Start With the Go Standard Library

- 13 mins read

When starting a project, new Gophers often ask the following questions.

  • What logger should I use?
  • What web framework should I use?
  • What object–relational mapping (ORM) should I use?

These questions are well-intentioned but they all miss a key aspect about Go.

Go has a great standard library.

Let’s understand why.

What is a Standard Library?

A standard libary is library of packages that are included with a programming language. These packages can be used without downloading additional source code.

For example, the following hello world program uses the fmt package from the Go standard library.

package main

import (
	"fmt" // Imported from the Go standard library.
)

func main() {
	fmt.Println("Hello, world!")
}

You can run this program like so.

> go run .
Hello, world!

Contrast this with the following hello world program that uses the third-party github.com/fatih/color package.

package main

import (
	"github.com/fatih/color" // Imported from the downloaded source code.
)

func main() {
	// Prints `Hello, world!` in bold red.
	c := color.New(color.FgRed).Add(color.Bold)
	c.Println("Hello, world!")
}

Since the github.com/fatih/color package is not in the Go standard library, you must download its source code and all its dependencies before it can be used.

> go run .
go: downloading github.com/fatih/color v1.16.0
go: downloading github.com/mattn/go-colorable v0.1.13
go: downloading github.com/mattn/go-isatty v0.0.20
go: downloading golang.org/x/sys v0.14.0
Hello, world!

Documentation for both the Go standard library and third-party packages can be found at pkg.go.dev.

Why Start With the Go Standard Library?

When deciding whether to use the Go standard library or a third-party package, one might think the decision comes down to the quality of the package. While quality is a factor, generally speaking, there isn’t much of a quality difference between the Go standard library and well-written, well-maintained third-party packages.

Determining the quality of a package can be both objective and subjective depending on the metric being measured. Luckily there are many resources out there to help you, including the popular OpenSSF Scorecard.

Quality aside, I recommend new Gophers start with the Go standard library for the following reasons.

  • Stability - The stability of the Go standard library is in its name— standard. The Go standard library exposes a standard set of APIs that rarely change, making them a great candidate for building higher level abstractions. Combine that with Go’s Backward Compatibility and the stability of the Go standard library really shines.
  • Extensibility - The Go standard library is quite extensive. There are packages for logging, interacting with the OS, communicating over the network, and much more. The Go standard library also exposes interfaces such as io.Reader that programs can implement to provide custom behavior that’s compatible with standard library APIs.
  • Maintainability - The best code is the code that you can use but don’t have to maintain. The Go standard library is maintained by engineers that are paid to work on Go. This means you don’t have to worry about a package in the standard library being out of date or incompatible with your version of Go.
  • No Dependencies - You don’t have to download additional source code to use the Go standard library, it’s already there with your installation of Go. This means fewer dependencies in your code which can lead to quicker CI/CD build times and fewer security vulnerabilities.
  • Reduced Lock-In - Many third-party packages maintain API compatibility with the Go standard library. Others don’t. Using the Go standard library can make it easier to migrate from the standard library to compatible third-party packages and vice versa.

The Go Standard Library vs. Third-Party Packages

Now that we have a better understanding of the Go standard library let’s answer some of those questions that new Gophers tend to ask.

We’ll use a question-driven approach, comparing the Go standard library to third-party packages.

What Logger Should I Use?

Standard library:

Third-party packages:

Prior to Go 1.21 the standard library only had the log package, which did not support log levels or structured logging. For those unfamiliar, structured logging is the ability to log information in a machine-readable format that can be parsed by your favorite log aggregation tool. Usually structured logs are emitted using JSON syntax and contain key-value pairs of information.

Since the log package doesn’t support log levels or structured logging, third-party packages became the primary way to log in Go. In Go 1.21, the log/slog package was introduced with support for log levels and structured logging. I recommend new Gophers start with log/slog for their logging needs.

This code example shows the API differences between log, log/slog, and go.uber.org/zap.

package main

import (
	"log"
	"log/slog"
	"os"

	"go.uber.org/zap"
)

const (
	// Simulate information from an HTTP request.
	method = "GET"
	path   = "/api/v1/users"
)

func main() {
	// log
	stdLog := log.New(os.Stdout, "", log.LstdFlags)
	stdLog.Printf("request received: method=%s path=%s", method, path)

	// log/slog
	stdSLog := slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{}))
	stdSLog.Info("request received:",
		"method", method,
		"path", path,
	)

	// go.uber.org/zap
	zapLogger, _ := zap.NewProduction()
	defer zapLogger.Sync()
	zapLogger.Info("request received:",
		zap.String("method", method),
		zap.String("path", path),
	)
}

This code example highlights the log package’s lack of support for key-value pairs when compared to log/slog and go.uber.org/zap.

Running the code shows how different the log output is from the log/slog and go.uber.org/zap output.

> go run .
2024/02/04 22:20:03 request received: method=GET path=/api/v1/users
{"time":"2024-02-04T22:20:03.140393797-05:00","level":"INFO","msg":"request received:","method":"GET","path":"/api/v1/users"}
{"level":"info","ts":1707103203.1404333,"caller":"helloworld/main.go:32","msg":"request received:","method":"GET","path":"/api/v1/users"}

What Web Framework Should I Use?

Standard library:

Third-party packages:

This question can be difficult to answer, especially for engineers coming from web frameworks like Next.js, Laravel, Django, Ruby on Rails, etc. Go doesn’t have a web framework as extensive as those from other languages. The closest you’ll find is github.com/gobuffalo/buffalo, but even that isn’t as featureful as something like Ruby on Rails.

Instead of a web framework, Go encourages you to choose an HTTP multiplexer and extend it as needed. That’s why the list of third-party packages above is primarily filled with HTTP multiplexers instead of web frameworks. Want to use net/http with React? Sure thing! How about github.com/go-chi/chi with Go templates? Go for it! The truth is it doesn’t matter much what HTTP multiplexer you use, so choose the one that you’re most familiar with and can get help with when needed.

I recommend new Gophers running Go 1.22 or later start with net/http for their HTTP multiplexing needs. In Go 1.22, the net/http package received major quality of life updates such as the ability to register an HTTP handler with an HTTP method and the ability to use and retrieve URL path variables. These updates make the net/http package an attractive choice compared third-party packages.

Prior to Go 1.22, the net/http package didn’t support these features, making third-party packages the popular route (pun intended) for Gophers. If you’re working on a project that isn’t on Go 1.22 or later then I recommend choosing a third-party package for your HTTP multiplexing needs. I personally like github.com/go-chi/chi, but github.com/labstack/echo and github.com/gofiber/fiber are also popular choices, especially for those familiar with Express.

This code example shows the API differences between Go 1.22’s net/http, github.com/go-chi/chi, and github.com/labstack/echo.

package main

import (
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"os/signal"
	"syscall"

	"github.com/go-chi/chi"
	"github.com/labstack/echo"
)

type Response struct {
	ID      string `json:"id"`
	HTTPMux string `json:"http_mux"`
}

func main() {
	// net/http
	stdMux := http.NewServeMux()
	stdMux.HandleFunc("GET /api/v1/{id}", func(w http.ResponseWriter, r *http.Request) {
		id := r.PathValue("id")
		resp := Response{ID: id, HTTPMux: "net/http"}
		if err := json.NewEncoder(w).Encode(resp); err != nil {
			// Handle error.
		}
	})

	// github.com/go-chi/chi
	chiMux := chi.NewMux()
	chiMux.Get("/api/v1/{id}", func(w http.ResponseWriter, r *http.Request) {
		id := chi.URLParam(r, "id")
		resp := Response{ID: id, HTTPMux: "github.com/go-chi/chi"}
		if err := json.NewEncoder(w).Encode(resp); err != nil {
			// Handle error.
		}
	})

	// github.com/labstack/echo
	echoMux := echo.New()
	echoMux.GET("/api/v1/:id", func(ctx echo.Context) error {
		id := ctx.Param("id")
		resp := Response{ID: id, HTTPMux: "github.com/labstack/echo"}
		return ctx.JSON(http.StatusOK, resp)
	})

	// Start all three HTTP multiplexers asynchronously.
	for i, mux := range []http.Handler{stdMux, chiMux, echoMux} {
		go func(portOffset int, mux http.Handler) {
			server := http.Server{
				Addr:    fmt.Sprintf(":%d", 3000+portOffset),
				Handler: mux,
			}
			fmt.Printf("Listening on %s...\n", server.Addr)
			_ = server.ListenAndServe()
		}(i, mux)
	}

	shutdown := make(chan os.Signal, 1)
	signal.Notify(shutdown, syscall.SIGTERM, syscall.SIGINT)

	fmt.Println("Press Ctrl+C to stop.")
	<-shutdown
}

I know that’s a lot of code, but I wanted you to see that there are minimal API differences across packages. They all support URL path variables and follow the same basic structure to create HTTP handlers. The noteworthy differences are:

  • net/http registers an HTTP handler with an HTTP method by specifying the HTTP method within HandleFunc (e.g., HandleFunc("GET /foo", ...)). The other packages expose specific .GET, .POST, etc. methods for this.
  • github.com/labstack/echo does not use the http.HandlerFunc function signature from the Go standard library. Instead it uses a custom function signature that returns an error, which can make error handling easier at the cost of API compatibility with the Go standard library.

If you’re running Go 1.22, you can run this code like so.

> go run .
Listening on :3001...
Listening on :3000...
Listening on :3002...
Press Ctrl+C to stop.

Note: Ensure your go.mod file contains go 1.22 or later otherwise Go will use the older Go 1.21 and earlier net/http behavior.

From another terminal you can connect to each endpoint to see its response.

> curl http://localhost:3000/api/v1/1337
{"id":"1337","http_mux":"net/http"}

> curl http://localhost:3001/api/v1/1337
{"id":"1337","http_mux":"github.com/go-chi/chi"}

> curl http://localhost:3002/api/v1/1337
{"id":"1337","http_mux":"github.com/labstack/echo"}

What Object–Relational Mapping (ORM) Should I Use?

Standard library:

Third-party packages:

This question can also be difficult to answer, especially if engineers have strong opinions about writing SQL. I’ve witnessed many engineers spend more debating this question than building their application.

Before I answer this question let’s define what an object-relational mapping is. An object-relational mapping is a way to map objects in a programming language (i.e., Go structs) into database relations (i.e., tables) and vice versa.

For example, an object-relational mapping takes the following Go struct.

type Avenger struct {
  ID   int 
  Name string
  Age  int
}

And maps its fields to the columns in the following database table.

CREATE TABLE avengers (
    id SERIAL,
    name TEXT NOT NULL,
    age INT NOT NULL,

    PRIMARY KEY (id)
);

This allows you to interact with your database from your code without needing to understand how to serialize and deserialize the raw bytes to and from the database.

Like most terms in the technology industry, object-relational mapping is overloaded. Most programming languages have functionality in their standard library to interact with a database using a database driver and raw SQL queries. Isn’t that an object-relational mapping? Not quite. An object-relational mapping extends and abstracts the standard library APIs, providing a new API using the programming language itself without the engineer needing to write any SQL. In practice it looks something like this.

Database interaction using the standard library.

type Avenger struct {
	ID   int
	Name string
	Age  int
}

row := db.QueryRow("SELECT * FROM avengers WHERE id = 1")
if err := row.Err(); err != nil {
	// Handle error.
}

var a Avenger
if err := row.Scan(&a.ID, &a.Name, &a.Age); err != nil {
	// Handle error.
}

Database interaction using an object-relational mapping.

type Avenger struct {
	gorm.Model

	ID   int
	Name string
	Age  int
}

var a Avenger
result := db.First(&a, 1)
if err := Result.Error; err != nil {
	// Handle error.
}

The standard library interaction:

  • Requires you to write the raw SQL query
  • Scans individual database columns into Go variables
  • Does not modify your Go struct type

In contrast, the object-relational mapping interaction:

  • Abstracts away the raw SQL query
  • Scans database columns as a group into a Go struct
  • Modifies your Go struct type with an embedded type

As an engineer you’ll have to weigh these considerations and decide which approach is best for you. I recommend new Gophers start with either database/sql or github.com/jmoiron/sqlx for their database needs. They both have a simple API and allow you to write SQL queries, which is a great skill to have as an engineer. Even though database/sql requires you to scan database columns individually, it’s more explicit and can help prevent cases where some columns weren’t scanned successfully. As your project grows you can decide if migrating to an object-relational mapping such as gorm.io/gorm is worth it.

Alternatively, you can check out github.com/sqlc-dev/sqlc which is somewhat in between the standard library and an object-relational mapping. While some people call this an object-relational mapping, it’s really more of a code generation tool that takes raw SQL queries and builds the necessary Go structs and functions. It’s quite a useful tool that I’ve used in production at a few companies.

I know that was a lot of content. A code example might help you compare database/sql, github.com/jmoiron/sqlx, and gorm.io/gorm for yourself.

First, you’ll need a database. Let’s create a Marvel themed PostgreSQL database using a container.

podman run --rm --detach \
    --name shield_db \
    --env POSTGRES_USER=fury \
    --env POSTGRES_PASSWORD=fury \
    --env POSTGRES_DB=shield \
    --publish 5432:5432 \
    postgres:16

Note: Substitute podman with docker if you’re using Docker.

Create a seed.sql file with the following content. We’ll use this to create our database table and insert some data into it.

CREATE TABLE avengers (
    id SERIAL,
    name TEXT NOT NULL,
    age INT NOT NULL,

    PRIMARY KEY (id)
);

INSERT INTO avengers (
    name, age
) VALUES
    ('Steve Rogers', 105),
    ('Tony Stark', 53);

Run the seel.sql file to create the database table and insert some data into it.

> podman exec -i shield_db psql -U fury -d shield < seed.sql
CREATE TABLE
INSERT 0 2

This code example shows the API differences between database/sql, github.com/jmoiron/sqlx, and gorm.io/gorm.

package main

import (
	"database/sql"
	"fmt"

	"github.com/jmoiron/sqlx"
	_ "github.com/lib/pq"     // PostgreSQL database driver for sql and sqlx.
	"gorm.io/driver/postgres" // PostgreSQL database driver for gorm.
	"gorm.io/gorm"
)

const (
	dbDriver = "postgres"
	dbURL    = "postgres://fury:fury@localhost:5432/shield?sslmode=disable"
)

type Avenger struct {
	ID   int    `db:"id"`
	Name string `db:"name"`
	Age  int    `db:"age"`
}

func main() {
	// database/sql
	a1, err := runStdDB()
	if err != nil {
		// Handle error.
	}

	// github.com/jmoiron/sqlx
	a2, err := runSqlxDB()
	if err != nil {
		// Handle error.
	}

	// gorm.io/gorm
	a3, err := runGormDB()
	if err != nil {
		// Handle error.
	}

	fmt.Printf("database/sql:\n\t%v\n", a1)
	fmt.Printf("github.com/jmoiron/sqlx:\n\t%v\n", a2)
	fmt.Printf("gorm.io/gorm:\n\t%v\n", a3)
}

// database/sql
func runStdDB() (*Avenger, error) {
	stdDB, err := sql.Open(dbDriver, dbURL)
	if err != nil {
		return nil, err
	}
	defer stdDB.Close()

	row := stdDB.QueryRow("SELECT * FROM avengers WHERE id = 1")
	if err := row.Err(); err != nil {
		return nil, err
	}

	var a Avenger
	if err := row.Scan(&a.ID, &a.Name, &a.Age); err != nil {
		return nil, err
	}

	return &a, nil
}

// github.com/jmoiron/sqlx
func runSqlxDB() (*Avenger, error) {
	sqlxDB, err := sqlx.Open(dbDriver, dbURL)
	if err != nil {
		return nil, err
	}
	defer sqlxDB.Close()

	var a Avenger
	if err := sqlxDB.Get(&a, "SELECT * FROM avengers WHERE id = 1"); err != nil {
		return nil, err
	}

	return &a, nil
}

// gorm.io/gorm
func runGormDB() (*Avenger, error) {
	gormDB, err := gorm.Open(postgres.Open(dbURL), &gorm.Config{})
	if err != nil {
		return nil, err
	}
	defer func() {
		db, _ := gormDB.DB()
		db.Close()
	}()

	var a Avenger
	result := gormDB.First(&a, 1)
	if err := result.Error; err != nil {
		return nil, err
	}

	return &a, nil
}

I’ve already detailed some of the differences between these packages earlier, but you can see how the SQL query and scanning gets more abstracted as you move away from database/sql and towards gorm.io/gorm.

Go ahead and run this code to see the output.

> go run .
database/sql:
        &{1 Steve Rogers 105}
github.com/jmoiron/sqlx:
        &{1 Steve Rogers 105}
gorm.io/gorm:
        &{1 Steve Rogers 105}

When you’re finished, stop and remove the running PostgreSQL container.

> podman rm -f shield_db
shield_db

Final Thoughts

Thank you for reading the entire post to completion. I know that was a lot of content, but I hope you enjoyed it and learned more about Go.

We covered what a standard library is, why you should start with the Go standard library, and compared the Go standard library with third-party packages. I hope you were able to see just how great the Go standard library is, especially with the changes in Go 1.22.

Next time you have questions about which package to use for your Go project, take the time to research whether the Go standard library has a package that meets your needs. I suspect you’ll find a package that does meet your needs and you’ll agree when I say:

Go has a great standard library.

Actually, I’ll take that one step further and end this post with:

Go has a great standard library, and you should start with it.