本文主要介绍如何将go项目打包成镜像,首先介绍Dockerfile常用命令介绍,然后介绍使用工具goctl用于生成Dockerfile,还可以根据需求自定义指令内容,最后讲解如何将go-blog项目打包成镜像,以及如何运行等

前言

参考文档:

开发完项目之后,可以通过dockerfile将项目打包成镜像

Dockerfile介绍

Dockerfile 是用于构建 Docker 镜像的文本文件,其中包含一系列指令(命令)。这些指令按照顺序执行,用于定义镜像的构建过程。下面是常用的 Dockerfile 命令及其详细解释:

  • FROM:指定基础镜像,用于构建当前镜像的基础。例如:FROM ubuntu:latest
  • LABEL:为镜像添加元数据,可以包含任意键值对。例如:LABEL maintainer="yourname@example.com"
  • RUN:在镜像中执行命令,并创建新的镜像层。例如:RUN apt-get update && apt-get install -y curl
  • CMD:指定容器启动时要执行的命令,该命令只能有一个。例如:CMD ["nginx", "-g", "daemon off;"]
  • EXPOSE:声明容器运行时监听的端口。例如:EXPOSE 8080
  • ENV:设置环境变量。例如:ENV MYSQL_VERSION 5.7
  • ADD:将文件、目录或远程 URL 的内容复制到镜像中。例如:ADD app.jar /app/
  • COPY:将文件或目录复制到镜像中。例如:COPY ./src /app/src
  • WORKDIR:设置工作目录,后续命令将在该目录下执行。例如:WORKDIR /app
  • VOLUME:声明持久化目录,用于在容器和主机之间共享数据。例如:VOLUME /data
  • ENTRYPOINT:指定容器启动时要执行的命令,与 CMD 不同的是,ENTRYPOINT 不会被Dockerfile 中的指令覆盖。例如:ENTRYPOINT ["java", "-jar", "app.jar"]
  • USER:设置运行后续命令的用户名或 UID。例如:USER myuser
  • ARG:定义构建参数,可以在构建镜像时通过 --build-arg 传递。例如:ARG VERSION=latest
  • ONBUILD:指定触发器命令,在当前镜像被继承时执行。例如:ONBUILD ADD . /app

下面是一个简单的示例,演示了如何编写一个用于构建基本 Go 应用程序的 Dockerfile。

# 使用官方的 Golang 镜像作为基础镜像
FROM golang:1.16

# 在容器内创建一个目录来存放我们的应用代码
RUN mkdir /app

# 将工作目录切换到 /app
WORKDIR /app

# 将当前目录下的所有文件拷贝到 /app 目录
COPY . .

# 编译 Go 应用程序
RUN go build -o myapp .

# 暴露 8080 端口
EXPOSE 8080

# 运行应用程序
CMD ["./myapp"]

当然还有更简便的方式,使用goctl工具生成Dockerfile,解放了生成力~

goctl工具生成Dockerfile

安装工具

 go install github.com/zeromicro/go-zero/tools/goctl@latest

命令行输入

(base) yangmiao@ym-mac gin-blog % goctl docker --help
Generate Dockerfile

Usage:
  goctl docker [flags]

Flags:
      --base string      The base image to build the docker image, default scratch (default "scratch")
      --branch string    The branch of the remote repo, it does work with --remote
      --exe string       The executable name in the built image
      --go string        The file that contains main function
  -h, --help             help for docker
      --home string      The goctl home path of the template, --home and --remote cannot be set at the same time, if they are, --remote has higher priority
      --port int         The port to expose, default none
      --remote string    The remote git repo of the template, --home and --remote cannot be set at the same time, if they are, --remote has higher priority
                         The git repo directory must be consistent with the https://github.com/zeromicro/go-zero-template directory structure
      --tz string        The timezone of the container (default "Asia/Shanghai")
      --version string   The goctl builder golang image version

在执行该命令后,Goctl 会自动生成一个名为 Dockerfile 的文件,包含适当的环境配置和基础镜像信息。

goctl docker --go main.go 

生成的Dockerfile文件如下所示

Dockerfile

多阶段构建

  • 第一个 FROM 开始的部分是构建一个 builder 镜像,目的是在其中编译出可执行文件 main
  • 第二个 From 开始的部分是从第一个镜像里 copy 出来可执行文件 main,并且用了基础镜像 scratch ,以保障最终镜像尽可能小
FROM golang:alpine AS builder

LABEL stage=gobuilder

ENV CGO_ENABLED 0
ENV GOPROXY https://goproxy.cn,direct
RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories

RUN apk update --no-cache && apk add --no-cache tzdata

WORKDIR /build

ADD go.mod .
ADD go.sum .
RUN go mod download
COPY . .
RUN go build -ldflags="-s -w" -o /app/main main.go


FROM scratch

COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
COPY --from=builder /usr/share/zoneinfo/Asia/Shanghai /usr/share/zoneinfo/Asia/Shanghai
ENV TZ Asia/Shanghai

WORKDIR /app
COPY --from=builder /app/main /app/main

CMD ["./main"]
  • 默认禁用了 cgo
  • 启用了 GOPROXY 加速 go mod download
  • 去掉了调试信息 -ldflags=“-s -w” 以减小镜像尺寸
  • 安装了 ca-certificates,这样使用 TLS证书就没问题了
  • tzdata 在 builder 镜像安装,并在最终镜像只拷贝了需要的时区
  • 自动设置了本地时区

构造镜像

至于docker如何使用,可以参考Docker-常用命令介绍,看这一篇就够了
在项目根目录下,执行docker build,用于生成镜像,生成镜像后就可以查看和启动了~

docker build -t go-blog:v1 .
(base) yangmiao@ym-mac gin-blog % docker build -t go-blog:v1 .
ERROR: Cannot connect to the Docker daemon at tcp://localhost:2375. Is the docker daemon running?
(base) yangmiao@ym-mac gin-blog % sudo docker build -t go-blog:v1 .
Password:
[+] Building 515.7s (18/18) FINISHED                                                                                                     
 => [internal] load build definition from Dockerfile                                                                                0.1s
 => => transferring dockerfile: 694B                                                                                                0.0s
 => [internal] load .dockerignore                                                                                                   0.1s
 => => transferring context: 2B                                                                                                     0.0s
 => [internal] load metadata for docker.io/library/golang:alpine                                                                  308.4s
 => [internal] load build context                                                                                                  10.3s
 => => transferring context: 215.37MB                                                                                              10.1s
 => [builder 1/9] FROM docker.io/library/golang:alpine@sha256:70afe55365a265f0762257550bc38440e0d6d6b97020d3f8c85328f00200dd8e    156.9s
 => => resolve docker.io/library/golang:alpine@sha256:70afe55365a265f0762257550bc38440e0d6d6b97020d3f8c85328f00200dd8e              0.0s
 => => sha256:86a63ed24dc22a348b35d99b5ec9dc67ff66563b539875e5c8ab2d870b3991ac 286.31kB / 286.31kB                                 75.8s
 => => sha256:ae48e6158ebb1a353f7d7b0676b0bd55a09a448a440b65135db378ffb0040919 64.09MB / 64.09MB                                  153.7s
 => => sha256:70afe55365a265f0762257550bc38440e0d6d6b97020d3f8c85328f00200dd8e 1.65kB / 1.65kB                                      0.0s
 => => sha256:635bf83d6a1993bf40e3c575d7b522d41950af4f1a5c1c7cd01c81d93b76f4bf 1.16kB / 1.16kB                                      0.0s
 => => sha256:1ddcbcaf7f02eab589ea6e5727ede30fe040922e4674737894898cddeaba40e0 6.34kB / 6.34kB                                      0.0s
 => => sha256:2c03dbb20264f09924f9eab176da44e5421e74a78b09531d3c63448a7baa7c59 3.33MB / 3.33MB                                     76.8s
 => => sha256:edabe92b0de78c4b662f63a4b2884d0821795e38a90c7ec070ccfa98f8aa236c 156B / 156B                                        151.3s
 => => extracting sha256:2c03dbb20264f09924f9eab176da44e5421e74a78b09531d3c63448a7baa7c59                                           0.8s
 => => extracting sha256:86a63ed24dc22a348b35d99b5ec9dc67ff66563b539875e5c8ab2d870b3991ac                                           0.1s
 => => extracting sha256:ae48e6158ebb1a353f7d7b0676b0bd55a09a448a440b65135db378ffb0040919                                           2.6s
 => => extracting sha256:edabe92b0de78c4b662f63a4b2884d0821795e38a90c7ec070ccfa98f8aa236c                                           0.0s
 => [builder 2/9] RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories                                  1.0s
 => [builder 3/9] RUN apk update --no-cache && apk add --no-cache tzdata                                                            2.7s
 => [builder 4/9] WORKDIR /build                                                                                                    0.0s
 => [builder 5/9] ADD go.mod .                                                                                                      0.0s
 => [builder 6/9] ADD go.sum .                                                                                                      0.0s
 => [builder 7/9] RUN go mod download                                                                                              14.2s
 => [builder 8/9] COPY . .                                                                                                          7.4s
 => [builder 9/9] RUN go build -ldflags="-s -w" -o /app/main main.go                                                               24.5s
 => [stage-1 1/4] COPY --from=builder /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt                         0.0s
 => [stage-1 2/4] COPY --from=builder /usr/share/zoneinfo/Asia/Shanghai /usr/share/zoneinfo/Asia/Shanghai                           0.0s
 => [stage-1 3/4] WORKDIR /app                                                                                                      0.0s
 => [stage-1 4/4] COPY --from=builder /app/main /app/main                                                                           0.1s
 => exporting to image                                                                                                              0.1s
 => => exporting layers                                                                                                             0.1s
 => => writing image sha256:556e5362b86a63c8d1325549b595d987c8c79ad749524875c9d018c44cbf3ad5                                        0.0s
 => => naming to docker.io/library/go-blog:v1                                                                                       0.0s

查看镜像:

sudo docker images | grep go-blog

在这里插入图片描述

启动镜像:

 sudo docker run -it go-blog:v1
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