Memorystore for Redis caching in GCP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

How does Memorystore for Redis handle failover?

When a primary Redis instance in Memorystore fails, what happens to maintain availability?

A The service deletes all data and creates a new instance from scratch.

B The service requires manual intervention to restart the primary instance.

C The service automatically promotes a replica to primary and redirects traffic without downtime.

D The service pauses all client connections until the primary is fixed.

💡 Hint

Think about how cloud services keep your app running smoothly even if one part breaks.

Memorystore for Redis uses replicas to ensure high availability. If the primary fails, a replica is promoted automatically, minimizing downtime.

❓ Configuration

intermediate

Which Redis version is supported by Memorystore for Redis?

You want to use a specific Redis version with Memorystore. Which version is officially supported?

A Redis 6.x

B Redis 2.8

C Redis 3.0

D Redis 5.0

💡 Hint

Check the latest stable Redis versions supported by cloud providers.

Memorystore for Redis supports Redis 6.x, which includes modern features and security improvements.

❓ security

advanced

What is the best way to secure access to a Memorystore for Redis instance?

Which method ensures only your application can access your Memorystore Redis instance?

A Enable public IP and use Redis AUTH password only.

B Use SSL/TLS encryption without network restrictions.

C Allow all IPs and rely on Redis AUTH password.

D Use VPC Service Controls and private IP with firewall rules restricting access.

💡 Hint

Think about network isolation and limiting who can reach your Redis instance.

Memorystore instances use private IPs inside a VPC. Combining this with firewall rules and VPC Service Controls restricts access securely.

❓ Architecture

advanced

How to design a caching layer with Memorystore for Redis for a global app?

You have users worldwide and want low latency caching. What is the best architecture using Memorystore?

A Deploy one Memorystore instance in a single region and serve all users from it.

B Deploy multiple Memorystore instances in regional GCP zones near users and route traffic accordingly.

C Use Memorystore only in the US region and rely on CDN for caching.

D Deploy Memorystore instances in multiple regions but do not sync data between them.

💡 Hint

Think about placing caches close to users to reduce delay.

Deploying regional Memorystore instances near users reduces latency. Traffic routing ensures users connect to the nearest cache.

✅ Best Practice

expert

What is the recommended approach to handle Redis data persistence in Memorystore?

Memorystore for Redis does not support persistence by default. How should you ensure data durability?

A Use application-level backups by exporting data regularly and storing in Cloud Storage.

B Rely on Memorystore's built-in snapshot backups automatically enabled.

C Enable Redis AOF persistence directly in Memorystore settings.

D Configure Redis to write to local disk on the instance for persistence.

💡 Hint

Memorystore is a managed service with limited persistence options. Think about external backups.

Memorystore does not support persistence or AOF. Best practice is to export data from Redis and store backups externally, such as in Cloud Storage.

Practice

1. What is the main purpose of Memorystore for Redis in Google Cloud?

easy

A. To run virtual machines

B. To permanently store large files

C. To temporarily store data to speed up applications

D. To manage user authentication

Solution

1. Step 1: Understand Memorystore for Redis role

   Memorystore for Redis is designed to cache data temporarily to improve app speed.

2. Step 2: Compare options with purpose

   Options A, B, and D describe unrelated services or functions.

3. Final Answer:

   To temporarily store data to speed up applications -> Option C

4. Quick Check:

   Memorystore caches data = C [OK]

Hint: Memorystore caches data temporarily to speed apps [OK]

Common Mistakes:

• Confusing caching with permanent storage
• Thinking it manages VMs or authentication
• Assuming it stores large files permanently

2. Which of the following is the correct command snippet to create a Memorystore Redis instance with 1 GB memory in region us-central1?

easy

A. gcloud redis create instance my-redis --memory=1GB --region=us-central1

B. gcloud redis instances create my-redis --size=1 --region=us-central1

C. gcloud redis instances create my-redis --memory=1GB --zone=us-central1-a

D. gcloud redis instances new my-redis --size=1GB --region=us-central1

Solution

1. Step 1: Recall correct gcloud command syntax

   The correct command uses 'gcloud redis instances create' with '--size' in GB and '--region'.

2. Step 2: Check each option for syntax errors

   gcloud redis instances create my-redis --size=1 --region=us-central1 matches correct syntax. Options A, C, and D use wrong flags or commands.

3. Final Answer:

   gcloud redis instances create my-redis --size=1 --region=us-central1 -> Option B

4. Quick Check:

   Correct gcloud create syntax = B [OK]

Hint: Use 'gcloud redis instances create' with --size and --region [OK]

Common Mistakes:

• Using --memory instead of --size
• Using 'create instance' instead of 'instances create'
• Specifying zone instead of region

3. Given this Python code snippet using Redis client connected to Memorystore, what will be printed?

import redis
client = redis.Redis(host='10.0.0.5', port=6379)
client.set('color', 'blue')
print(client.get('color'))

medium

A. None

B. 'blue'

C. blue

D. b'blue'

Solution

1. Step 1: Understand Redis get returns bytes

   Redis client returns values as bytes, so 'client.get' returns b'blue'.

2. Step 2: Check print output

   Printing bytes shows with b'' prefix, so output is b'blue'.

3. Final Answer:

   b'blue' -> Option D

4. Quick Check:

   Redis get returns bytes = b'blue' [OK]

Hint: Redis get returns bytes, not string [OK]

Common Mistakes:

• Expecting plain string instead of bytes
• Confusing Redis set/get syntax
• Assuming None if key exists

4. You created a Memorystore Redis instance but your app cannot connect. Which is the most likely cause?

medium

A. The Redis instance is in a different VPC network than the app

B. The Redis instance size is too small

C. The Redis instance region is the same as the app

D. The Redis instance is running the wrong Redis version

Solution

1. Step 1: Identify common connectivity issues

   Memorystore requires the app and Redis instance to be in the same VPC or connected networks.

2. Step 2: Evaluate options

   The Redis instance is in a different VPC network than the app correctly identifies network mismatch causing connection failure. Size, region, or version mismatches do not block connection.

3. Final Answer:

   The Redis instance is in a different VPC network than the app -> Option A

4. Quick Check:

   Network mismatch blocks connection = A [OK]

Hint: Check VPC network match for app and Redis [OK]

Common Mistakes:

• Blaming size or region for connection failure
• Ignoring network setup
• Assuming version mismatch blocks connection

5. You want to reduce database load by caching user session data using Memorystore for Redis. Which approach is best to ensure sessions expire automatically after 30 minutes?

hard

A. Set a TTL (time-to-live) of 1800 seconds on each session key when storing it

B. Manually delete session keys every 30 minutes using a cron job

C. Use a Redis instance with a 30-minute auto-shutdown setting

D. Store sessions without expiration and rely on database cleanup

Solution

1. Step 1: Understand session expiration in Redis

   Redis supports TTL on keys to expire them automatically after a set time.

2. Step 2: Evaluate options for automatic expiration

   Set a TTL (time-to-live) of 1800 seconds on each session key when storing it uses TTL correctly. Manually delete session keys every 30 minutes using a cron job is manual and error-prone. Use a Redis instance with a 30-minute auto-shutdown setting is invalid Redis feature. Store sessions without expiration and rely on database cleanup does not expire sessions.

3. Final Answer:

   Set a TTL (time-to-live) of 1800 seconds on each session key when storing it -> Option A

4. Quick Check:

   Use TTL for auto-expire sessions = D [OK]

Hint: Use TTL on keys for automatic expiration [OK]

Common Mistakes:

• Relying on manual deletion
• Expecting Redis instance to auto-shutdown
• Not setting expiration causing stale sessions