tye/docs/redis.md

Adding redis to an application

This tutorial assumes that you have completed the Frontend Backend Run Sample and Frontend Backend Deploy Sample.

We just showed how tye makes it easier to communicate between 2 applications running locally but what happens if we want to use redis to store weather information?

Tye can use docker to run images that run as part of your application. If you haven't already, make sure docker is installed on your operating system (install docker) .

1. To create a tye manifest from the solution file.

   tye init microservice.sln
   

   This will create a manifest called tye.yaml with the following contents:

    name: microservice
    services:
    - name: frontend
        project: frontend\frontend.csproj
    - name: backend
        project: backend\backend.csproj
   

   This will be the source of truth for tye execution from now on. To see a full schema of file, see the reference in the schema reference.

2. Change the WeatherForecastController.Get method in the backend project to cache the weather information in redis using an IDistributedCache.

   [HttpGet]
   public async Task<string> Get([FromServices]IDistributedCache cache)
   {
       var weather = await cache.GetStringAsync("weather");
   
       if (weather == null)
       {
           var rng = new Random();
           var forecasts = Enumerable.Range(1, 5).Select(index => new WeatherForecast
           {
               Date = DateTime.Now.AddDays(index),
               TemperatureC = rng.Next(-20, 55),
               Summary = Summaries[rng.Next(Summaries.Length)]
           })
           .ToArray();
   
           weather = JsonSerializer.Serialize(forecasts);
   
           await cache.SetStringAsync("weather", weather, new DistributedCacheEntryOptions
           {
               AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(15)
           });
       }
       return weather;
   }
   

   This will store the weather data in Redis with an expiration time of 15 seconds.

3. Add a package reference to Microsoft.Extensions.Caching.StackExchangeRedis in the backend project:

   cd backend/
   dotnet add package Microsoft.Extensions.Caching.StackExchangeRedis
   

4. Modify Startup.ConfigureServices in the backend project to add the redis IDistributedCache implementation.

   public void ConfigureServices(IServiceCollection services)
   {
       services.AddControllers();
   
       services.AddStackExchangeRedisCache(o =>
       {
            var connectionString = Configuration["connectionstring:redis"];
            if (connectionString != null)
            {
                o.Configuration = connectionString;
            }
            else
            {
                o.Configuration = $"{Configuration["service:redis:host"]}:{Configuration["service:redis:port"]}";
            }
        });
   }
   

   The above configures redis to use the host and port for the redis service injected by the tye host.

5. Modify tye.yaml to include redis as a dependency.

    name: microservice
    services:
    - name: backend
        project: backend\backend.csproj
    - name: frontend
        project: frontend\frontend.csproj
    - name: redis
        dockerImage: redis
        bindings:
        - port: 6379
    - name: redis-cli
        dockerImage: redis
        args: "redis-cli -h host.docker.internal MONITOR"
   

   We've added 2 services to the tye.yaml file. The redis service itself and a redis-cli service that we will use to watch the data being sent to and retrieved from redis.

6. Run the tye command line in the solution root

   tye run
   

   Navigate to http://localhost:8000 to see the dashboard running. Now you will see both redis and the redis-cli running. Navigate to the frontend application and verify that the data returned is the same after refreshing the page multiple times. New content will be loaded every 15 seconds, so if you wait that long and refresh again, you should see new data. You can also look at the redis-cli logs and see what data is being cached in redis.

Deploying redis

1. Deploy redis to Kubernetes

   tye deploy will not deploy the redis configuration, so you need to deploy it first. Run:

   kubectl apply -f https://raw.githubusercontent.com/dotnet/tye/d79f790ba13791c1964ed03c31da0cd12b101f39/docs/yaml/redis.yaml?token=AB7K4FLEULBCQQU6NLXZEDC6OPIU4
   

   This will create a deployment and service for redis. You can see that by running:

   kubectl get deployments
   

   You will see redis deployed and running.

2. Deploy to Kubernetes

   Next, deploy the rest of the application by running.

   tye deploy
   

3. Test it out!

   You should now see three pods running after deploying.

   kubectl get pods
   

   NAME                                             READY   STATUS    RESTARTS   AGE
   backend-ccfcd756f-xk2q9                          1/1     Running   0          85m
   frontend-84bbdf4f7d-6r5zp                        1/1     Running   0          85m
   redis-5f554bd8bd-rv26p                           1/1     Running   0          98m