Redis Notes

11 May, 2023

Described as an 'in-memory data store' that can be used as a database, cache or message broker. It supports various types of persistent storage also - dumping data to a disk or writing transaction logs. On a Linux system, the data is written to /var/redis by default. The configuration files can be created in /etc/redis. An instance of Redis might also require an file in /etc/init.d.

Related components:

• Redis Sentinel
• Redis Cluster

Redis CLI

Check if the Redis server is running:

redis-cli ping

Start the Redis command line interface:

redis-cli

Set a row, or key-value:

set mykey somevalue

Read a value for a key:

get mykey

Write dataset and changes to persistent storage:

redis-cli save
redis-cli shutdown

Security

Redis has no authentication or access control by default.

• If deploying to an internal network, configure the firewall to block ports 6379 and 16379 for external IP addresses.
• Use bind to ensure Redis only listens on the specific port for that service.
• Use requirepass to apply authentication, so only authorised applications are able to query or write to the data. They will need to use the AUTH command for this.
• Use spiped to create an encrypted tunnel for Redis traffic.

Core Data Types

• Strings: The basic data type.
• Lists: A list is a list of strings, sorted in the order they were inserted into the data set.
• Sets: A set is an unordered collection of strings. This could be useful for applications that need to perform a lookup to determine whether a given value exists in a dataset.
• Sorted Sets: A Sorted Set is an ordered collection of strings.
• Hashes: A hash is stored as a key-value pair.
• Streams: This is an append-only data structure, used ideally for recording events in the order they were appended.
• Geospatial Index: For applications that require geospatial data.
• Bitmaps: Not sure why this is included, but it facilitates bitwise operations on strings, which are stored as byte sequences.
• Bitfields: These can be strings that are used as bit counters. Supported operations are get, set and increment.

Using Redis with .NET

Import assembly references:

using NRedisStack;
using NRedisStack.RedisStackCommands;
using StackExchange.Redis;

Instantiate Redis client:

ConnectionMultiplexer redis = ConnectionMultiplexer.Connect("[server address]");
IDatabase db = redis.GetDatabase();

To instantiate a Redis client that requires authentication:

ConfigurationOptions options = new ConfigurationOptions
{
    EndPoints = { { "[redis server address]", 6379 } },
    User = "[user]",
    Password = "[password]",
    Ssl = true,
    SslProtocols = System.Security.Authentication.SslProtocols.Tls12                
};

options.CertificateSelection += delegate
{
    return new X509Certificate2("[PFX file location]", "[password]");
};

ConnectionMultiplexer muxer = ConnectionMultiplexer.Connect(options);   

IDatabase conn = muxer.GetDatabase();

The User and Password values should be read from appsettings/configuration file, rather than hard-coded.

Resources

Redis Site Redis @ GitHub Redis: Getting Started# Redis and .NET

#development