golang-saas-starter-kit/internal/mid/panics.go

package mid

import (
	"context"
	"net/http"
	"runtime/debug"

	"geeks-accelerator/oss/saas-starter-kit/internal/platform/web"
	"github.com/pkg/errors"
	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
)

// Panics recovers from panics and converts the panic to an error so it is
// reported in Metrics and handled in Errors.
func Panics() web.Middleware {

	// This is the actual middleware function to be executed.
	f := func(after web.Handler) web.Handler {

		// Wrap this handler around the next one provided.
		h := func(ctx context.Context, w http.ResponseWriter, r *http.Request, params map[string]string) (err error) {
			span, ctx := tracer.StartSpanFromContext(ctx, "internal.mid.Panics")
			defer span.Finish()

			// Defer a function to recover from a panic and set the err return variable
			// after the fact. Using the errors package will generate a stack trace.
			defer func() {
				if r := recover(); r != nil {
					err = errors.Errorf("panic: %+v %s", r, string(debug.Stack()))
				}
			}()

			// Call the next Handler and set its return value in the err variable.
			return after(ctx, w, r, params)
		}

		return h
	}

	return f
}