Skip to main content

Understanding the Redis Configuration File

In this lesson, we will dive deep into the Redis configuration file (redis.conf). You will learn how to locate it, read it, and customize it to suit your development or production needs.

What is redis.conf?​

The redis.conf file is the primary configuration file for Redis. It determines how Redis behaves at runtime, including settings for:

  • Memory usage
  • Persistence
  • Network bindings
  • Security
  • Logging
  • Replication and clustering

Redis loads this file when the server starts, unless you explicitly override configuration options via command-line arguments or environment variables.

You can typically find redis.conf in locations like /etc/redis/, /usr/local/etc/redis/, or the root of the Redis source directory. If you installed Redis via a package manager, use find / -name redis.conf to locate it.

Key Sections in redis.conf​

1. General Options​

When to enable: Use daemonize yes for production environments so Redis runs in the background.

When to disable: In development, disabling makes logs appear in the terminal.

2. Network Settings​

Best practice: Always use bind 127.0.0.1 and protected-mode yes unless you have strict firewall rules.

3. Logging and Debugging​

When to use debug: While debugging or troubleshooting.

When to use notice or warning: In production to reduce noise.

4. Persistence Options​

Use both AOF and RDB: for a balance of speed and durability.

5. Memory Management​

When to set maxmemory: Always in production to prevent server crashes.

Eviction choice: Use allkeys-lru for caching workloads.

6. Security Settings​

When to require password: Always if Redis is accessible over a network.

When to rename commands: To protect admin commands like FLUSHALL.

7. Replication and Clustering​

When to use replication: For high availability and backups.

When to enable clustering: For large-scale, distributed setups.

Customizing the Configuration​

You can launch Redis with a custom configuration file like this:

redis-server /path/to/your/redis.conf

Or override options inline:

redis-server --port 6380 --maxmemory 128mb --requirepass secret123

Some config changes can be made at runtime using CONFIG SET:

redis-cli CONFIG SET maxmemory 512mb

However, not all options are runtime-configurable. Changes made via CLI are not persistent unless saved with:

redis-cli CONFIG REWRITE
Best Practices
  • Do not expose Redis to public networks without proper authentication and firewalls.
  • Use both RDB and AOF for a balance of durability and performance.
  • Tune snapshot intervals (save) and AOF fsync policy (appendfsync) according to durability needs.
  • Set reasonable memory limits to avoid OOM crashes.
  • Regularly monitor logs and performance using INFO, MONITOR, and SLOWLOG.
  • Always back up your configuration before making changes.

Hands-On Task​

  1. Locate the default redis.conf on your system (try redis-server --help or check /etc/redis/).
  2. Change the port from 6379 to 6380, restart the server, and test using redis-cli -p 6380.
  3. Enable AOF, make some writes, then inspect the contents of appendonly.aof.
  4. Try using CONFIG SET maxmemory 100mb, then confirm with CONFIG GET maxmemory.