

Process Table

Step	Command	API Request Sent	API Response	kubectl Output
1	kubectl get pods	GET /api/v1/namespaces/default/pods	List of pods in default namespace	NAME READY STATUS RESTARTS AGE pod1 1/1 Running 0 5m pod2 1/1 Running 1 10m
2	kubectl get services	GET /api/v1/namespaces/default/services	List of services in default namespace	NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service1 ClusterIP 10.96.0.1 <none> 80/TCP 15m
3	kubectl get nodes	GET /api/v1/nodes	List of all nodes in cluster	NAME STATUS ROLES AGE VERSION node1 Ready master 20d v1.26.0 node2 Ready worker 20d v1.26.0
4	kubectl get pods -n kube-system	GET /api/v1/namespaces/kube-system/pods	List of pods in kube-system namespace	NAME READY STATUS RESTARTS AGE coredns-558bd4d5db-abcde 1/1 Running 0 20d
5	kubectl get pods --all-namespaces	GET /api/v1/pods	List of pods in all namespaces	NAMESPACE NAME READY STATUS RESTARTS AGE default pod1 1/1 Running 0 5m kube-system coredns 1/1 Running 0 20d
6	Exit	-	-	Command ends after displaying resource list

💡 kubectl finishes after receiving and displaying the resource list from the API server.

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	After Step 5	Final
Command	None	kubectl get pods	kubectl get services	kubectl get nodes	kubectl get pods -n kube-system	kubectl get pods --all-namespaces	None
API Request	None	GET /api/v1/namespaces/default/pods	GET /api/v1/namespaces/default/services	GET /api/v1/nodes	GET /api/v1/namespaces/kube-system/pods	GET /api/v1/pods	None
API Response	None	Pods list	Services list	Nodes list	Pods list in kube-system	Pods list all namespaces	None
kubectl Output	None	Pods table	Services table	Nodes table	Pods kube-system table	Pods all namespaces table	None

Key Moments - 3 Insights

Why does 'kubectl get pods' only show pods in the default namespace?

By default, kubectl queries the 'default' namespace unless you specify another namespace with '-n' or '--namespace'. See step 1 and step 4 in the execution_table.

What happens when you use '--all-namespaces' with 'kubectl get'?

kubectl requests pods from all namespaces, not just one. This is shown in step 5 where the API request is for all pods cluster-wide.

How does kubectl know what resource to list?

The resource type (pods, services, nodes) is the first argument after 'kubectl get'. kubectl sends this in the API request path, as shown in the API Request column.

Visual Quiz - 3 Questions

Look at the execution table, what API request does 'kubectl get services' send?

A GET /api/v1/namespaces/default/services

B GET /api/v1/namespaces/default/pods

C GET /api/v1/nodes

D GET /api/v1/pods

💡 Hint

Check the API Request Sent column at step 2 in the execution_table.

At which step does kubectl list pods from all namespaces?

A Step 1

B Step 5

C Step 3

D Step 4

💡 Hint

Look at the Command and API Request Sent columns in the execution_table.

If you omit the namespace flag, which namespace does 'kubectl get pods' use?

A all namespaces

B kube-system

C default

D node namespace

💡 Hint

See step 1 and step 4 commands and their API requests in the execution_table.

Concept Snapshot

kubectl get [resource] - Lists resources of the specified type.
Default namespace is 'default' unless '-n' or '--namespace' is used.
Use '--all-namespaces' to list resources across all namespaces.
kubectl sends a GET request to the Kubernetes API server.
The API server returns the current state, which kubectl displays.
Example: 'kubectl get pods' lists pods in default namespace.

Full Transcript

The 'kubectl get' command is used to list Kubernetes resources like pods, services, and nodes. When you run 'kubectl get pods', kubectl sends a request to the Kubernetes API server asking for the list of pods in the default namespace. The API server responds with the current list, and kubectl shows it in a table format. You can specify a different namespace with '-n' or '--namespace', or list resources across all namespaces with '--all-namespaces'. Each command sends a specific API request, and kubectl displays the returned data. This process repeats for each resource type you query. The command ends after showing the resource list.

Practice

1. What does the command kubectl get pods do in Kubernetes?

easy

A. Lists all pods in the current namespace

B. Deletes all pods in the cluster

C. Creates a new pod

D. Shows logs of a pod

Solution

1. Step 1: Understand the command structure

   kubectl get is used to list resources, and pods specifies the resource type.

2. Step 2: Interpret the command effect

   The command lists all pods in the current namespace without modifying or deleting anything.

3. Final Answer:

   Lists all pods in the current namespace -> Option A

4. Quick Check:

   kubectl get pods lists pods [OK]

Hint: Remember: 'get' means list resources, not delete or create [OK]

Common Mistakes:

• Confusing 'get' with 'delete' or 'create'
• Thinking it shows logs instead of listing
• Assuming it lists resources cluster-wide by default

2. Which of the following is the correct syntax to list all services in all namespaces using kubectl?

easy

A. kubectl get services -a

B. kubectl get services --all-namespaces

C. kubectl list services --all

D. kubectl show services --all-namespaces

Solution

1. Step 1: Identify the correct command to list services

   kubectl get services is the correct base command to list services.

2. Step 2: Use the correct flag for all namespaces

   The flag --all-namespaces lists resources across all namespaces; -a is not valid here.

3. Final Answer:

   kubectl get services --all-namespaces -> Option B

4. Quick Check:

   Use --all-namespaces to list across namespaces [OK]

Hint: Use full flag --all-namespaces, not short or wrong ones [OK]

Common Mistakes:

• Using incorrect short flag '-a' which is invalid
• Using 'list' or 'show' instead of 'get'
• Forgetting to specify namespaces flag for cluster-wide listing

3. What will be the output of the command kubectl get pods mypod -o wide if mypod exists in the current namespace?

medium

A. An error saying pod not found

B. Only the pod name will be shown

C. Logs of the pod will be displayed

D. Detailed information about the pod including node and IP

Solution

1. Step 1: Understand the command and flags

   kubectl get pods mypod fetches the pod named 'mypod'. The -o wide flag adds extra details like node name and IP.

2. Step 2: Predict the output

   The output will show the pod's name, status, node, IP, and other extended info, not just the name or logs.

3. Final Answer:

   Detailed information about the pod including node and IP -> Option D

4. Quick Check:

   -o wide shows extra pod details [OK]

Hint: Use -o wide to get more pod details in output [OK]

Common Mistakes:

• Expecting only pod name without details
• Confusing output with logs
• Assuming error if pod exists

4. You run kubectl get pod mypod but get the error: error: the server doesn't have a resource type "pod". What is the likely cause?

medium

A. You typed 'pod' instead of 'pods' for resource type

B. The pod 'mypod' does not exist

C. You need to add --all-namespaces flag

D. kubectl is not installed

Solution

1. Step 1: Analyze the error message

   The error says the server doesn't recognize resource type 'pod'. Kubernetes resource types are plural, e.g., 'pods'.

2. Step 2: Identify the syntax mistake

   The command should use pods not pod. This causes the server to reject the request.

3. Final Answer:

   You typed 'pod' instead of 'pods' for resource type -> Option A

4. Quick Check:

   Resource types are plural like 'pods' [OK]

Hint: Always use plural resource names like 'pods', 'services' [OK]

Common Mistakes:

• Using singular resource names
• Assuming pod doesn't exist causes this error
• Thinking missing flag causes resource type error

5. You want to list all deployments in the namespace 'production' with their labels shown. Which command achieves this?

hard

A. kubectl list deployments -namespace production -labels

B. kubectl get deployment production --labels

C. kubectl get deployments -n production --show-labels

D. kubectl get deployments --namespace=production -o labels

Solution

1. Step 1: Specify the resource and namespace correctly

   kubectl get deployments lists deployments; -n production sets the namespace.

2. Step 2: Use the correct flag to show labels

   The flag --show-labels adds labels column to the output. Other options use incorrect flags or syntax.

3. Final Answer:

   kubectl get deployments -n production --show-labels -> Option C

4. Quick Check:

   Use -n for namespace and --show-labels to display labels [OK]

Hint: Use -n for namespace and --show-labels to see labels [OK]

Common Mistakes:

• Using singular 'deployment' instead of 'deployments'
• Wrong flags like '--labels' or '-labels'
• Using 'list' instead of 'get'