containers/bitnami/redis

What is Redis?

Redis is an advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs.

redis.io

TLDR

docker run --name redis bitnami/redis

Docker Compose

redis:
  image: bitnami/redis

Get this image

The recommended way to get the Bitnami Redis Docker Image is to pull the prebuilt image from the Docker Hub Registry.

docker pull bitnami/redis:latest

To use a specific version, you can pull a versioned tag. You can view the list of available versions in the Docker Hub Registry.

docker pull bitnami/redis:[TAG]

If you wish, you can also build the image yourself.

git clone https://github.com/bitnami/bitnami-docker-redis.git
cd bitnami-docker-redis
docker build -t bitnami/redis .

Persisting your database

If you remove the container all your data will be lost, and the next time you run the image the database will be reinitialized. To avoid this loss of data, you should mount a volume that will persist even after the container is removed.

Note! If you have already started using your database, follow the steps on backing up and restoring to pull the data from your running container down to your host.

The Redis image exposes a volume at /bitnami/redis/data, you can mount a directory from your host to serve as the data store. If the directory you mount is empty, the database will be initialized.

docker run -v /path/to/data:/bitnami/redis/data bitnami/redis

or using Docker Compose:

redis:
  image: bitnami/redis
  volumes:
    - /path/to/data:/bitnami/redis/data

Linking

If you want to connect to your Redis server inside another container, you can use the linking system provided by Docker.

Connecting a Redis client container to the Redis server container

Step 1: Run the Redis image with a specific name

The first step is to start our Redis server.

Docker's linking system uses container ids or names to reference containers. We can explicitly specify a name for our Redis server to make it easier to connect to other containers.

docker run --name redis bitnami/redis

Step 2: Run Redis as a client and link to our server

Now that we have our Redis server running, we can create another container that links to it by giving Docker the --link option. This option takes the id or name of the container we want to link it to as well as a hostname to use inside the container, separated by a colon. For example, to have our Redis server accessible in another container with server as it's hostname we would pass --link redis:server to the Docker run command.

The Bitnami Redis Docker Image also ships with a Redis client, but by default it will start a server. To start the client instead, we can override the default command Docker runs by stating a different command to run after the image name.

docker run --rm -it --link redis:server bitnami/redis redis-cli -h server

We started the Redis client passing in the -h option that allows us to specify the hostname of the server, which we set to the hostname we created in the link.

Note! You can also run the Redis client in the same container the server is running in using the Docker exec command.

docker exec -it redis-server redis-cli

Linking with Docker Compose

Step 1: Add a Redis entry in your docker-compose.yml

Copy the snippet below into your docker-compose.yml to add Redis to your application.

redis:
  image: bitnami/redis

Step 2: Link it to another container in your application

Update the definitions for containers you want to access your Redis server from to include a link to the redis entry you added in Step 1.

myapp:
  image: myapp
  links:
    - redis:redis

Inside myapp, use redis as the hostname for the Redis server.

Configuration

Setting the server password on first run

Passing the REDIS_PASSWORD environment variable when running the image for the first time will set the Redis server password to the value of REDIS_PASSWORD.

docker run --name redis -e REDIS_PASSWORD=password123 bitnami/redis

or using Docker Compose:

redis:
  image: bitnami/redis
  environment:
    - REDIS_PASSWORD=password123

Setting up a replication

A replication cluster can easily be setup with the Bitnami Redis Docker Image using the following environment variables:

• REDIS_REPLICATION_MODE: Replication mode. Possible values master/slave (default: none).
• REDIS_MASTER_HOST: Hostname/IP of replication master (parameter available only on slave).
• REDIS_MASTER_PORT: Port of replication master, defaults to 6379 (parameter available only on slave).
• REDIS_MASTER_PASSWORD: Master auth password used by slave to authenticate with the master (default: none).

In a replication cluster you can have one master and zero or more slaves. When replication is enabled writes can occur only on the master while reads can take place on both the master or slaves. For best performance you should limit the reads to the slaves and use the master only for the writes.

Step 1: Create the replication master

The first step is to start the master.

docker run --name redis-master \
  -e REDIS_PASSWORD=masterpassword123 \
  -e REDIS_REPLICATION_MODE=master \
  bitnami/redis

In this command we are configuring the container as the master using the REDIS_REPLICATION_MODE=master parameter. The REDIS_PASSWORD parameter enables authentication on the Redis master.

Step 2: Create the replication slave

Next we start a replication slave container.

docker run --name redis-slave \
  --link redis-master:master \
  -e REDIS_PASSWORD=password123 \
  -e REDIS_MASTER_HOST=master \
  -e REDIS_MASTER_PORT=6379 \
  -e REDIS_MASTER_PASSWORD=masterpassword123 \
  -e REDIS_REPLICATION_MODE=slave \
  bitnami/redis

In this command we are configuring the container as a slave using the REDIS_REPLICATION_MODE=slave parameter. The REDIS_MASTER_HOST and REDIS_MASTER_PORT parameters are used by the slave container to connect to the master. The REDIS_MASTER_PASSWORD specifies the master password allowing the slave to authenticate with the master. The REDIS_PASSWORD parameter enables authentication on the Redis slave.

Using the master docker link alias, the Bitnami Redis Docker image automatically fetches the replication paramaters from the master container, namely:

• REDIS_MASTER_HOST
• REDIS_MASTER_PORT
• REDIS_MASTER_PASSWORD

As a result you can drop all of these parameters from the slave.

docker run --name redis-slave \
  --link redis-master:master \
  -e REDIS_PASSWORD=password123 \
  -e REDIS_REPLICATION_MODE=slave \
  bitnami/redis

With these two commands you now have a two node Redis master-slave replication cluster up and running. When required you can add more slaves to the cluster without any downtime allowing you to scale the cluster horizontally.

If the master goes down you can reconfigure a slave to become a master and begin accepting writes using:

docker exec redis-slave redis-cli -a password123 SLAVEOF NO ONE

Note

: The configuration of the other slaves in the cluster needs to be updated so that they are aware of the new master. This would require you to restart the other slaves with --link redis-slave:master as per our examples.

With Docker Compose the master-slave replication can be setup using:

master:
  image: bitnami/redis
  environment:
    - REDIS_PASSWORD=masterpassword123
    - REDIS_REPLICATION_MODE=master

slave:
  image: bitnami/redis
  links:
    - master:master
  environment:
    - REDIS_PASSWORD=password123
    - REDIS_REPLICATION_MODE=slave

Scale the number of slaves using:

docker-compose scale master=1 slave=3

The above command scales up the number of slaves to 3. You can scale down in the same way.

Note

: You should not scale up/down the number of master nodes. Always have only one master node running.

Command-line options

The simplest way to configure your Redis server is to pass custom command-line options when running the image.

docker run bitnami/redis --maxclients 10

or using Docker Compose:

redis:
  image: bitnami/redis
  command: --maxclients 10

Configuration file

This image looks for configuration in /bitnami/redis/conf. You can mount a volume there with your own configuration, or the default configuration will be copied to your volume if it is empty.

Step 1: Run the Redis image

Run the Redis image, mounting a directory from your host.

docker run --name redis -v /path/to/redis/conf:/bitnami/redis/conf bitnami/redis

or using Docker Compose:

redis:
  image: bitnami/redis
  volumes:
    - /path/to/redis/conf:/bitnami/redis/conf

Step 2: Edit the configuration

Edit the configuration on your host using your favorite editor.

vi /path/to/redis/conf/redis.conf

Step 3: Restart Redis

After changing the configuration, restart your Redis container for changes to take effect.

docker restart redis

or using Docker Compose:

docker-compose restart redis

Further Reading:

• Redis Configuration Documentation

Logging

The Bitnami Redis Docker Image supports two different logging modes: logging to stdout, and logging to a file.

Logging to stdout

The default behavior is to log to stdout, as Docker expects. These will be collected by Docker, converted to JSON and stored in the host, to be accessible via the docker logs command.

docker logs redis

or using Docker Compose:

docker-compose logs redis

This method of logging has the downside of not being easy to manage. Without an easy way to rotate logs, they could grow exponentially and take up large amounts of disk space on your host.

Logging to file

To log to file, run the Redis image, mounting a directory from your host at /bitnami/redis/logs. This will instruct the container to send logs to a redis-server.log file in the mounted volume.

docker run --name redis -v /path/to/redis/logs:/bitnami/redis/logs bitnami/redis

or using Docker Compose:

redis:
  image: bitnami/redis
  volumes:
    - /path/to/redis/logs:/bitnami/redis/logs

To perform operations (e.g. logrotate) on the logs, mount the same directory in a container designed to operate on log files, such as logstash.

Maintenance

Backing up your container

To backup your data, configuration and logs, follow these simple steps:

Step 1: Stop the currently running container

docker stop redis

or using Docker Compose:

docker-compose stop redis

Step 2: Run the backup command

We need to mount two volumes in a container we will use to create the backup: a directory on your host to store the backup in, and the volumes from the container we just stopped so we can access the data.

docker run --rm -v /path/to/backups:/backups --volumes-from redis busybox \
  cp -a /bitnami/redis /backups/latest

or using Docker Compose:

docker run --rm -v /path/to/backups:/backups --volumes-from `docker-compose ps -q redis` busybox \
  cp -a /bitnami/redis /backups/latest

Note! If you only need to backup database data, or configuration, you can change the first argument to cp to /bitnami/redis/data or /bitnami/redis/conf respectively.

Restoring a backup

Restoring a backup is as simple as mounting the backup as volumes in the container.

docker run -v /path/to/backups/latest/data:/bitnami/redis/data \
  -v /path/to/backups/latest/conf:/bitnami/redis/conf \
  -v /path/to/backups/latest/logs:/bitnami/redis/logs \
  bitnami/redis

or using Docker Compose:

redis:
  image: bitnami/redis
  volumes:
    - /path/to/backups/latest/data:/bitnami/redis/data
    - /path/to/backups/latest/conf:/bitnami/redis/conf
    - /path/to/backups/latest/logs:/bitnami/redis/logs

Upgrade this image

Bitnami provides up-to-date versions of Redis, including security patches, soon after they are made upstream. We recommend that you follow these steps to upgrade your container.

Step 1: Get the updated image

docker pull bitnami/redis:latest

or if you're using Docker Compose, update the value of the image property to bitnami/redis:latest.

Step 2: Stop and backup the currently running container

Before continuing, you should backup your container's data, configuration and logs.

Follow the steps on creating a backup.

Step 3: Remove the currently running container

docker rm -v redis

or using Docker Compose:

docker-compose rm -v redis

Step 4: Run the new image

Re-create your container from the new image, restoring your backup if necessary.

docker run --name redis bitnami/redis:latest

or using Docker Compose:

docker-compose start redis

Testing

This image is tested for expected runtime behavior, using the Bats testing framework. You can run the tests on your machine using the bats command.

bats test.sh

Contributing

We'd love for you to contribute to this container. You can request new features by creating an issue, or submit a pull request with your contribution.

Issues

If you encountered a problem running this container, you can file an issue. For us to provide better support, be sure to include the following information in your issue:

• Host OS and version
• Docker version (docker version)
• Output of docker info
• Version of this container (echo $BITNAMI_APP_VERSION inside the container)
• The command you used to run the container, and any relevant output you saw (masking any sensitive information)

License

Copyright 2015 Bitnami

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.