Failover manual process in Redis - Mini Project: Build & Apply

Manual Failover Process in Redis

📖 Scenario: You are managing a Redis setup with one master and two replicas. Sometimes the master server can go down, and you need to manually promote a replica to become the new master to keep your application running smoothly.

🎯 Goal: Learn how to perform a manual failover in Redis by promoting a replica to master and reconfiguring other replicas to follow the new master.

📋 What You'll Learn

Create a list of Redis nodes with their roles and IP addresses

Define the current master node IP

Write commands to promote a replica to master manually

Update other replicas to follow the new master

💡 Why This Matters

🌍 Real World

In real Redis deployments, manual failover is sometimes necessary when automatic failover fails or is not configured. This project simulates the commands and steps needed to perform manual failover.

💼 Career

Understanding manual failover helps database administrators and DevOps engineers maintain high availability and reliability of Redis services in production environments.

1

Setup Redis nodes list

Create a list called redis_nodes containing dictionaries for three Redis nodes with these exact entries: {'ip': '192.168.1.10', 'role': 'master'}, {'ip': '192.168.1.11', 'role': 'replica'}, and {'ip': '192.168.1.12', 'role': 'replica'}.

Redis

# Create the redis_nodes list with three nodes
# Your code here

Need a hint?

Use a Python list with dictionaries for each Redis node.

2

Define current master IP

Create a variable called current_master_ip and set it to the string '192.168.1.10' to represent the current master node IP.

Redis

redis_nodes = [
    {'ip': '192.168.1.10', 'role': 'master'},
    {'ip': '192.168.1.11', 'role': 'replica'},
    {'ip': '192.168.1.12', 'role': 'replica'}
]
# Define the current master IP
# Your code here

Need a hint?

Assign the IP of the master node to current_master_ip.

3

Promote a replica to master

Write a command string called promote_command that uses the Redis CLI command redis-cli -h 192.168.1.11 SLAVEOF NO ONE to promote the replica at IP 192.168.1.11 to master.

Redis

redis_nodes = [
    {'ip': '192.168.1.10', 'role': 'master'},
    {'ip': '192.168.1.11', 'role': 'replica'},
    {'ip': '192.168.1.12', 'role': 'replica'}
]

current_master_ip = '192.168.1.10'
# Write the promote_command string to promote replica 192.168.1.11
# Your code here

Need a hint?

Use the exact Redis CLI command string to promote the replica.

4

Reconfigure other replicas to follow new master

Create a list called replica_follow_commands containing the Redis CLI commands to make the replica at IP 192.168.1.12 follow the new master at IP 192.168.1.11. The command should be redis-cli -h 192.168.1.12 SLAVEOF 192.168.1.11 6379.

Redis

redis_nodes = [
    {'ip': '192.168.1.10', 'role': 'master'},
    {'ip': '192.168.1.11', 'role': 'replica'},
    {'ip': '192.168.1.12', 'role': 'replica'}
]

current_master_ip = '192.168.1.10'

promote_command = 'redis-cli -h 192.168.1.11 SLAVEOF NO ONE'
# Create replica_follow_commands list with command for 192.168.1.12 to follow 192.168.1.11
# Your code here

Need a hint?

Put the exact command string inside a list called replica_follow_commands.