Serving HTTP requests using a Go binary file and Supervisor in Ubuntu

Go builds everything into a single binary file, making deployment easier. However, it's not feasible to keep the terminal open to run the Go file forever. Supervisor comes to the rescue by managing the process for us!

Prepare in the local machine

Firstly, we create a basic Go hello file that serves HTTP requests. We will run it on port 8000 or any other port given by the environment variable.

package main

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

func main() {
	port := os.Getenv("PORT")
	if port == "" {
		port = "8000"
	}

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		w.Write([]byte(fmt.Sprintf("Hello from port %s", port)))
	})

	fmt.Printf("Listening on :%s\n", port)
	http.ListenAndServe(fmt.Sprintf(":%s", port), nil)
}

Build the binary file, please make sure to add the two environment variables to build for Linux. Otherwise, it will build the wrong binary. By default Go will build the binary file for the current operating system (in my case is MacOS).

GOOS=linux GOARCH=amd64 go build -o hello_bin hello.go

Copy the built binary file hello_bin to the server's /home/ubuntu/hello folder. I recommend using rsync instead of scp because it offers better performance and can handle file and folder copying, updating old files, and creating new folders if they don't exist, all in a single command 🚀.

rsync -avz ./hello_bin ubuntu@159.223.47.97:/home/ubuntu/hello

Go to remote Ubuntu server

Go to our Ubuntu remote server:

ssh ubuntu@159.223.47.97 #change to your user and server IP

Please install Supervisor if it is not already installed.

sudo apt update && sudo apt install supervisor

Let's create a Supervisor configuration file called hello1.conf. You can use either vim or nano to create or edit the file.

sudo vim /etc/supervisor/conf.d/hello1.conf

Please be noted to use the full path for the command key, rather than a relative path from the current directory.

[program:hello1]
command=/home/ubuntu/hello/hello_bin
directory=/home/ubuntu/hello
user=ubuntu
autostart=true
autorestart=true
stderr_logfile=/var/log/hello1.err.log
stdout_logfile=/var/log/hello1.out.log

Similarly, let's create a program configuration file called hello2.conf. This file should include the environment variable PORT=8001 so that later we can run our two programs simultaneously on different ports.

sudo vim /etc/supervisor/conf.d/hello2.conf

[program:hello2]
command=/home/ubuntu/hello/hello_bin
directory=/home/ubuntu/hello
user=ubuntu
autostart=true
autorestart=true
stderr_logfile=/var/log/hello2.err.log
stdout_logfile=/var/log/hello2.out.log
environment=PORT=8001

Now, let's update the Supervisor with the new configuration. Let's use the supervisorctl reread command for two purposes:

• to help Supervisor review new information (without changing the configuration)
• and to check if our newly added configurations are valid before performing the actual update.

sudo supervisorctl reread
# hello1: available
# hello2: available

Next, we perform the actual update in configuration state of Supervisor. After update the programs are ready to run.

sudo supervisorctl update

Now, we can run our programs using either the start or restart command. It is okay to simply use restart as if the program already run we will get a small error but it still work properly.

sudo supervisorctl restart hello1
# hello1: ERROR (not running) # you see it when the program has never run and it is FINE
# hello1: started

Do the same for hello2:

sudo supervisorctl restart hello2
# hello2: stopped # you see it when the program is currently running
# hello2: started

Moment of Truth

Go back to our Local machine to test our two programs hello1 and hello2:

curl http://159.223.47.97:8000/
# Hello from port 8000

curl http://159.223.47.97:8001/
# Hello from port 8001

Great! We can see that hello2 is receiving the PORT environment variable and running properly.

We've done now!

Bonus

To group hello1 and hello2 together for easier management, you can modify the /etc/supervisor/conf.d/hello2.conf file by adding two additional lines at the end.

[program:hello2]
command=/home/ubuntu/hello/hello_bin
directory=/home/ubuntu/hello
user=ubuntu
autostart=true
autorestart=true
stderr_logfile=/var/log/hello2.err.log
stdout_logfile=/var/log/hello2.out.log
environment=PORT=8001

[group:hello]
programs=hello1,hello2

Now, we can run the group hello: (note the colon :) to manage both hello1 and hello2 together.

sudo supervisorctl reread
sudo supervisorctl update
sudo supervisorctl restart hello:

Please note that you can no longer directly interact with the individual processes hello1 and hello2. Instead, you will need to use the hello group to manage them. Running individual program is error now:

sudo supervisorctl restart hello1
# hello1: ERROR (no such process)

We must do this instead:

sudo supervisorctl restart hello:
# hello:hello1: stopped
# hello:hello2: stopped
# hello:hello1: started
# hello:hello2: started

Source code: https://gist.github.com/anvodev/19c1402b93258bb4272ecf4dd64ba6bc

Thanks for reading! Good luck with the server-related tasks!