โมดูล Go ด้วย go mod

โมดูล Go คืออะไร

// go.mod — created with: go mod init github.com/myuser/myapp
module github.com/myuser/myapp

go 1.21

require (
    github.com/gin-gonic/gin v1.9.1
    golang.org/x/sync v0.5.0
)

go mod init

# In project directory:
go mod init github.com/myuser/myapp

# This creates go.mod:
# module github.com/myuser/myapp
# go 1.21

# The module path is the canonical import path prefix
# for all packages in this module

go.sum — การตรวจสอบความถูกต้อง

# go.sum example entries:
github.com/gin-gonic/gin v1.9.1 h1:4idEAncQnU5cB7BeOkPtxjfCSye0AAm1R0RVIqJ+Jmg=
github.com/gin-gonic/gin v1.9.1/go.mod h1:hPrL7YrpYKXt5YId3A/Tnip5kqbEAP+KLuI3SUcPTeU=

# Commit go.sum to version control — it ensures reproducible builds

go get — การเพิ่มการพึ่งพา

# Add latest version
go get github.com/pkg/errors

# Add specific version
go get github.com/pkg/errors@v0.9.1

# Upgrade to latest patch release
go get -u=patch github.com/pkg/errors

# Remove unused dependency from go.mod
go mod tidy

go mod tidy

# After adding/removing imports:
go mod tidy

# What it does:
# 1. Adds any missing module requirements
# 2. Removes requirements for packages no longer imported
# 3. Updates go.sum with needed checksums
# 4. Best practice: run before committing

การกำหนดเวอร์ชันโมดูลด้วย Semver

// v1: github.com/pkg/errors
import "github.com/pkg/errors"

// v2+: module path includes major version
import "github.com/foo/bar/v2"
import "github.com/foo/bar/v3"

// go.mod:
// require github.com/foo/bar/v2 v2.3.1

go mod vendor

# Copy deps to vendor/
go mod vendor

# Build using vendor/
go build -mod=vendor ./...

# Useful for:
# - Air-gapped environments
# - Reproducible CI builds without network
# - Code review of dependencies

คำสั่ง replace

module github.com/myapp

go 1.21

require github.com/mylib v1.0.0

// Use local fork during development:
replace github.com/mylib => ../mylib

// Replace with a specific version:
// replace github.com/mylib v1.0.0 => github.com/myfork v1.0.0

go env GOPATH และ GOMODCACHE

# Module cache location (default: ~/go/pkg/mod)
go env GOMODCACHE

# Proxy for downloading modules (default: proxy.golang.org)
go env GOPROXY

# Sum database for checksum verification
go env GONOSUMCHECK

# Disable module proxy (use direct)
export GOPROXY=direct

go list และ go mod graph

# List all modules in the build
go list -m all

# Show module dependency graph
go mod graph

# Find which module provides a package
go list -m -json all | grep -A5 gin

# Check for available updates
go list -m -u all

ตรวจสอบอย่างรวดเร็ว

ทบทวน: โมดูล Go