使用Makefile构建Docker

刚开始学习docker命令的时候，很喜欢一个字一个字敲，因为这样会记住命令。后来熟悉了之后，每次想要做一些操作的时候就不得不

重复的输入以前的命令。当切换一个项目之后，又重复输入类似但又不完全相同的命令，仅仅通过history命令加速也有限。

于是想，把要用的命令写到shell里，然后调用shell脚本去做。刚开始确实是这样做的。比如https://github.com/Ryan-Miao/docker-yapi。

直到有一天，发现有人使用Makefile来存储操作，瞬间感觉很棒。

这里简单记录Makefile的简单用法。

Makefile是什么

Makefile是make命令的规则配置文件。make命令是什么？

先来看看make在哪里

~ > whereis make
make: /usr/bin/make /usr/share/man/man1/make.1.gz

可以看到make是bin下的以可执行文件。看看用户手册

MAKE(1)                                                          User Commands                                                         MAKE(1)
NAME
       make - GNU make utility to maintain groups of programs
SYNOPSIS
       make [OPTION]... [TARGET]...
DESCRIPTION
       The  make  utility will determine automatically which pieces of a large program need to be recompiled, and issue the commands to recom‐
       pile them.  The manual describes the GNU implementation of make, which was written by Richard Stallman and Roland McGrath, and is  cur‐
       rently  maintained  by Paul Smith.  Our examples show C programs, since they are very common, but you can use make with any programming
       language whose compiler can be run with a shell command.  In fact, make is not limited to programs.  You can use  it  to  describe  any
       task where some files must be updated automatically from others whenever the others change.
       To prepare to use make, you must write a file called the makefile that describes the relationships among files in your program, and the
       states the commands for updating each file.  In a program, typically the executable file is updated from object  files,  which  are  in
       turn made by compiling source files.
       Once a suitable makefile exists, each time you change some source files, this simple shell command:
              make
       suffices  to  perform  all necessary recompilations.  The make program uses the makefile description and the last-modification times of
       the files to decide which of the files need to be updated.  For each of those files, it issues the commands recorded in the makefile.
       make executes commands in the makefile to update one or more target names, where name is typically a  program.   If  no  -f  option  is
       present, make will look for the makefiles GNUmakefile, makefile, and Makefile, in that order.
       Normally  you  should  call  your makefile either makefile or Makefile.  (We recommend Makefile because it appears prominently near the
       beginning of a directory listing, right near other important files such as README.)  The first name checked, GNUmakefile, is not recom‐
       mended for most makefiles.  You should use this name if you have a makefile that is specific to GNU make, and will not be understood by
       other versions of make.  If makefile is '-', the standard input is read.
       make updates a target if it depends on prerequisite files that have been modified since the target was last modified, or if the  target
       does not exist.

大致是说make是GNU中维护和组织程序的。比如我们的C语言编译，再比如源码安装某些软件，比如nginx的时候。那么GNU是什么鬼？

GNU(GNU's Not Unix)是一个类Unix系统，目标是创建一套完全自由的操作系统。在Linux出现之前，GNU已经完成了除了内核之外大部分的软件。Linux出现之后，与GNU结合变成GNU/Linux。

严格的说，Linux只代表Linux内核，其他Linux软件称为Linux发行版。但由于商业发行商坚持称呼Linux, 虽然已经更名为GNU/Linux, 但大家依然叫Linux.

## 比如我的本机Ubuntu
~ ❯ uname
Linux
~ ❯ uname -a
Linux ryan-computer 4.18.0-20-generic #21~18.04.1-Ubuntu SMP Wed May 8 08:43:37 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
## 大部分基于Debian的docker镜像
airflow@88e36c088b81:~$ cat /etc/issue
Debian GNU/Linux 9 \n \l
## RedHat
[root@data-docker001 docker-airflow]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
[root@data-docker001 docker-airflow]# uname -a
Linux data-docker001 3.10.0-693.2.2.el7.x86_64 #1 SMP Tue Sep 12 22:26:13 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

make的基本用法就是

make target

Makefile基本语法

详细参见附录参考，这里为了减少认知成本，只罗列用到的知识点。

在当前目录创建一个叫做Makefile的文件。

声明变量

简单的变量赋值，比如声明name

name=ryan

声明规则Rule

Makefile文件由一系列规则（rules）构成。每条规则的形式如下。

<target> : <prerequisites>
[tab]  <commands>

target 目标
prerequisites 前置条件
tab command必须由tab隔开
commands 只能有一行的shell

防止target和文件名一样

当我们设置的target和当前目录下的文件名一样的话，target会被忽略，所以，通常，我们把target都用做phony target。

.PHONY: build start push

表示， build start push 这3个target，不检查当前目录下的文件，直接执行命令。

Docker构建用的指令

我常用的Makefile如下

NAME = ryan/airflow
VERSION = 1.10.4
.PHONY: build start push
build:  build-version
build-version:
        docker build -t ${NAME}:${VERSION}  .
tag-latest:
        docker tag ${NAME}:${VERSION} ${NAME}:latest
start:
        docker run -it --rm ${NAME}:${VERSION} /bin/bash
push:   build-version tag-latest
        docker push ${NAME}:${VERSION}; docker push ${NAME}:latest

构建一个版本的镜像

make build

构建完毕，运行一下镜像，看看内容是否正确

make start

最后推送到docker仓库

make push

参考