Recreate update strategy in Kubernetes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Recreate update strategy in Kubernetes?

It is a deployment method where all existing pods are stopped before new pods are started. This ensures only one version runs at a time.

intermediate

How does the Recreate strategy differ from RollingUpdate in Kubernetes?

Recreate stops all old pods before starting new ones, causing downtime. RollingUpdate replaces pods gradually, keeping the app available.

beginner

When is it best to use the Recreate update strategy?

Use it when your app cannot run multiple versions at once or when you want a simple update with guaranteed clean start.

beginner

Show the YAML snippet to set Recreate update strategy in a Deployment.

spec: strategy: type: Recreate

beginner

What is a possible downside of using the Recreate update strategy?

It causes downtime because the old pods stop before new pods start, so the app is temporarily unavailable.

What happens first in the Recreate update strategy?

A Pods are updated one by one

B New pods start alongside old pods

C Pods are scaled up before scaling down

D All old pods are terminated

In Recreate, Kubernetes stops all old pods before starting new ones.

Which update strategy avoids downtime by updating pods gradually?

A RollingUpdate

B Recreate

C BlueGreen

D Canary

RollingUpdate updates pods gradually to keep the app available.

How do you specify the Recreate strategy in a Deployment YAML?

A strategy: type: Recreate

B strategy: type: RollingUpdate

C updateStrategy: Recreate

D deploymentStrategy: recreate

The correct YAML field is 'strategy.type: Recreate'.

What is a main disadvantage of the Recreate update strategy?

A Complex configuration

B Causes downtime during update

C Does not update pods

D Requires multiple versions running

Recreate causes downtime because old pods stop before new pods start.

When should you choose Recreate over RollingUpdate?

A When you want gradual updates

B When zero downtime is critical

C When app cannot run multiple versions simultaneously

D When using StatefulSets

Recreate is good when the app cannot run multiple versions at once.

Explain how the Recreate update strategy works in Kubernetes and when it is useful.

Think about how pods are replaced and app availability.

Describe the YAML configuration needed to set the Recreate update strategy in a Deployment.

Look for the 'strategy' field in Deployment YAML.

Practice

1. What does the Recreate update strategy do in Kubernetes?

easy

A. Deletes old pods before creating new ones, causing downtime

B. Creates new pods first, then deletes old pods to avoid downtime

C. Updates pods one by one without deleting any

D. Scales pods up and down simultaneously during update

Solution

1. Step 1: Understand the Recreate strategy behavior

   The Recreate strategy deletes all old pods before starting new pods, which causes downtime.

2. Step 2: Compare with other strategies

   Other strategies like RollingUpdate create new pods before deleting old ones to avoid downtime, unlike Recreate.

3. Final Answer:

   Deletes old pods before creating new ones, causing downtime -> Option A

4. Quick Check:

   Recreate = delete old pods first [OK]

Hint: Recreate means delete old pods first, then create new [OK]

Common Mistakes:

• Confusing Recreate with RollingUpdate
• Thinking Recreate avoids downtime
• Assuming pods update one by one

2. Which YAML snippet correctly sets the update strategy to Recreate in a Deployment?

easy

A. strategy:\n type: RollingUpdate

B. strategy:\n type: Recreate

C. updateStrategy:\n type: Recreate

D. deploymentStrategy:\n type: Recreate

Solution

1. Step 1: Identify correct field name for update strategy

   The correct field under Deployment spec is strategy with a nested type.

2. Step 2: Check correct value for Recreate

   The value must be exactly Recreate to set that strategy.

3. Final Answer:

   strategy:\n type: Recreate -> Option B

4. Quick Check:

   strategy.type = Recreate [OK]

Hint: Use 'strategy.type: Recreate' exactly in Deployment spec [OK]

Common Mistakes:

• Using wrong field names like updateStrategy or deploymentStrategy
• Setting type to RollingUpdate instead of Recreate
• Incorrect indentation or YAML syntax

3. Given this Deployment with strategy.type: Recreate, what happens when you update the container image?

medium

A. Pods update one by one without downtime

B. New pods start first, then old pods terminate, no downtime

C. All old pods are terminated before new pods start, causing downtime

D. Pods scale up and down simultaneously

Solution

1. Step 1: Understand Recreate update behavior on image change

   When the image changes, Recreate deletes all old pods before creating new pods.

2. Step 2: Recognize downtime impact

   Because old pods are deleted first, there is downtime until new pods are ready.

3. Final Answer:

   All old pods are terminated before new pods start, causing downtime -> Option C

4. Quick Check:

   Recreate update = downtime during pod replacement [OK]

Hint: Recreate deletes old pods first, causing downtime on update [OK]

Common Mistakes:

• Assuming pods update without downtime
• Confusing with RollingUpdate behavior
• Thinking pods update one by one

4. You set strategy.type: Recreate but notice pods are not deleted before new ones start. What is the likely issue?

medium

A. The Deployment has maxUnavailable set to 0, causing RollingUpdate behavior

B. The Deployment is using StatefulSet instead of Deployment

C. The pods have readinessProbe misconfigured

D. The strategy type is misspelled or incorrectly set

Solution

1. Step 1: Check strategy type correctness

   If pods are not deleted first, the strategy type may be misspelled or set incorrectly, so Kubernetes defaults to RollingUpdate.

2. Step 2: Rule out other causes

   maxUnavailable affects RollingUpdate, readinessProbe affects pod readiness, and StatefulSet is a different resource type.

3. Final Answer:

   The strategy type is misspelled or incorrectly set -> Option D

4. Quick Check:

   Misspelled strategy.type causes default RollingUpdate [OK]

Hint: Check exact spelling of strategy.type: Recreate [OK]

Common Mistakes:

• Assuming maxUnavailable affects Recreate
• Ignoring YAML syntax errors
• Confusing Deployment with StatefulSet

5. You have an app that cannot run multiple versions simultaneously. How do you configure the Deployment update strategy to avoid version conflicts?

hard

A. Set strategy.type: Recreate to delete old pods before new ones

B. Set strategy.type: RollingUpdate with maxSurge=1

C. Use kubectl rollout restart without changing strategy

D. Set strategy.type: BlueGreen for zero downtime

Solution

1. Step 1: Identify app requirement

   The app cannot run multiple versions at the same time, so pods must not overlap.

2. Step 2: Choose update strategy

   Recreate deletes old pods before creating new ones, ensuring no version overlap.

3. Step 3: Rule out other options

   RollingUpdate allows overlapping versions, kubectl restart doesn't change strategy, BlueGreen is not a built-in Kubernetes strategy.

4. Final Answer:

   Set strategy.type: Recreate to delete old pods before new ones -> Option A

5. Quick Check:

   App needs no overlap = use Recreate [OK]

Hint: Use Recreate strategy to avoid running multiple versions [OK]

Common Mistakes:

• Choosing RollingUpdate which allows overlap
• Thinking kubectl restart changes update strategy
• Assuming BlueGreen is a native Kubernetes strategy