How to deploy a Go app.

The short answer

To deploy a Go app, give your coding agent the sentence below. Antideploy finds go.mod, builds your program into one binary, and runs it. You do not write a start command. Your code must listen on the port in the PORT variable, and on all addresses. For Go projects, Antideploy uses port 8080.

What Antideploy detects

• Go. Detected from go.mod at the root of what you send.
• The start command. Antideploy does not add one. Go compiles to a single binary, and the build sets the entrypoint from what it produced.
• The port. It sends traffic to port 8080 and sets PORT to match.
• The database. If your code needs Postgres, Antideploy creates one and sets DATABASE_URL and the PG* variables.

A small Go server

package main

import (
	"context"
	"fmt"
	"net/http"
	"os"

	"github.com/jackc/pgx/v5/pgxpool"
)

func main() {
	port := os.Getenv("PORT")
	if port == "" {
		port = "8080"
	}

	pool, err := pgxpool.New(context.Background(), os.Getenv("DATABASE_URL"))
	if err != nil {
		panic(err)
	}
	defer pool.Close()

	http.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprint(w, "ok")
	})

	http.ListenAndServe(":"+port, nil)
}

Listening on ":" + port means all addresses, which is what a server needs. Do not use "localhost:" + port.

Step by step

1. Check the module

   go.mod and go.sum are committed. Run go mod tidy if you added a package.

2. Paste the sentence and approve one link

   Your agent creates the app, and a database if your code needs one, and writes the connection details into your .env without printing them.

3. Deploy and open the link

   Antideploy builds the binary, starts it and checks that it answers. Your agent tells you the address.

Common problems

• go.sum is incomplete. The build says missing go.sum entry or updates to go.mod needed. Run go mod tidy on your machine and commit go.mod and go.sum.
• The program does not compile. The deploy names the error, such as an undefined name.
• The app never starts listening. It uses a fixed port, or localhost. Read PORT and listen on all addresses. See never started listening.