GO SERVER

A template for Go servers. I found that I reuse some code everytime I write a go service. This is a starting point so I can clone and start new projects faster.

Background

It started when I was converting a ruby service to go. I wanted to write the minimum that gives me same ruby sinatra framework feeling without using a framework. for that I broke all community rules while writing this code but at the end it worked and felt good to achieve this result.

Features

• Compiles and embeds views from views directory
• Postgresql operations (create, drop, setup, seed, migrate up/down)
• Sinatra shorthand functions to define routes (GET, POST, DELETE)
• Session/Cookies
• Logging requests to STDOUT + response time
• Logging DB queries + execution time
• Method override with _method param.
• Sqlc setup for converting queries to go
• Docker and docker compose setups
• Deployment script
• Backup script

Dependencies

• Go
• Postgresql
• SQLc
• Docker, Docker-compose (if you want to deploy with docker)
• Sass
• wget
• unzip

Usage

• This is meant to be cloned
• Edit .env values and make sure it's loaded to your environment
• Edit the common.go constants.
• Generate database code with Sqlc bin/db setup
• Run bin/css to download and compile css and icons
• Use router gorilla router or GET, POST shorthand functions...etc.

Routes

common.go has couple functions to modify the http.Handler struct.

The most generic one is ROUTE which defines a function that gets executed if all RouteChecks functions are true.

func ROUTE(route http.HandlerFunc, checks ...RouteCheck)

RouteCheck function is a function that takes the request and returns true if the request should be executed with that handler function.

GET, POST, DELETE functions defined a route to a handler based on request path.

func GET(path string, handler HandlerFunc, middlewares ...func(http.HandlerFunc) http.HandlerFunc)
func POST(path string, handler HandlerFunc, middlewares ...func(http.HandlerFunc) http.HandlerFunc)
func DELETE(path string, handler HandlerFunc, middlewares ...func(http.HandlerFunc) http.HandlerFunc)

for example, this will match only the GET requests to / path and execute the function.

GET("/", func(w Response, r Request) Output {
    return Render("layout", "index", Locals{})
})

You can also pass middleware functions as the last parameter to execute them in order before the handler function.

Handler functions

The code started by a simple net/http.HandlerFunc but this interface doesn't have a return type. so to redirect and return for example that costs you two lines. to have more compact handler functions I created another interface

type HandlerFunc func(http.ResponseWriter, *http.Request) http.HandlerFunc

Which then can be converted to net/http.HandlerFunc itself using handlerFuncToHttpHandler function.

Also http.ResponseWriter and *http.Request are aliased to Response and Request so your function should look like so

func Users(w Response, r Request) Output {
  return Render("layout", "index", Locals{})
}

returned function Output is an alias to http.HandlerFunc and there are couple functions that can be used as return response like Redirect, Render, NotFound, BadRequest, Unauthorized, InternalServerError Redirect function for example is defined as follows

func Redirect(url string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		http.Redirect(w, r, url, http.StatusFound)
	}
}

Logging

Method Log can be used to log a line with label.

Log(DEBUG, "View", name)

Method LogDuration can be used to log execution time a colored label and a string. adding this line to a function will print something like

defer LogDuration(DEBUG, "View", name)()

LogDuration will return a function that when executed by defer it knows the time it was created an the time it's executed and will print that time difference + View label colored with DEBUG color and the value of name at the end.

16:30:39  View  (40.916µs) index

There are two colors defined so far DEBUG and INFO these are constants that defines shell escape characters for coloring the following text.

Views

views are .html files under views directory. they're embedded to the program with go embed package and parsed with html/template package before starting the server.

Rendering the view can be done using Render function as the example above.

Helpers

helper functions are passed while parsing the views files. you can use HELPER function to add more helpers. here is an example

// helper to check if list include a string
HELPER("include", func(list []string, str string) bool {
    for _, i := range list {
        if i == str {
            return true
        }
    }

    return false
})

Session

the code depends on gorilla/session . SESSION function returns an instance of the current request session.

Assets

bin/css is a shell script that will download bulma.io and fontawesome and compile them into one css file written under public/style.css and will copy fontawesome fonts to public/fonts.

public directory is served if there is no matching route for the request.

everytime you change bin/css or any css file that it imports you'll need to run it again to generate the new style.css file.

the layout include the style.css file and will compute the sha hash and include it as part of the url to force cache flushing when the file changes.

Running

All the code is in main package in this directory.

go generate // in case you changed db/query.sql
go run *.go

Deployment

a Dockerfile is included and docker-compose.yml to run a database, server and backup script containers.

• Edit variables in db/deploy
• Edit docker-compose.yml file to change volumes paths
• run bin/deploy master user@server to deploy master branch to server with ssh

Database

SQLX package is used and PQ package to connect to postgres database. the database URL is read from the environment.

bin/db is a shell script that include basic commands needed to manage database migrations. similar to rails db tasks. (create, seed, setup, migrate, rollback, dump schema, load schema, create_migration, drop database, reset). a small ~150 LOC.

If you don't need the database then remove:

• db directory
• bin/db file
• go generate line from common.go
• remove sqlx code from common.go

Backups

a shell script in bin/backup will run as a service on server to backup the database everyday.

Guidelines

• Respect no "best practice" unless there is a reason it's better for this code/server
• Reduce dependencies as much as possible
• Reduce code to the minimum
• All code is in main package no subpackages
• Should provide main features we're used to like db connection, migrations, logging. monitoring...etc