Redis Example

This project demonstrates how to set up and use Redis in both standalone and cluster configurations using Docker.

Prerequisites

Before you begin, ensure you have the following installed:

• Docker
• Yarn v1.22.17 or higher
• Node.js v14.17.0 or higher

Standalone Redis Instance

1. Start Redis Using Docker

To start a standalone Redis instance, run the following command:

yarn run start-redis

This will initiate the Redis container using the configuration in docker-compose.yml:

cache:
  image: redis:latest
  container_name: redis-cache
  restart: always
  ports:
    - "6379:6379"

This configuration sets up a Redis cache service listening on port 6379, which is typical for single-instance Redis deployments.

2. Start the Example Application

To start the example application using the standalone Redis instance, run:

yarn run start:single

3. Test the Application

You can test the APIs as follows:

• API without Redis caching: /getphoto
• API with Redis caching: /getphoto-redis

Redis Cluster

A Redis cluster is an advanced configuration that enhances performance, scalability, and fault tolerance by distributing data across multiple nodes.

1. Start Redis Cluster Using Docker

Run the following command to start the Redis cluster:

yarn run start-redis

In the docker-compose.yml file, the following environment variables are used:

• ALLOW_EMPTY_PASSWORD: Allows connections to the cluster without requiring credentials.
• REDIS_NODES: Specifies the hostnames of all nodes in the cluster, separated by spaces.
• REDIS_CLUSTER_REPLICAS: 1: Configures the cluster with three master nodes and three replica nodes across six nodes.

Execute the command to launch the Redis cluster:

docker-compose up

Logs:

redis-node-5  | >>> Performing Cluster Check (using node 172.18.0.2:6379)
redis-node-5  | M: 025420b382c7d631ebfe4959b346eaf255caeaba 172.18.0.2:6379
redis-node-5  |    slots:[0-5460] (5461 slots) master
redis-node-5  |    1 additional replica(s)
redis-node-5  | S: 1d693ab3d6b630768359615889bfcdc69642cea3 172.18.0.5:6379
redis-node-5  |    slots: (0 slots) slave
redis-node-5  |    replicates 025420b382c7d631ebfe4959b346eaf255caeaba
redis-node-5  | M: 9239ec8481a3ec411dd0f2f832d0f7a4b07472ef 172.18.0.6:6379
redis-node-5  |    slots:[10923-16383] (5461 slots) master
redis-node-5  |    1 additional replica(s)
redis-node-5  | S: 4d8b42ab42c2f589f31ea2310ccc630a899d71f1 172.18.0.7:6379
redis-node-5  |    slots: (0 slots) slave
redis-node-5  |    replicates 9c5e768c2aaae24e48bb62c0be8395d13592a940
redis-node-5  | S: 07fc9c307fc4fca6371e8832821638d412c8c350 172.18.0.4:6379
redis-node-5  |    slots: (0 slots) slave
redis-node-5  |    replicates 9239ec8481a3ec411dd0f2f832d0f7a4b07472ef
redis-node-5  | M: 9c5e768c2aaae24e48bb62c0be8395d13592a940 172.18.0.3:6379
redis-node-5  |    slots:[5461-10922] (5462 slots) master
redis-node-5  |    1 additional replica(s)
redis-node-5  | [OK] All nodes agree about slots configuration.
redis-node-5  | >>> Check for open slots...
redis-node-5  | >>> Check slots coverage...
redis-node-5  | [OK] All 16384 slots covered.
redis-node-5  | Cluster correctly created

You should see output indicating the successful creation of the cluster:

redis-node-5  | >>> Performing Cluster Check (using node 172.18.0.2:6379)
...
redis-node-5  | [OK] All 16384 slots covered.
redis-node-5  | Cluster correctly created

2. Connect to the Redis Cluster

To connect to a specific Redis container, list all running containers:

docker ps

Then, use the following command to access the container:

docker exec -it <container_id> sh

Once inside the container, you can start the Redis CLI:

redis-cli -c

To view all nodes in the cluster, run:

CLUSTER NODES

Logs:

127.0.0.1:6379> CLUSTER NODES
82d2bee961c7a4b73f099550d72a232e55d12d60 172.18.0.2:6379@16379 master - 0 1683707451345 2 connected 5461-10922
e09bd0f03f71d5ca9e1db6804ac28f2470eb70db 172.18.0.7:6379@16379 myself,slave 82d2bee961c7a4b73f099550d72a232e55d12d60 0 1683707449000 2 connected
8cb609962e074807b56f1a01bbbde3e6a436e7ca 172.18.0.3:6379@16379 master - 0 1683707450331 1 connected 0-5460
7dd24d5ffc732189f7b32a5468d9b20ebc1f60d7 172.18.0.5:6379@16379 master - 0 1683707450000 3 connected 10923-16383
c02f2c7285074d9d5b23b8faf07ec287c6e94636 172.18.0.4:6379@16379 slave 8cb609962e074807b56f1a01bbbde3e6a436e7ca 0 1683707449316 1 connected
5105b2780cabbff516e0f834a694bcdca310e8b7 172.18.0.6:6379@16379 slave 7dd24d5ffc732189f7b32a5468d9b20ebc1f60d7 0 1683707448291 3 connected

You can now set a value in the cluster:

SET key "value"

127.0.0.1:6379> SET key "value"
-> Redirected to slot [12539] located at 172.18.0.5:6379
OK

3. Running the Example Application

Start the application configured for the Redis cluster:

yarn run start:multiple

4. Test the Application

Test the APIs as follows:

• API without Redis caching: /getphoto
• API with Redis caching: /getphoto-redis

Outside Docker Network (MacOS)

For MacOS, to connect to the Redis cluster from outside the Docker network, first retrieve your external host IP:

echo "$(route get uninterrupted.tech | grep interface | sed -e 's/.*: //' | xargs ipconfig getifaddr)"

Update the REDIS_NODES environment variable in the docker-compose.yml file with the retrieved IP:

REDIS_NODES: <external_ip>:6370 <external_ip>:6371 <external_ip>:6372 <external_ip>:6373 <external_ip>:6374 <external_ip>:6375

You can then connect to the Redis cluster and run the CLUSTER NODES command as described earlier.

❯ redis-cli -c -h 192.168.1.13 -p 6375
127.0.0.1:6375> CLUSTER NODES
275c337ffe6073071088bb0706a2536608c03fe9 192.168.1.184:6372@16372 master - 0 1683717016000 3 connected 10923-16383
0e779e30ce3879ee37b470b299a97d41c0e16779 192.168.1.184:6370@16370 master - 0 1683717018000 1 connected 0-5460
3e7dc06681938425f71a39a2a7d189b336132e4a 192.168.1.184:6374@16374 slave 0e779e30ce3879ee37b470b299a97d41c0e16779 0 1683717020706 1 connected
841b05c2890454b345da8380ee63fa41c03fae6b 192.168.1.184:6371@16371 master - 0 1683717020000 2 connected 5461-10922
44444520eb2bbc346ab4dba9b1c495973399a227 192.168.1.184:6375@16375 myself,slave 841b05c2890454b345da8380ee63fa41c03fae6b 0 1683717017000 2 connected
8f14d7d1faac0e131d315ee34c0c7fc3836716c9 192.168.1.184:6373@16373 slave 275c337ffe6073071088bb0706a2536608c03fe9 0 1683717019000 3 connected