Why do we need to install Redis? When is it used? Why Redis is needed? #6344

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  alper created 4 months ago

  Support Team Director

  As a summary

  • If you deploy your application as multiple instances, you need a distributed cache, like Redis.
  • If you have multiple applications (like a microservice or distributed solution) that need to share the same cache objects, you need to have a distributed cache, like Redis.
  • ABP's default cache is In-Memory Cache. It is usable only if you have a single application with a single instance running on a single server. Even in that scenario, it's good to use Redis because your cached objects are not erased when the application restarts.

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  What's Redis?

  • Redis (REmote DIctionary Server). This open-source application provides in-memory caching. It is known for its high-performance capabilities.

  • It’s very fast for reading/writing data. That’s why we use Redis for distributed cache in the following projects

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  Where is Redis being used in ABP projects?

  • AuthServer https://github.com/abpframework/abp/blob/dev/templates/app/aspnet-core/src/MyCompanyName.MyProjectName.AuthServer/appsettings.json
  • DbMigrator https://github.com/abpframework/abp/blob/dev/templates/app/aspnet-core/src/MyCompanyName.MyProjectName.DbMigrator/appsettings.json
  • Web.Host https://github.com/abpframework/abp/blob/dev/templates/app/aspnet-core/src/MyCompanyName.MyProjectName.Web.Host/appsettings.json
  • HttpApi.Host https://github.com/abpframework/abp/blob/dev/templates/app/aspnet-core/src/MyCompanyName.MyProjectName.HttpApi.Host/appsettings.json
  • Blazor.Server.Tiered https://github.com/abpframework/abp/blob/dev/templates/app/aspnet-core/src/MyCompanyName.MyProjectName.Blazor.Server.Tiered/appsettings.json

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  Why must we use Redis in ABP projects?

  You only need to install Redis for the n-tier architecture where Web and HTTP API layers are physically separated. If you work on an n-layered solution with no HTTP API project, then you don't need Redis.

  You can see in which cases Redis is pre-required from the documentation page: docs.abp.io/en/abp/latest/Getting-Started-Setup-Environment?UI=MVC&DB=EF&Tiered=Yes

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  What exactly is being cached in Redis?

  • When you see the IDistributedCache interface, it means Redis is required by default. The following modules are already using Redis (some modules are commercial modules):

    • setting-management:SettingManagementStore for setting values.
    • permission-management: PermissionStore for granted permissions.
    • saas:TenantDeletedHandler and TenantStore class
    • cms-kit: UrlShortingPublicAppService class for Shortened URL Caches
    • language-management: DynamicResourceLocalizer class for the Language Text caches
    • file-management: FileDescriptorAppService class for the Download Token Cache.
    • text-template-management: DynamicTemplateDefinitionStore class
    • gdpr: GdprRequestAppService class for Download Token Cache.

  Finally, I want you to know that you can replace Redis with any other caching provider like Memcached.

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  Resources:

  • docs.abp.io/en/abp/latest/caching
  • docs.abp.io/en/abp/latest/Deployment/Clustered-Environment#switching-to-a-distributed-cache

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