Cover Whale Go

This is somewhat of an opinionated set of packages for Go development. By no means is this going to be forced as the only way to write Go, but it's a good starting point for most things.

Code Generation

The cwgoctl code generator will create an opinionated Go application for you. It will create a Makefile, Dockerfile, started cmd package, starter server package, goreleaser config, and github actions.

Pre-Reqs

To use the targets in the Makefile you will need:

1. Go
2. k3d
3. kubectl
4. Docker Desktop (or regular Docker if on Linux)

Usage

To use the utility simply follow these steps:

1. go mod init github.com/CoverWhale/myapp

2. Run cwgoctl with your options. For example: cwgoctl new server --name myapp

   Cli documentation is here

3. Run make tidy

   Pulls in all dependencies and vendors them

4. Run make deploy-local

   Builds a local 3 node kubernetes cluster with registry using k3d and deploys your app to the cluster.

5. You can hit your running example app at myapp.127.0.0.1.nip.io:8080/api/v1/testing -H "Authorization: test"

   A default edgedb instance is also stood up for you. The URL for the edgedb ui can be found in the output of make deploy-local that was ran in step 4.

6. Now you can modify the code. For example adding handlers or creating another subrouter in the server package.

Extra flags

The utility has various flags to enable features that may be useful for the new app. For example: cwgoctl new server --name myapp --enable-nats --enable-graphql

1. --enable-nats

   Sets up a NATS integration.

2. --enable-graphql

   Sets up a GraphQL integration. A playground can be reached at myapp.127.0.0.1.nip.io:8080/playground

EdgeDB instructions

By default, your new CoverWhale app comes with edgedb enabled. Files related to edgedb can be found under the dbschema folder of your new app. To access your edgedb instance, follow these steps:

1. If you haven't already, run make tidy and make deploy-local to spin up a local kubernetes deployment

   Steps 3 & 4 from above. You will need to have docker running in order for the deploy to work

2. Port forward the edgedb service to your local machine kubectl port-forward svc/edgedb 5656:5656

3. Create a migration edgedb --dsn=edgedb://localhost:5656/edgedb --tls-security=insecure migration create

4. Run the migration edgedb --dsn=edgedb://localhost:5656/edgedb --tls-security=insecure migrate

5. Access the UI using the URL that was printed out when make deploy-local was running

   You will need to hit this URL at least once to ensure you have properly authenticated in. Afterwards you can access it via http://edgedb.127.0.0.1.nip.io:8080/ui

HTTP Server

Examples are here

Super Simple Example

package main

import (
	"fmt"
	"log"
	"net/http"

	cwhttp "github.com/CoverWhale/coverwhale-go/transports/http"
)

func testing(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("this works!"))
}

func main() {
	s := cwhttp.NewHTTPServer(
		cwhttp.SetServerPort(9090),
	)

	routes := []cwhttp.Route{
		{
			Method: http.MethodGet,
			Path: "/testing",
			Handler: http.HandlerFunc(testing)
		},
	}

	s.RegisterSubRouter("/api/v1", routes)
	log.Fatal(s.Serve())
}

Error Handlers

This library exposes an ErrHandler type that returns an error from the handlers. Client errors can easily be generated with the NewClientError function. This will automatically marshal the error value and return it to the caller. For example using an unauthorized error:

import (
	"github.com/CoverWhale/logr"	
	cwhttp "github.com/CoverWhale/coverwhale-go/transports/http"
)

var logger *logr.Logger

func myHandler(w http.ResponseWriter, r *http.Request) error {

	if r.Header.Get("Authorization") == "" {
		return cwhttp.NewClientError(fmt.Errorf("unauthorized"), http.StatusUnauthorized)
	}

	.../

}

var routes = []cwhttp.Route{
	{
		Method: http.MethodGet,
		Path: "/myhandler",
		Handler: &errHandler{
			Handler: myHandler,
			Logger: logger,
		},
	},
}

Handlers With a Struct Context

This library also exposes a HandleWithContext function. This allows for custom handlers to be created with a context value (not context.WithValue). For example passing a data source:

import (
	cwhttp "github.com/CoverWhale/coverwhale-go/transports/http"
)

var db *Database

func myHandler(w http.ResponseWriter, r *http.Request, db *Database) {
	id := chi.URLParam(r, "userId")
	user := db.GetUser(id)

	json.NewEncoder(w).Encode(user)
}

var routes = []cwhttp.Route{
	{
		Method: http.MethodGet,
		Path: "/users/{userId}",
		Handler: cwhttp.HandleWithContext(myHandler, db),
	},
}

Custom Handlers

To create custom handlers like above, you can just define your own type and implement the http.HandlerFunc similarly to how this library does:

type myHandlerType func(http.ResponseWriter, *http.Request, MyObject)

func myCustomHandlerType(h myHandlerType, obj MyObject) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		h(w, r, obj)
	}
}

func myHandler(w http.ResponseWriter, r *http.Request, obj MyObject) {
	obj.Do()
	.../
}

var routes = []cwhttp.Route{
	{
		Method: http.MethodGet,
		Path: "/testing",
		Handler: myCustomHandlerType(myHandler, obj),
	},
}