Using Redis in Docker containers
Redis is one of the most popular Docker images. The key-value store makes it possible to save data from Docker containers. If you want to take advantage of this feature, you can connect Redis and Docker in the terminal. Keep reading to find out how.
Requirements for using Redis
After installing Docker on a Linux server, people often ask themselves where they can save data from Docker containers. Redis is a NoSQL database that offers an ideal solution, thanks to its lightning-fast performance. Before you connect Redis and Docker, make sure that the following requirements are met:
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Running Redis in a Docker container
The official Redis image is one of the top three most popular Docker images. It contains the command EXPOSE 6379 (the default Redis port) which makes it automatically available to any linked containers.
To run a Redis instance in a Docker container named my-redis-container, use the command:
sudo docker run --name my-redis-container -d redis
Connecting to Redis running in a Docker container
To connect to a Redis instance from another Docker container, add --link [Redis container name or ID]:redis to that container’s docker run command.
For example, to launch a container named my-redis-application from the official CentOS 7 image and link it to the my-redis-container container, use the command:
sudo docker run --name my-redis-application --link my-redis-container:redis -d centos
To connect to a Redis instance from another Docker container with a command-line interface, link the container and specify the host and port with -h redis -p 6379.
sudo docker run -it --name my-redis-cli --link my-redis-container:redis --rm redis redis-cli -h redis -p 6379
This will connect you to the new container my-redis-cli with a redis-cli connection to the my-redis-container container. Use [Ctrl] + [P] and [Ctrl] + [Q] to exit this container and return to the command line.
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Connect to a Redis container from a remote server
If you wish to connect to a Docker container running Redis from a remote server, you can use Docker’s port forwarding to access the container with the host server’s IP address or domain name.
To use Docker’s port forwarding for Redis, add the flag -p [host port]:6379 to the docker run command.
sudo docker run --name my-redis-container -p 7001:6379 -d redis
You can then switch to another server and access the my-redis-container container with the command:
sudo redis-cli -h [host IP or domain name] -p 7001
For example, if the host server running the Redis Docker container is IP address 192.168.0.1, you can access the Redis container from any server with the command:
sudo redis-cli -h 192.168.0.1 -p 7001
If you are using a firewall, you will need to allow external access to the relevant port(s); otherwise access will be blocked. To do this, simply go into your firewall settings and allow access to the relevant ports.
Loading a Custom redis.conf File
If you have a custom redis.conf file where you’ve already configured Redis, you can load it at container launch by adding the -v flag to the docker run command:
-v [path to custom redis.conf file]:/usr/local/etc/redis/redis.conf
Simply add the file path of your conf-file to the command. For example, to load the customized file with the path /data/myredis/redis.conf, the command is:
sudo docker run --name my-redis-container -v /data/myredis/redis.conf:/usr/local/etc/redis/redis.conf -d redis