A Go function, end to end

A worked example: an endpoint that renders an HTML page from a template file, showing net/http routing, reading a static file, env vars, and the response helpers. It builds on the sdk-go/owly reference.

Scaffold

owly init --lang go portal
cd portal
owly add --lang go page --path /page

The handler

src/page/main.go:

package main

import (
	"net/http"
	"strings"

	"github.com/owly/owly-testing/sdk-go/owly"
)

func init() {
	http.HandleFunc("/page", func(w http.ResponseWriter, r *http.Request) {
		// Read the template from the project's public directory, with a fallback.
		template := "<h1>{{TITLE}}</h1><p>v{{VERSION}}</p>"
		if b, err := owly.Files.Get("page.html"); err == nil {
			template = string(b)
		}

		title := r.URL.Query().Get("title")
		if title == "" {
			title = "Portal"
		}
		html := strings.NewReplacer(
			"{{TITLE}}", title,
			"{{VERSION}}", owly.Env("APP_VERSION", "1.0.0"),
		).Replace(template)

		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		w.Write([]byte(html))
	})
}

func main() {}

Set the env var in owly.yaml:

functions:
  - name: page
    lang: go
    entrypoint: src/page/main.go
    path: /page
    env:
      APP_VERSION: "2.3.0"

A JSON API in the same project

owly add --lang go compute --path /compute, then src/compute/main.go:

package main

import (
	"net/http"
	"strconv"
	"time"

	"github.com/owly/owly-testing/sdk-go/owly"
)

func init() {
	http.HandleFunc("/compute", func(w http.ResponseWriter, r *http.Request) {
		n := 100_000
		if v := r.URL.Query().Get("n"); v != "" {
			if parsed, err := strconv.Atoi(v); err == nil && parsed > 0 {
				n = parsed
			}
		}

		start := time.Now()
		sum := 0
		for i := 0; i < n; i++ {
			sum += i % 7
		}

		owly.JSON(w, http.StatusOK, map[string]any{
			"iterations":  n,
			"checksum":    sum,
			"duration_ms": time.Since(start).Milliseconds(),
		})
	})
}

func main() {}

Run it

owly build
owly deploy
curl 'https://portal.<host>/page?title=Welcome'
curl 'https://portal.<host>/compute?n=500000'

What to take from this

• Stay net/http-native: register routes with http.HandleFunc in init().
• owly.Files.Get, owly.Env, and owly.JSON/owly.Text cover files, config, and responses without boilerplate.
• Handlers are request-scoped — read what you need per request (here the template) rather than relying on cross-request state. See Cold starts.
• Each function is its own package main under src/<name>/, mounted at its path from owly.yaml.