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Version: 3.22.0

Distributed Cache

Redis Cache is used for caching as distributed. Besides, .Net Core's In-Memory Cache can be used interchangeably with a slight effort.

Redis is an open source, in-memory data structure store, used as a database, cache and message broker. It supports data structures such as strings, hashes, lists, sets and so on. For more visit https://redis.io/

Redis server's url can be changed from coresettings.json file or can be overridden in any other appsettings files for different environments.

...
"Redis":  {  
    "Url":  "127.0.0.1:6379,password={PASSWORD}",  
    "DatabaseIndex": 0
}
...

Url : Connection configuration of redis. Check out this link for more information.

DatabaseIndex : (0-15) Redis instance supports 16 databases. Each database provides a distinct keyspace, independent from the others. You can specify which database to be used by index.

How Redis is benefited in the solution?​

Currently, Session, Permissions, Parameters, Service Definitions and some EF Core queries are stored in Redis. They can therefore support an order of magnitude more operations and faster response times.

EF Core Query Caching​

The results of EF commands will be stored in the cache, so that the same EF commands will retrieve their data from the cache rather than executing them against the database again.

You can simply use Cacheable method and configure expiration for any IQueryable queries.

Configuration​

CoreSvc/Startup.cs
// Redis
services.AddEasyCaching(option =>
   option.UseRedis(config => config.DBConfig.Configuration = ConfigurationManager.RedisSettings.Url, "EasyCacheRedisProvider")
);

// EF Core Query Caching
services.AddEFSecondLevelCache(options => options.UseEasyCachingCoreProvider("EasyCacheRedisProvider"));

Usages​

context.Posts
   .Where(x => x.Id > 0)
   .OrderBy(x => x.Id)
   .Cacheable(CacheExpirationMode.Sliding, TimeSpan.FromMinutes(5))
   .ToList();
await GetAsQueryable(entity)
   .Cacheable(CacheExpirationMode.Absolute, TimeSpan.FromMinutes(1)) // Stores query result in the cache for a minute.
   .FirstOrDefaultAsync();

Check out this link for more information.

Secure Redis Server​

Authentication​

Require clients to issue AUTH }<PASSWORD>{ before processing any other commands. This might be useful in environments in which you do not trust others with access to the host running redis-server.

1) Open redis.conf file and change password to a very long & strong password. Docker will mount this file on next run. You can restart existing containers to affect changes.

requirepass <YOUR_PASSWORD>

2) Open coresettings.json and any other appsettings file that overrides those properties to replace old password with the new one.

...
"Redis": {
  "Url": "...,password=<YOUR_PASSWORD>",
  ...
}
...

Network Security​

Access to the Redis port (default 6379) should be denied to everybody but trusted clients in the network, so the servers running Redis should be directly accessible only by the computers implementing the application using Redis.

For comprehensive security instructions, visit https://redis.io/topics/security

Separating Databases for each multiple unrelated application​

Out of the box, every Redis instance supports 16 databases. The database index is the number you see at the end of a Redis URL: redis://localhost:6379/0. The default database is 0 but you can change that to any number from 0-15 (and you can configure Redis to support more databases, look in redis.conf).

Each database provides a distinct keyspace, independent from the others. Use SELECT n to change databases. Use FLUSHDB to flush the current database. You can MOVE a key from the current database to another database.

In practical terms, Redis databases should be used to separate different keys belonging to the same application (if needed), and not to use a single Redis instance for multiple unrelated applications.

So, for unrelated applications those use same Redis server, you can override DatabaseIndex by any appsettings files.

"Redis": {
    // "Url": "This value will be inherited from 'coresettings' file."
    "DatabaseIndex": <INDEX> // You can use any number between 0-15
}

Using separate databases is an easy way to put a “firewall” between datasets without any additional administrative overhead. Now you can FLUSHDB one dataset without affecting another dataset.

Protip: configure your test suites to use a different database than your development environment so the test suite can FLUSHDB without destroying development data.

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