Recreate update strategy in Kubernetes - Step-by-Step Execution

Process Flow - Recreate update strategy

Start Deployment

↓

Delete all old Pods

↓

Wait for all old Pods to terminate

↓

Create new Pods

↓

Wait for new Pods to be Ready

↓

Deployment Complete

The Recreate update strategy deletes all old pods before creating new ones, ensuring no overlap between old and new versions.

Execution Sample

Kubernetes

apiVersion: apps/v1
kind: Deployment
metadata:
  name: example-deploy
spec:
  strategy:
    type: Recreate

This YAML snippet defines a Deployment using the Recreate update strategy to replace pods.

Process Table

Step	Action	Old Pods State	New Pods State	Deployment Status
1	Start Deployment	3 Running	0	In Progress
2	Delete all old Pods	3 Terminating	0	In Progress
3	Wait for old Pods to terminate	0	0	In Progress
4	Create new Pods	0	3 Pending	In Progress
5	New Pods become Ready	0	3 Running	Complete

💡 All old pods terminated and new pods are running, deployment complete.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
Old Pods	3 Running	3 Terminating	0	0	0
New Pods	0	0	0	3 Pending	3 Running
Deployment Status	Not Started	In Progress	In Progress	In Progress	Complete

Key Moments - 2 Insights

Why are all old pods deleted before new pods are created?

Because the Recreate strategy ensures no overlap between old and new pods to avoid conflicts, as shown in execution_table steps 2 and 4.

What happens if new pods fail to become ready after old pods are deleted?

Deployment will be stuck waiting at step 5, since the strategy waits for new pods to be ready before completing.

Visual Quiz - 3 Questions

Look at the execution table, what is the state of old pods at step 3?

A 3 pods running

B 0 pods running

C 3 pods terminating

D 0 pods pending

💡 Hint

Refer to the 'Old Pods State' column at step 3 in the execution_table.

At which step do new pods start to be created?

A Step 2

B Step 3

C Step 4

D Step 5

💡 Hint

Check the 'Action' column for when new pods are created in the execution_table.

If the strategy was changed to RollingUpdate, how would the execution_table change?

A Old and new pods would run simultaneously during update

B All old pods would be deleted before new pods start

C New pods would never be created

D Deployment would complete immediately

💡 Hint

Recreate deletes old pods first; RollingUpdate allows overlap, so see difference in pod states.

Concept Snapshot

Recreate update strategy in Kubernetes:
- Deletes all old pods before creating new ones
- Ensures no overlap between old and new pods
- Deployment waits for old pods termination before new pods start
- Simple but causes downtime during update
- Defined in Deployment spec under strategy.type = Recreate

Full Transcript

The Recreate update strategy in Kubernetes replaces all old pods by first deleting them all, then creating new pods. This means there is downtime because no pods run during the switch. The deployment process starts by deleting old pods, waits for them to terminate, then creates new pods and waits for them to be ready before marking deployment complete. This strategy is simple and ensures no overlap between old and new versions, but causes downtime during updates.