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How to use Redis with Docker?

 Sunday, 16 March 2025
REDIS

Redis is a popular in-memory data structure store, used as a database, cache, and message broker. Docker, a containerization platform, makes deploying and managing Redis instances significantly easier. This guide walks you through everything you need to know to effectively use Redis with Docker, covering setup, data persistence, configuration, and best practices.

Why Use Redis with Docker?

  • Simplified Deployment: Docker eliminates dependency conflicts and ensures consistent environments across different machines.
  • Scalability: Easily scale Redis instances up or down based on your application's needs.
  • Isolation: Docker containers isolate Redis from the host system, improving security and preventing conflicts with other applications.
  • Reproducibility: Docker images ensure that your Redis setup is reproducible, making it easy to recreate the same environment in different locations.
  • Version Control: Manage Redis versions effectively using Docker images. Upgrade or downgrade seamlessly.

Prerequisites

Before you begin, make sure you have the following installed:

  • Docker: Install Docker Desktop (for Windows and macOS) or Docker Engine (for Linux). Follow the official Docker installation instructions for your operating system.
  • Docker Compose (Optional): While not strictly required, Docker Compose simplifies multi-container applications. It's recommended for more complex setups.

Running Redis in a Docker Container

The simplest way to run Redis in Docker is by pulling the official Redis image from Docker Hub and running it.

1. Pulling the Redis Image

Open your terminal and run the following command to download the latest stable version of the Redis image:

docker pull redis:latest

You can also pull a specific version, for example, Redis 7:

docker pull redis:7

2. Running the Redis Container

Once the image is downloaded, you can start a Redis container using the docker run command:

docker run --name my-redis -d -p 6379:6379 redis:latest

Let's break down this command:

  • docker run: Creates and starts a container.
  • --name my-redis: Assigns the name "my-redis" to the container. It makes the container easier to reference in other commands.
  • -d: Runs the container in detached mode (background).
  • -p 6379:6379: Maps port 6379 on your host machine to port 6379 inside the container (the default Redis port). This allows you to connect to Redis from your host.
  • redis:latest: Specifies the image to use (the Redis image we pulled earlier).

3. Verifying Redis is Running

You can check if the Redis container is running using the docker ps command:

docker ps

You should see the "my-redis" container listed, indicating it's running.

4. Connecting to the Redis Server

You can connect to the Redis server using the redis-cli command-line interface. If you don't have redis-cli installed locally, you can run it within a Docker container using docker exec:

docker exec -it my-redis redis-cli

This command does the following:

  • docker exec: Executes a command in a running container.
  • -it: Allocates a pseudo-TTY connected to the container's STDIN and keeps STDIN open even if not attached.
  • my-redis: Specifies the container in which to run the command.
  • redis-cli: The command to execute (the Redis command-line client).

Once connected, you can run Redis commands, such as:

set mykey myvalue
get mykey

This will set a key called "mykey" to the value "myvalue" and then retrieve it. You should see "myvalue" printed as the result.

Data Persistence with Volumes

By default, data stored in a Docker container is lost when the container is stopped or removed. To persist Redis data, you need to use Docker volumes. Volumes provide a way to store data outside of the container's file system on the host machine.

1. Creating a Volume

Create a Docker volume using the docker volume create command:

docker volume create redis-data

2. Running the Redis Container with a Volume

Modify the docker run command to mount the volume to the Redis data directory inside the container (/data):

docker run --name my-redis -d -p 6379:6379 -v redis-data:/data redis:latest

Now, all data stored in Redis will be persisted in the redis-data volume on your host machine, even if the container is stopped or removed. When you restart the container, it will automatically load the data from the volume.

3. Inspecting Volumes

You can use the following to verify that the data is saved within a container

docker volume inspect redis-data

Configuring Redis in Docker

You can customize the Redis configuration by providing a custom redis.conf file.

1. Creating a Custom Configuration File

Create a file named redis.conf with your desired configurations. For example, to change the default port to 7000, add the following to redis.conf:

port 7000

You can configure many other settings in redis.conf, such as memory limits, persistence options, and security settings. Refer to the official Redis documentation for details.

2. Mounting the Configuration File

Mount the redis.conf file to the /usr/local/etc/redis/redis.conf directory inside the container using the -v option in the docker run command:

docker run --name my-redis -d -p 7000:7000 -v $(pwd)/redis.conf:/usr/local/etc/redis/redis.conf redis:latest --requirepass mysecretpassword

Pay attention to the changes above: the port is now forwarded to 7000, instead of the defaut 6379, and the configuration requires a password to connect.

In addition to configuring, you can use command-line to perform same tasks like above with the redis-server

docker run --name my-redis -d -p 7000:7000 redis:latest redis-server --requirepass mysecretpassword --port 7000

Note, there may be error of missing permission of writing configuration when running above line.

Now the Redis instance within the Docker container will use the configurations you defined in redis.conf. The default configs won't load until we manually config and save in local file then mount the data.

Using Docker Compose

Docker Compose is a tool for defining and running multi-container Docker applications. It's particularly useful for managing Redis and other services in a more organized way.

1. Creating a docker-compose.yml File

Create a file named docker-compose.yml with the following content:

version: "3.8"
services:
redis:
image: redis:latest
container_name: my-redis
ports:
- "6379:6379"
volumes:
- redis-data:/data
restart: always

volumes:
redis-data:

This file defines a service named "redis" based on the redis:latest image. It also maps port 6379, mounts the redis-data volume, and sets the restart policy to "always", ensuring the container restarts if it crashes.

2. Starting the Application

Navigate to the directory containing the docker-compose.yml file and run the following command:

docker-compose up -d

This will start the Redis container in detached mode based on the configuration in docker-compose.yml. The docker-compose up -d command will start all containers and networks mentioned in your docker-compose.yml file

3. Stopping the Application

To stop the application, run:

docker-compose down

This will stop and remove the containers defined in docker-compose.yml.

Security Considerations

  • Set a Password: Protect your Redis instance by setting a password using the requirepass configuration option in redis.conf or via the command line when running redis-server.
  • Firewall Rules: Ensure that only authorized hosts can connect to your Redis server by configuring appropriate firewall rules.
  • Limit Access: Avoid exposing your Redis server to the internet unless absolutely necessary. If you need to expose it, use a secure VPN or firewall to limit access.
  • Avoid root User: Dont expose yourself by binding container directly to your computer's port. Configure firewall such as ufw
  • Regularly Update: Keep both the Redis image and your underlying Docker installation updated with the latest security patches.
  • Production ready password Instead of manually adding, using the system environment is recommended.

Best Practices

  • Use Specific Versions: Instead of using latest for the Redis image, specify a specific version to avoid unexpected changes when the image is updated.
  • Monitor Resource Usage: Monitor the CPU and memory usage of your Redis container to ensure it's not being overstressed. You can use Docker's built-in monitoring tools or third-party monitoring solutions.
  • Regular Backups: Implement a backup strategy for your Redis data to protect against data loss.
  • Properly Size Your Instance: Take advantage of metrics by taking proper planning
  • Customize the Redis Docker image by writing your Dockerfile so you have better control.
  • Leverage healthchecks in your containerization layer to determine if your service is operating within the proper SLA

Conclusion

Using Redis with Docker provides a powerful and efficient way to manage and deploy your Redis instances. By leveraging Docker's features, you can easily scale, isolate, and reproduce your Redis environment, leading to more reliable and maintainable applications. Remember to implement data persistence, configure security settings, and follow best practices to ensure the optimal performance and security of your Redis setup.

Docker Containerization Deployment 
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