µ-Gouldian

Go combinator library for building containerized and serverless HTTP services.

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The library is a thin layer of purely functional abstractions to build HTTP services. In the contrast with other HTTP routers, the library resolves a challenge of building simple and declarative api implementations in the absence of pattern matching at Golang. The library also support opaque migration of HTTP service between traditional, containers and serverless environments.

User Guide | Hello World | Other Examples | Benchmark

Inspiration

Microservices have become a design style to evolve system architecture in parallel, implement stable and consistent interfaces within distributed system. An expressive language is required to design the manifold of network interfaces. A pure functional languages fits very well to express communication behavior due they rich techniques to hide the networking complexity. Finch is the best library in Scala for microservice development. Gouldian is heavily inspired by Finch.

The library solves few practical problems of HTTP service development in Golang:

• The library support opaque migration of HTTP service between traditional, containers and serverless environments. The api implementation remains source compatible regardless the execution environment; The library supports integration with
  • Golang standard HTTP server: http.Request
  • AWS API Gateway: APIGatewayProxyRequest.
• The library enforces a type safe, pattern-based approach for api definition.
• Fast, zero allocation routing

Installing

The library requires Go 1.18 or later.

The latest version of the library is available at main branch. All development, including new features and bug fixes, take place on the main branch using forking and pull requests as described in contribution guidelines. The stable version is available via Golang modules.

1. Use go get to retrieve the library and add it as dependency to your application.

go get -u github.com/fogfish/gouldian

2. Import it in your code

import (
  µ "github.com/fogfish/gouldian"
)

Quick Example

Here is minimal "Hello World!" example that matches any HTTP requests to /hello endpoint. You can run this example locally see the instructions.

package main

import (
  µ "github.com/fogfish/gouldian"
  "github.com/fogfish/gouldian/server/httpd"
  "net/http"
)

func main() {
  http.ListenAndServe(":8080",
    httpd.Serve(hello()),
  )
}

func hello() µ.Routable {
  return µ.GET(
    µ.URI(µ.Path("hello")),
    func(ctx µ.Context) error {
      return µ.Status.OK(µ.WithText("Hello World!"))
    },
  )
}

Benchmark

The library uses go-http-routing-benchmark methodology for benchmarking, using structure of GitHub API as primary benchmark. The results are obtained on the reference hardware such as AWS m6i.large and a1.large instances.

m6i.large 3.5 GHz 3rd generation Intel Xeon Scalable processors:

• It takes 10.9M routing decisions per second, taking about 110 ns/op and consuming about 0 allocs/ops.
• It performs 7.4M requests/responses for the single endpoint with one parameter, taking about 162 ns/op and consuming 24 B/op with 2 allocs/op.

a1.large AWS Graviton Processor with 64-bit Arm Neoverse cores:

• It takes 2M routing decisions per second, taking about 520 ns/op and consuming about 0 allocs/ops.
• It performs 1.5M requests/responses for the single endpoint with one parameter, taking about 763 ns/op and consuming 24 B/op with 2 allocs/op.

Next steps

• Study User Guide.

• Check build-in collection of endpoints to deal with HTTP request: path, query param, http header, body and other

• Endpoint always returns some Output that defines HTTP response. There are three cases of output: HTTP Success, HTTP Failure and general error. See Output type.

• See example folder for other advanced use-case.

• Learn about microservice deployment with AWS CDK, in case of serverless development

How To Contribute

The library is Apache 2.0 licensed and accepts contributions via GitHub pull requests:

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

The build and testing process requires Go version 1.13 or later.

Build and run in your development console.

git clone https://github.com/fogfish/gouldian
cd gouldian
go test
go test -run=^$ -bench=. -cpu 1

commit message

The commit message helps us to write a good release note, speed-up review process. The message should address two question what changed and why. The project follows the template defined by chapter Contributing to a Project of Git book.

bugs

If you experience any issues with the library, please let us know via GitHub issues. We appreciate detailed and accurate reports that help us to identity and replicate the issue.

License