Docker环境使用cosmtrek/air时Go应用自动重载不触发重建问题

问题描述 #

Windows 10主机本地直接运行cosmtrek/air时可正常触发Go代码重建、完成热重载；将air部署到Docker容器运行后，进入容器确认挂载卷内的代码文件已随宿主机修改同步更新，但air始终不触发代码重建，也不输出新代码的运行日志，本地运行不存在该问题。

项目文件结构 #

-cmd
 -api
  -main.go
.air.toml
docker-compose.dev.yml
Dockerfile.dev
go.mod
go.sum

现有配置 #

Dockerfile.dev #

FROM golang:1.18.3-alpine3.15

WORKDIR /app

COPY go.mod go.sum /app/

RUN go mod download && go mod verify

RUN go install github.com/cosmtrek/air@latest

COPY ./ /app/

CMD "air"

docker-compose.dev.yml #

version: '3.8'
services:
  backend:
    container_name: go-backend-test
    build: 
      context: .
      dockerfile: ./Dockerfile.dev
    volumes:
      - ./:/app

.air.toml #

root = "."
testdata_dir = "testdata"
tmp_dir = "tmp"

[build]
  args_bin = []
  bin = "tmp/main.exe"
  cmd = "go build -o ./tmp/main.exe ./cmd/api/."
  delay = 1000
  exclude_dir = ["assets", "tmp", "vendor", "testdata"]
  exclude_file = []
  exclude_regex = ["_test.go"]
  exclude_unchanged = false
  follow_symlink = false
  full_bin = ""
  include_dir = []
  include_ext = ["go", "tpl", "tmpl", "html"]
  kill_delay = "0s"
  log = "build-errors.log"
  send_interrupt = false
  stop_on_error = true

[color]
  app = ""
  build = "yellow"
  main = "magenta"
  runner = "green"
  watcher = "cyan"

[log]
  time = false

[misc]
  clean_on_exit = true

[screen]
  clear_on_rebuild = true

容器运行日志 #

解决步骤 #

• 修正Linux环境下的二进制命名错误：当前基础镜像为Alpine Linux，可执行文件不需要.exe后缀，将.air.toml中bin = "tmp/main.exe"修改为bin = "tmp/main"，对应构建命令修改为cmd = "go build -o ./tmp/main ./cmd/api/."，避免二进制文件命名异常导致运行失败。
• 修复Docker跨系统挂载的文件事件丢失问题：Windows宿主机NTFS目录挂载到Linux容器时，系统原生inotify文件变更事件无法被容器内进程正常捕获，air默认依赖inotify触发构建，因此会出现文件已同步但不触发重建的现象。在.air.toml的[build]配置段添加如下参数，开启主动轮询模式监听文件变化：

  poll = true
  poll_interval = 500
  

  配置后air会每隔500ms主动扫描文件变更，不依赖系统inotify事件，可适配跨系统挂载卷场景。
• 优化挂载卷配置：在docker-compose.dev.yml的volumes配置中新增匿名卷挂载，将容器内的临时构建目录与宿主机隔离，减少不必要的文件同步开销，避免临时文件冲突：

  volumes:
    - ./:/app
    - /app/tmp
  

• 修正Dockerfile的CMD指令写法：将CMD "air"修改为CMD ["air"]，避免shell格式解析错误导致air启动时配置加载异常。

内容的提问来源于stack exchange，提问作者Vimal Kurien Sam