Deployment status and history in Kubernetes - Step-by-Step Execution

Process Flow - Deployment status and history

Create Deployment

↓

Kubernetes Controller creates Pods

↓

Pods start running

↓

Check Deployment Status

↓

View Deployment History

↓

Update Deployment (optional)

↓

New ReplicaSet created

↓

Old ReplicaSet scaled down

↓

Deployment status updated

This flow shows how a Kubernetes Deployment is created, how pods are managed, how status is checked, and how history is tracked through ReplicaSets.

Execution Sample

Kubernetes

kubectl create deployment nginx --image=nginx
kubectl rollout status deployment/nginx
kubectl rollout history deployment/nginx
kubectl set image deployment/nginx nginx=nginx:1.19
kubectl rollout status deployment/nginx

This sequence creates an nginx deployment, checks its status, views its history, updates the image, and checks status again.

Process Table

Step	Command	Action	Result/Output
1	kubectl create deployment nginx --image=nginx	Create deployment named nginx with nginx image	deployment.apps/nginx created
2	kubectl rollout status deployment/nginx	Check rollout status of nginx deployment	deployment "nginx" successfully rolled out
3	kubectl rollout history deployment/nginx	View rollout history of nginx deployment	REVISION CHANGE-CAUSE 1 <none>
4	kubectl set image deployment/nginx nginx=nginx:1.19	Update nginx container image to version 1.19	deployment.apps/nginx image updated
5	kubectl rollout status deployment/nginx	Check rollout status after update	deployment "nginx" successfully rolled out
6	kubectl rollout history deployment/nginx	View updated rollout history	REVISION CHANGE-CAUSE 1 <none> 2 kubectl set image deployment/nginx nginx=nginx:1.19
7	kubectl rollout undo deployment/nginx	Rollback to previous revision	deployment.apps/nginx rolled back
8	kubectl rollout status deployment/nginx	Check rollout status after rollback	deployment "nginx" successfully rolled out

💡 Deployment is successfully rolled out or rolled back, no further updates.

Status Tracker

Variable	Start	After Step 1	After Step 4	After Step 7	Final
Deployment Image	none	nginx:latest	nginx:1.19	nginx:latest	nginx:latest
Deployment Revision	none	1	2	1	1
Deployment Status	none	Rolled out	Rolled out	Rolled out	Rolled out

Key Moments - 3 Insights

Why does the rollout history show multiple revisions?

Each deployment update creates a new revision tracked in rollout history, as seen in steps 3 and 6 where revision 1 and 2 appear.

What does 'kubectl rollout status' tell us?

It shows if the deployment is successfully rolled out or still updating, as shown in steps 2, 5, and 8 where it confirms success.

How does rollback affect the deployment image?

Rollback restores the deployment image to the previous revision's image, shown in variable_tracker where image changes back to nginx:latest after step 7.

Visual Quiz - 3 Questions

Look at the execution table at step 4. What change happens to the deployment?

A The deployment is deleted

B The deployment image is updated to nginx:1.19

C The deployment is scaled to zero pods

D The deployment status is checked

💡 Hint

Refer to the 'Action' and 'Result/Output' columns at step 4 in the execution table.

At which step does the deployment rollback occur?

A Step 5

B Step 3

C Step 7

D Step 2

💡 Hint

Look for the command 'kubectl rollout undo' in the execution table.

According to the variable tracker, what is the deployment image after step 7?

A nginx:latest

B nginx:1.19

C none

D nginx:1.20

💡 Hint

Check the 'Deployment Image' row under 'After Step 7' in the variable tracker.

Concept Snapshot

kubectl create deployment NAME --image=IMAGE  # Create deployment
kubectl rollout status deployment/NAME       # Check rollout status
kubectl rollout history deployment/NAME      # View deployment revisions
kubectl set image deployment/NAME CONTAINER=IMAGE  # Update image
kubectl rollout undo deployment/NAME          # Rollback to previous revision
Deployment status shows if pods are running as expected; history tracks changes.

Full Transcript

This visual execution traces Kubernetes deployment status and history commands. First, a deployment named nginx is created with the nginx image. The rollout status command confirms the deployment is running successfully. Rollout history shows the initial revision. Then, the deployment image is updated to nginx:1.19, creating a new revision. Status is checked again to confirm success. History now shows two revisions. A rollback command restores the deployment to the previous image and revision. The final status confirms the rollback succeeded. Variables tracked include deployment image, revision number, and status, showing how they change after each command. Key moments clarify why multiple revisions appear, what rollout status means, and how rollback affects the deployment image. Quiz questions test understanding of update, rollback, and variable states referencing the execution table and variable tracker.