Managing Dependencies

A Go dependency is another module your project uses. Go tooling resolves versions and keeps module metadata consistent.

go get example.com/lib@version changes the required module version; go mod tidy adds needed and removes unneeded requirements and sums. go list -m all reports the selected module graph when supported by the graph and environment.

For reproducible builds, commit both module metadata files and review dependency upgrades. Prefer specific version tags rather than assuming that a latest version has identical behavior. External modules should be reviewed for licenses, maintenance and security.

Follow this diagram before executing the example. Check where a value or decision changes what runs next.

Dependency workflow

go get example.com/some/library@v1.2.3
go mod tidy
go test ./...
go list -m all

The module path/version shown is illustrative, not a real package to fetch.

This example is a complete program. Save it as main.go or paste it into the Go Playground.

Go code

package main

import (
	"fmt"
	"strings"
)

func main() {
	modules := []string{"resolve", "verify", "build"}
	fmt.Println(strings.Join(modules, " -> "))
}

Output

resolve -> verify -> build

The steps printed by this standard-library-only example summarize the main workflow. Actual dependency resolution occurs when running the go commands, not inside main.

• go get updates dependencies; it does not execute your program.
• Do not use wildcard updates without reviewing version changes.

Run go list -m all, go mod tidy, and compare the repository diff before accepting an upgrade.

Tip: Edit the example above, predict the output, and run the modified code to test your reasoning.

You have practiced Managing Dependencies in a small, self-contained program. The important habit is to predict what runs, inspect the actual output and distinguish the language rule from the particular example.

Before continuing, make sure you can explain the program to someone who has not seen it, including the line that changes its result.