Beat Pulse

BeatPulse is a simple liveness, readiness library for .NET Core Applications.

What is the motivation behind it

The Microsoft HealthCheck library is not an active project right now and there is no plan to include this feature in ASP.NET Core 2.1.

Getting Started

1. Install the Nuget Package into your ASP.NET Core application.

Install-Package BeatPulse

2. Install the liveness libraries that you need on your project. At this moment BeatPulse contains libraries for Redis, SqlServer, MongoDb, Postgress Sql, Azure Storage (Blobs, Tables and Queues), DocumentDb, MySQL, SqLite and custom lambda liveness.

Install-Package BeatPulse.SqlServer
Install-Package BeatPulse.MongoDb
Install-Package BeatPulse.Npgsql
Install-Package BeatPulse.Redis
Install-Package BeatPulse.AzureStorage
Install-Package BeatPulse.MySql
Install-Package BeatPulse.DocumentDb
Install-Package BeatPulse.SqLite

3. Add BeatPulse into your ASP.NET Core project. UseBeatPulse is a new IWebHostBuilder extension method for register and configure BeatPulse.

 public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
               .UseBeatPulse(options=>
                {
                   options.SetAlternatePath("health") //default hc
                        .SetTimeout(milliseconds:1500) // default -1 infinitely
                        .EnableDetailedOutput(); //default false
                }).UseStartup<Startup>().Build();

4. Add BeatPulseService and set the liveness libraries to be used.

    services.AddBeatPulse(setup =>
    {
        //add custom liveness
        setup.Add(new ActionLiveness("cat", "catapi", async  httpContext =>
        {
            var httpClient = new HttpClient()
            {
                BaseAddress = new Uri("http://www.google.es")
            };

            var response = await httpClient.GetAsync(string.Empty);

            if (response.IsSuccessStatusCode)
            {
                return ("OK", true);
            }
            else
            {
                return ("the cat api is broken!", false);
            }
        }));

        //add sql server liveness
        setup.AddSqlServer("your-connection-string");
    });

5. Request BeatPulse to get liveness results.

By default, the global path get the information of all liveness checkers, including the out of box self check added. If DetailedOutput is true the information is a complete json result with liveness, time, and execution results.

curl curl http://your-domain/health
GET /health HTTP/1.1
Host: your-domain
User-Agent: curl/7.49.0
Accept: */*
HTTP/1.1 200 OK

{
    "Checks": [
    {
        "Name": "self",
        "Path":"_self",
        "Message": "OK",
        "MilliSeconds": 0,
        "Run": true,
        "IsHealthy": true
    },
    {
        "Name": "cat",
        "Path":"catapi",
        "Message": "OK",
        "MilliSeconds": 376,
        "Run": true,
        "IsHealthy": true
    },
    {
        "Name": "SqlServerHealthCheck",
        "Path":"sqlserver",
        "Message": "OK",
        "MilliSeconds": 309,
        "Run": true,
        "IsHealthy": true
    }
	],
	"StartedAtUtc": "2018-02-26T19:30:05.4058955Z",
	"EndAtUtc": "2018-02-26T19:30:06.0978236Z"
}

Optionally, you can get result for specific liveness adding the liveness segment path on the beat pulse base path.

http://your-domain/health/_self get the liveness status of the project without execute any configured liveness library. This is usual for the liveness path on k8s pods.

http://your-domain/health/[liveness-segment-path] get the liveness status of the specified liveness libraries. Each liveness library define a specified path. By default the Sql Server livenes library is sqlserver, for Redis is redis, for Postgress SQL is npgsql and for MongoDb is mongodb.

Cache responses

Beatpulse can cache its responses. There are two cache modes:

1. By using HTTP Headers. Using this model beatpulse adds a Cache-Control header with a value of public, max-age=xxx. It is up to user agents to honor this header.
2. In-memory. Using this model beatpulse stores the previous response and returns if the cache duration time has not elapsed.

To enable cache use the method EnableOutputCache:

    .UseBeatPulse(options=>
    {
        options.SetAlternatePath("health") //default hc
            .EnableOutputCache(10)      // Can use CacheMode as second parameter
            .SetTimeout(milliseconds:1500) // default -1 infinitely
            .EnableDetailedOutput(); //default false
    })

You can specify the cache method by using a second parameter with a CacheMode value (Header, ServerMemory or HeaderAndServerMemory) (default is Header).

If you perform two inmediate requests (because using a user-agent that do not follow the Cache-Control header) and in-memory cache is enabled you will receive the same response both times and all checks will be performed only once. If in-memory cache is not enabled all checks will be performed again.