krun

krun

A command-line tool for building, deploying, and debugging microservices in Kubernetes environments.

Features

• Build Docker images for services
• Deploy services to Kubernetes
• Enable/disable debug mode for services using Telepresence

Installation

1. Ensure you have the following dependencies installed:

   • kubectl
   • telepresence

2. Get the latest version of krun from the releases page.

3. Unzip the downloaded file to a directory in your PATH, or add the directory to your PATH.

4. Place a krun.json file in the root of your project repository to define your services. See the krun.json section for details.

5. Follow the debugging instructions to set up your project for debugging with Telepresence.

Usage

krun [global options] <command> [command options] <service>

Global Options

• --kubeconfig <path>: Path to kubeconfig file (default: ~/.kube/config)

Commands

• help
  Show help message.

• version
  Show version information.

• build [--skip-web, --force, --flush] <project|service>
  Build a project or specific service.
  Use --skip-web to skip building the web service, --force to force a rebuild even if the source has not changed, and --flush to delete the existing build pod before building (clearing any cached layers or copied workspace files).

  krun build awesome-app
  krun build --skip-web awesome-app
  krun build --skip-web --force awesome-app
  krun build --flush awesome-app
  

• deploy [--use-remote-registry] <project>
  Deploy a project.
  Use --use-remote-registry to deploy using the remote Docker registry defined in krun-config.json. If not specified, it will use the local Docker registry.

  krun deploy awesome-app
  krun deploy --use-remote-registry awesome-app
  

• debug list
  List all services with their debug status.

  krun debug list
  

• debug enable <service> [--intercept, --container <container>]
  Enable debug mode for a service using Telepresence.
  Use --intercept to intercept the service in the Kubernetes cluster, allowing you to run it both locally and in the cluster.
  If --intercept is not specified, it will replace the service in the cluster and redirect traffic to your local debug session.

  krun debug enable awesome-app-api
  krun debug enable awesome-app-api --intercept
  

  Both replace and intercept mode need a port configured that matches the port your application is listening on. For example, a C# web api application usually listens on port 5000 which is defined in the launchSettings.json file. To make this available for krun, you need to add the intercept_port property in your krun.json file for the service you want to debug.

Use the --container option to specify which container to debug if your pod has multiple containers.

krun debug enable awesome-app-api --container awesome-app-api

• debug disable <service>
  Disable debug mode for a service.

  krun debug disable awesome-app-api
  

Examples

1. Build the entire project:

   krun build awesome-app
   

2. Build the project without the web service:

   krun build --skip-web awesome-app
   

3. Build a specific service:

   krun build awesome-app-api
   

4. Deploy a service:

   krun deploy awesome-app-api
   

5. Enable debug mode:

   krun debug enable awesome-app-api
   

6. Enable debug mode for specific conttainer:

   krun debug enable awesome-app-api --container mysidecar
   

7. Disable debug mode:

   krun debug disable awesome-app-api
   

krun-config.json

The krun-config.json file configures how krun interacts with your Kubernetes environment, Docker registries, and source code. Below is a description of each field:

Example

{
  "source": {
    "path": "c:/git/",
    "search_depth": 1
  },
  "hostname": "kube.local",
  "local_registry": "registry:5000",
  "remote_registry": "docker.io/ftechmax"
}

Field Reference

• source

  • path: Root directory where your project source code is located.
  • search_depth: How many directory levels to search for services in path.

• hostname: The hostname of the Kubernetes server.

• local_registry: Address of your local Docker registry (used for local builds).

• remote_registry: Address of the remote Docker registry (used for deploying non-local builds).

Notes
Ensure all paths use forward slashes or are properly escaped for your operating system.
Make sure your kubeconfig is correctly configured.

krun.json

The krun.json file is used by krun to detect available services in your project. It should be placed in the root of your project repository and contains an array of service definitions.

Example

[
  {
    "name": "awesome-app-worker",
    "path": "src/worker",
    "dockerfile": "AwesomeApp.Worker",
    "context": "src/",
    "container_port": 8080
  },
  {
    "name": "awesome-app-api",
    "path": "src/api",
    "dockerfile": "AwesomeApp.Api",
    "context": "src/"
  },
  {
    "name": "awesome-app-web",
    "path": "src/web",
    "dockerfile": ".",
    "context": "src/web"
  }
]

Field Reference

• name: The name of the service as it will be referenced in commands. Make sure this matches the name in your deployment.yaml files.

• path: The relative path to the service directory from the root of your project. This is where the Dockerfile and source code for the service are located.

• dockerfile: The path where the Dockerfile is located relative to the path directory. If the Dockerfile is in the service directory, you can use ".".

• context: The build context for the Docker image. This is the directory that will be sent to the Docker daemon during the build process. If you have a shared project between multiple services, you can set this to the parent directory of the service directories as shown in the example.

• container_port (optional): The port of the container running inside the service pod. This is used for debugging and should match the port exposed by your service container.

  NOTE: The default is 8080 if not specified.

Debugging with Telepresence

To debug a service using Telepresence, you can enable debug mode for that service. This will allow you to run your project locally while still connected to the Kubernetes cluster.

Prerequisites

Ensure your project launches as a console application (which is the default profile).

Enabling Debug Mode

To enable debug mode for a service, use the following command:

krun debug enable <service>

Disabling Debug Mode

To disable debug mode for a service, use the following command:

krun debug disable <service>

Inject Kubernetes Environment Variables

To inject Kubernetes environment variables into your project when in debug mode, you have to consume the appsettings-debug.env file that the debug mode creates in your solution directory.

Add the following in your program.cs file.

For WebApplication builder

var builder = WebApplication.CreateBuilder(args);

ConfigureConfiguration(builder);

private static void ConfigureConfiguration(WebApplicationBuilder builder)
{
    if (!builder.Environment.IsDevelopment())
    {
        return;
    }

    // Read appsettings-debug.env and inject each line as environment variable
    var envFile = Path.Combine("../appsettings-debug.env");
    if (File.Exists(envFile))
    {
        foreach (var line in File.ReadAllLines(envFile))
        {
            var trimmed = line.Trim();
            if (string.IsNullOrWhiteSpace(trimmed) || trimmed.StartsWith("#")) continue;
            var separatorIndex = trimmed.IndexOf('=');
            if (separatorIndex > 0)
            {
                var key = trimmed.Substring(0, separatorIndex).Trim();
                var value = trimmed.Substring(separatorIndex + 1).Trim();
                if (!string.IsNullOrEmpty(key))
                {
                    Environment.SetEnvironmentVariable(key, value);
                }
            }
        }
    }

    // Read environment variables into the configuration
    builder.Configuration.AddEnvironmentVariables();
}

For Default Host builder

var builder = Host.CreateDefaultBuilder(args);

builder.ConfigureAppConfiguration(ConFigureConfiguration);

private static void ConFigureConfiguration(HostBuilderContext context, IConfigurationBuilder config)
{
    if (!context.HostingEnvironment.IsDevelopment())
    {
        return;
    }

    // Read appsettings-debug.env and inject each line as environment variable
    var envFile = Path.Combine("../appsettings-debug.env");
    if (File.Exists(envFile))
    {
        foreach (var line in File.ReadAllLines(envFile))
        {
            var trimmed = line.Trim();
            if (string.IsNullOrWhiteSpace(trimmed) || trimmed.StartsWith("#")) continue;
            var separatorIndex = trimmed.IndexOf('=');
            if (separatorIndex > 0)
            {
                var key = trimmed.Substring(0, separatorIndex).Trim();
                var value = trimmed.Substring(separatorIndex + 1).Trim();
                if (!string.IsNullOrEmpty(key))
                {
                    Environment.SetEnvironmentVariable(key, value);
                }
            }
        }
    }

    // Read environment variables into the configuration
    config.AddEnvironmentVariables();
}