developers-guide.md

Developer's Guide

This document explains how to setup the development enviornment for this project.

Durable Scale Server Development

Server code is written by gRPC service with ASP.NET Core.

Configration

If you are using Visual Studio 2019, you can configure the visual studio for enabling local debugging.

launchSettings.json

You can add Properties/launchSettings.json under Keda.Durable.Scaler.Server. It configures deubgging time enviornment variables and providing configuration for gRPC service. For the detail configration of the environment variables, please refer the KEDA Durable Scaler Configration. applicationUrl is the URL for the Server endpoint. If you want to test HTTPS protocol, you can make it as https://localhost:5001.

{
  "profiles": {
    "Keda.Durable.Scaler.Server": {
      "commandName": "Project",
      "environmentVariables": {
        "CONNECTION_STRING": "<YOUR_STORAGE_ACCOUNT_CONNECTION_STRING_HERE>",
        "TASK_HUB": "DurableFunctionsHub",
        "MAX_POLLING_INTERVAL": "5000",
        "ASPNETCORE_ENVIRONMENT": "Development",
        "CERT_PATH": "C:\\Users\\tsushi\\grpcsv.pfx",
        "CERT_PASS": "keda"
      },
      "applicationUrl": "http://localhost:5000"
    },
    "Docker": {
      "commandName": "Docker",
      "launchUrl": "{Scheme}://{ServiceHost}:{ServicePort}",
      "environmentVariables": {
        "CONNECTION_STRING": "<YOUR_STORAGE_ACCOUNT_CONNECTION_STRING_HERE>",
        "TASK_HUB": "DurableFunctionsHub",
        "MAX_POLLING_INTERVAL": "5000",
        "ASPNETCORE_ENVIRONMENT": "Development"
      },
      "httpPort": 5000
    },
   }
}   

kubeconfig

You can place kubeconfig file for your local debugging. Get the kubeconfig file and put it under Keda.Durable.Scaler.Server. It is under the .gitignore file. Don't forget make kubeconifg as Copy always.

For getting the kubeconfig of your kubernes cluster, if you are using Azure, you can do like this.

$ az aks get-credentials --name MyManagedCluster --resource-group MyResourceGroup

Then you can find the kubeconfig file under ~/.kube/config copy it as kubeconfig and put it under the Keda.Durable.Scaler.Server.

Secret and Crtificate

You can refer Getting Started to create and configure certificate for https.

Important Classes

For reading this code, there is several important files are there.

ExternalScalerService

Core logic of the scaling. This class implement scaler logic of this server. It uses, DurableTask.DisconnectPerformanceMonitor for getting analytics data nad telemetry.

externalscaler.proto

Protocol buffer of the External Scaler Support for KEDA. Usually, you might need to generate code from this buffer. It is automatically done by gRPC services with ASP.NET Core. You can see the generated file under the obj directory, however, you don't need commit these files to the repo.

Startup.cs

It contains DI configration for the server, it also include Enviornment Variables configration for the Server.

Update images

If you want to test the image of this server, you can copy and modify the ../deploy/build_push_image.sh. The script help to build/deploy docker images and push to the DockerHub. Don't forget to change the image name for your own. You also need to modify [../deploy/deployment.yml] for deploying it.

Run Server locally

If you want to run the server locally, after executing the docker build, you can try this command.

$ docker build . -t durable-server
$ docker run -d -e "AzureWebJobsStorage=<YOUR_STORAGE_ACCOUNT_CONNECTION_STRING_HERE>" -e "FUNCTIONS_WORKER_RUNTIME=dotnet" -e "WEBSITE_HOSTNAME=localhost:80" -p 8802:80 durable-sever

Durable Functions Development

You can develop the Durable Functions for deploying to kubernetes. However, there is some consideration required to make it work. I explain some tips on Getting Started. Please refer it first.

I also add how to configure development enviornment. If you want to debug locally, you need to use Azure Functions Core Tools

local.settings.json

You can copy and modify local.settings.json.example.

$ cp local.settings.json.example local.setting.json

Modify <YOUR_STORAGE_CONNECTION_STRING_HERE> to your Storage Account Connection String that is used by Durable FUnctions.

local.settings.json

{
    "IsEncrypted": false,
    "Values": {
        "AzureWebJobsStorage": "<YOUR_STORAGE_CONNECTION_STRING_HERE>",
        "FUNCTIONS_WORKER_RUNTIME": "dotnet"
    }
}