How to access Redis from inside Docker and run queries

Concept

Redis is an open-source, in-memory key-value data store. It offers a versatile set of in-memory data structures that make it easy to build a wide range of custom applications. The most common Redis use cases include caching, session management, PUB/SUB, and leaderboards. It's the best-known key-value store today. It's BSD-licensed, written in optimized C, and supported by many programming languages. Redis stands for REmote DIctionary Server. (Source).

It stores lists, sets, strings, and hashes. It's highly performant, great for query caching and managing job scheduling queues.

Using it

There are plenty of articles online about installing Redis with Docker. After installing it, I wanted to inspect what was being persisted in memory — i.e., inside the Redis key/value store.

Accessing Redis from inside the Docker container:

docker exec -it redisbarber sh

Now I just need to enter the Redis CLI by typing redis-cli:

/data # redis-cli

If everything works, you'll see the IP and port, and a prompt waiting for commands:

127.0.0.1:6379>

The two most useful commands for me so far have been:

List all keys (they're strings):

127.0.0.1:6379> keys *

Output:

1. "bq:CancellationMail:id"
2. "cache:providers"
3. ... Note: there were many others that I'm omitting here.

To fetch a specific key, just type KEYS "key name":

127.0.0.1:6379> KEYS "cache:providers"

And to get the value of a key:

127.0.0.1:6379> MGET key "cache:providers"

1. (nil)
2. "JSON array with provider objects (values omitted for brevity)" 127.0.0.1:6379>

It returned an array with several objects. For context, this is the cache of a database query that returns my providers. If you'd like a post on how to handle caching in Node using Redis, drop a comment: Post about caching with Node + Redis.

So, to recap, the commands are:

docker exec -it redisbarber sh

/data # redis-cli

keys *

KEYS "cache:providers"

MGET key "cache:providers"

Cheers =)