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Serhat Teker
Serhat Teker

Posted on • Originally published at tech.serhatteker.com on

Connect Redis from Another Container

#docker #redis #network

1. Issue

I started a redis container in my local environment and now I want to connect and/or send data to it from another container.

1.1. Reproduce

1.1.1. docker cli

Let's assume that I started a redis container from cli:

$ docker run \ --name redislocal \ -p "6379:6379" \ redis:6.2.5
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Or in a more appropriate way:

$ docker run \ --name redislocal \ --hostname redislocal \ -p "127.0.0.1:6379:6379" \ -d \ redis:6.2.5 \ redis-server \ --appendonly yes \ --requirepass pa$$w0rD
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1.1.2. docker-compose

Maybe I started it via docker-compose:

$ docker-compose -f compose-redis-local.yml up -d --build
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And compose-redis-local.yml something like:

# compose-redis-local.yml version: "3.5" volumes: local_redis_data: {} services: redis: container_name: redislocal hostname: redislocal image: redis:6.2.5 command: redis-server --appendonly yes --requirepass pa$$w0rD ports: - "127.0.0.1:6379:6379" volumes: - local_redis_data:/data restart: unless-stopped
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2. Solution

Sorry: there is NO way you can connect to above redis containers from another container.

When you spawn containers from docker-compose —docker-compose example, docker will:

  1. Create a network mayapp_default with bridge driver (myapp is the directory you're in)
  2. Create redislocal container and add it to mayapp_default network under the name redis

Similar applies to docker cli.

2.1. Custom Network

What you need is a user defined custom shared network: You should create a custom network than respawn your containers in this network.

Create a network called local-dev:

$ docker network create local-dev
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Ensure it was created:

$ docker network ls NETWORK ID NAME DRIVER SCOPE 6d05d9ee7371 bridge bridge local ac5000845253 host host local d75701b57e1e kind bridge local 5bde7f533689 local-dev bridge local
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2.1.1. docker cli

Start within this network:

$ docker run \ --name redislocal \ --network local-dev -p "127.0.0.1:6379:6379" \ -d \ redis:6.2.5 \ redis-server \ --appendonly yes \ --requirepass pa$$w0rD
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2.1.2. docker-compose

Use this network as an external network in your compose file:

# compose-redis-local.yml version: "3.5" volumes: local_redis_data: {} services: redis: container_name: redislocal hostname: redislocal image: redis:6.2.5 command: redis-server --appendonly yes --requirepass 6te0valZ2L ports: - "127.0.0.1:6379:6379" volumes: - local_redis_data:/data networks: - local-dev networks: local-dev: external: true
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In addition to those, instead of User-defined bridge networks you can use host networks however I don't like this approach since it breaks the isolation nature of docker.

For more info you can look at this official docker docs:

3. Connect

Now you can connect in the same network:

$ docker run \ -it \ --rm \ --net local-dev \ redis:6.2.5 \ redis-cli -h redislocal -a pa$$w0rD ping PONG
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All done!

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