Firewall Configuration

To allow Redis traffic through the firewall, add a rule for port 6379:

iptables -I INPUT -p tcp --dport 6379 -j ACCEPT
service iptables save

Installation Steps

1. Navigate to the download directory:

cd /usr/local/src

3. Download the Redis source package (example version 3.2.9):

wget http://download.redis.io/releases/redis-3.2.9.tar.gz

5. Extract the archive:

tar xzf redis-3.2.9.tar.gz

7. Enter the source directory:

cd redis-3.2.9

9. Create the installation directory structure:

mkdir -p /opt/redis/etc

11. Compile Redis:

make

13. Install Redis to the target directory:

cd src
make install PREFIX=/opt/redis

15. Copy the configuratoin file:

cp redis.conf /opt/redis/etc

17. Configure Redis to run in the background:

vim /opt/redis/etc/redis.conf

Set daemonize yes in the configuration file.

20. Start the Redis server:

/opt/redis/bin/redis-server /opt/redis/etc/redis.conf

22. Enable startup on boot:

vim /etc/rc.local

Add the following line to the file:

/opt/redis/bin/redis-server /opt/redis/etc/redis.conf

Configuration File Parameters

• background_execution: Set to yes to run Redis in the background.
• listen_ip: Specify the IP address Redis should bind to (e.g., 127.0.0.1 for local access).
• listen_port: Default port is 6379.
• connection_timeout: Time in seconds before a client connection times out.
• log_level: Log verbosity (debug, verbose, notice, warning). Use notice in production.
• log_file: Path to the log file (e.g., /var/log/redis.log).
• database_count: Number of databases (default: 1).
• snapshot_schedule: Frequency of database snapshots (e.g., save 900 1 saves every 15 minutes if 1 key changed).
• rdb_compression: Enable compression for RDB snapshots.
• rdb_filename: Name of the RDB snapshot file (default: dump.rdb).
• snapshot_dir: Directory for RDB snapshots.
• replica_of: Configure as a replica of another Redis instance.
• master_password: Password for the master server (if required).
• client_password: Password required for client connections.
• max_clients: Maximum number of concurrent clients.
• max_memory: Maximum memory Redis can use.
• append_only: Enable AOF (Append-Only File) mode for persistence.
• aof_sync_frequency: Frequency of AOF file synchronization.
• vm_enabled: Enable virtual memory support (deprecated in recent versions).
• vm_swap_file: Path to the virtual memory swap file.
• vm_max_memory: Maximum physical memory for virtual memory.
• vm_page_size: Size of virtual memory pages.
• vm_pages: Total number of pages in the swap file.
• vm_max_threads: Number of threads for VM I/O operations.

Redis Tools

• redis-benchmark: Performance testing tool.
• redis-check-aof: AOF log integrity checker.
• redis-check-dump: RDB snapshot integrity checker.
• redis-cli: Command-line client.
• redis-server: Redis server process.

Startup Warning Fixes

Warning 1: overcommit_memory is set to 0

This warning occurs when the kernel’s memory overcommit policy is too restrictive. To fix:

1. Permanently set vm.overcommit_memory = 1:

echo "vm.overcommit_memory=1" > /etc/sysctl.conf
sysctl -p

3. Temporarily apply the setting (no reboot needed):

echo 1 > /proc/sys/vm/overcommit_memory

Note: Redis forks a child process during snapshots. Setting vm.overcommit_memory = 1 allows the kernel to allocate memory evenif physical memory is low, preventing crashes.

Warning 2: TCP backlog setting cannot be enforced

This warning occurs when somaxconn is lower than the desired backlog. Fix by setting somaxconn to 511:

echo 511 > /proc/sys/net/core/somaxconn