浅谈GIT之通讯协议

Posted 2021-03-12 jayhou

一、基本概述

git目前支持4种的通讯协议：本地协议(Local)、ssh、http(Dumb哑协议和Smart智能协议)和Git协议

1.1、本地协议介绍

本地协议是基于本地文件系统或者共享的文件系统进行访问，也就是说远程版本库就是硬盘中另外的一个目录。

因此搭建起来就特别容易，可以完成代码的版本管理。适合临时搭建使用。

以下代码做演示

首先我在e盘创建一个共享文件夹git_repo,然后创建一个裸仓库做交互

1 ##
2 hjjie@mrforever MINGW64 /e
3 $ cd git_repo/
4 
5 hjjie@mrforever MINGW64 /e/git_repo
6 $ git init --bare share.git
7 Initialized empty Git repository in E:/git_repo/share.git/

然后我在另外一个文件夹中clone空项目下来，并放入一个文本文件，然后git add -》git commit -》git push,提交代码到共享文件夹

 1 hjjie@mrforever MINGW64 /e/git_study
 2 $ git clone /e/git_repo/share.git/
 3 Cloning into ‘share‘...
 4 warning: You appear to have cloned an empty repository.
 5 done.
 6 
 7 hjjie@mrforever MINGW64 /e/git_study
 8 $ cd share/
 9 
10 hjjie@mrforever MINGW64 /e/git_study/share (master)
11 $ echo ‘hello git‘ > git.txt; git add -A; git commit -am ‘first commit‘; git push;
12 warning: LF will be replaced by CRLF in git.txt.
13 The file will have its original line endings in your working directory.
14 [master (root-commit) cea04b4] first commit
15  1 file changed, 1 insertion(+)
16  create mode 100644 git.txt
17 Counting objects: 3, done.
18 Writing objects: 100% (3/3), 207 bytes | 0 bytes/s, done.
19 Total 3 (delta 0), reused 0 (delta 0)
20 To E:/git_repo/share.git/
21  * [new branch]      master -> master

当然，除了直接访问外，还可以通过file协议进行访问 git clone file:///e/git_repo/share.git/ 

1 hjjie@mrforever MINGW64 /e/git_study2
2 $ git clone file:///e/git_repo/share.git/
3 Cloning into ‘share‘...
4 remote: Counting objects: 3, done.
5 remote: Total 3 (delta 0), reused 0 (delta 0)
6 Receiving objects: 100% (3/3), done.

这样子，会将相关资源打包再传输过来，在传输过来的仓库中会发现打包后的文件

1.2、SSH协议(Secure SHell)

git本身支持ssh协议，而且利用ssh协议搭建git服务器也很简单，ssh协议访问也是很高效安全，

只是在linux系统上直接使用这样裸的Git服务，本身权限方面就比较不灵活，因为需要依赖Linux自身的访问权限

在Linux服务器上安装Git可以看这里：

以下是演示的过程：

首先在Linux上初始化一个裸仓库

1 [root@service103 apps]# mkdir git-repo
2 [root@service103 apps]# ls
3 git  git-repo  jdk1.8  pack
4 [root@service103 apps]# cd git-repo/
5 [root@service103 git-repo]# git init --bare remote.git
6 Initialized empty Git repository in /apps/git-repo/remote.git/
7 [root@service103 git-repo]# 

然后在本地尝试clone  git clone root@192.1.1.103:/apps/git-repo/remote.git 并加入文本然后git add -》 git commit -》 git push

 1 hjjie@mrforever MINGW64 /e/git_study
 2 $ git clone root@192.1.1.103:/apps/git-repo/remote.git
 3 Cloning into ‘remote‘...
 4 The authenticity of host ‘192.1.1.103 (192.1.1.103)‘ can‘t be established.
 5 ECDSA key fingerprint is SHA256:SNb2t6iAVaQuHd1FvOdB2lPSVASbU07i8raTpllD0aE.
 6 Are you sure you want to continue connecting (yes/no)? yes
 7 Warning: Permanently added ‘192.1.1.103‘ (ECDSA) to the list of known hosts.
 8 root@192.1.1.103‘s password:
 9 warning: You appear to have cloned an empty repository.
10 
11 hjjie@mrforever MINGW64 /e/git_study
12 $ ls
13 remote/  share/
14 
15 hjjie@mrforever MINGW64 /e/git_study
16 $ cd remote/
17 
18 hjjie@mrforever MINGW64 /e/git_study/remote (master)
19 $ echo ‘hello git‘ > git.txt;
20 
21 hjjie@mrforever MINGW64 /e/git_study/remote (master)
22 $ git add -A; git commit -am ‘first ssh commit‘; git push;
23 warning: LF will be replaced by CRLF in git.txt.
24 The file will have its original line endings in your working directory.
25 [master (root-commit) 4f831ab] first ssh commit
26  1 file changed, 1 insertion(+)
27  create mode 100644 git.txt
28 root@192.1.1.103‘s password:
29 Counting objects: 3, done.
30 Writing objects: 100% (3/3), 210 bytes | 0 bytes/s, done.
31 Total 3 (delta 0), reused 0 (delta 0)
32 To 192.1.1.103:/apps/git-repo/remote.git
33  * [new branch]      master -> master

1.3、Http协议(DumpSmart)

Git的http协议通讯是依靠WEB容器来实现的，而在Git1.6.6版本以前就只提供哑协议，可以理解为是只读的，

不能做代码的推送。而在哑协议中，它会基于web容器将版本库的内容当作静态文件访问读取的，

所以搭建起来比较简单,在这里使用nginx。还有在这里演示哑协议

首先在linux服务器上

## 初始化一个空仓库
git init --bare remote.git
## 开启post-upadte钩子
cd remote.git/hooks
mv post-update.sample post-update
./post-update

然后配置nginx.conf,并启动nginx

http {
    include       mime.types;
    default_type  application/octet-stream;

    log_format  main  ‘$remote_addr - $remote_user [$time_local] "$request" ‘
                      ‘$status $body_bytes_sent "$http_referer" ‘
                      ‘"$http_user_agent" "$http_x_forwarded_for"‘;

    access_log  logs/access.log  main;

    sendfile        on;

    keepalive_timeout  65;



    server {
        listen       80;
        server_name  localhost;


        location / {
            root   /apps/git-repo;
        }


        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }

    }


}

然后在本地尝试克隆到创建文本到最后的推送，clone的地址 git clone http://192.1.1.103/remote.git remote 

可以看到能够拉取代码，但是不能推送代码。

hjjie@mrforever MINGW64 /e/git_study3
$ git clone http://192.1.1.103/remote.git remote
Cloning into ‘remote‘...
warning: You appear to have cloned an empty repository.

hjjie@mrforever MINGW64 /e/git_study3
$ cd remote/

hjjie@mrforever MINGW64 /e/git_study3/remote (master)
$ echo ‘hello git‘ > git.txt; git add -A; git commit -am ‘first commit‘; git pus                                                                                                                                  h;
warning: LF will be replaced by CRLF in git.txt.
The file will have its original line endings in your working directory.
warning: LF will be replaced by CRLF in git.txt.
The file will have its original line endings in your working directory.
[master (root-commit) fcebf87] first commit
 1 file changed, 1 insertion(+)
 create mode 100644 git.txt
error: Cannot access URL http://192.1.1.103/remote.git/, return code 22
fatal: git-http-push failed
error: failed to push some refs to ‘http://192.1.1.103/remote.git‘

另外查看nginx的access.log文件可以看出更多的访问细节，是通过一系列的引用Refs，最后指引到需要的静态文件

1.4、Git协议

Git协议是Git 里的一个特殊的守护进程然后会监听在一个特定的端口（9418），类似于 SSH 服务。

要让版本库支持 Git 协议，需要先创建一个 git-daemon-export-ok 文件.是 Git 协议守护进程为这个版本库提供服务的必要条件。

另外它的访问速度很快的，但缺乏授权机制，还有一般企业公司不会开放9418这个非标准的端口。

在Linux服务器上：

cd apps/git-repo/remote.git
## 创建一个空文件
touch git-daemon-export-ok
## 以守护进程方式启动git服务
$nohub git daemon --reuseaddr --base-path=/apps/git-repo/ /apps/git-repo/ &

然后在本地尝试克隆 git clone git://192.1.1.103:9418/remote.git 

hjjie@mrforever MINGW64 /e/git_study4
$ git clone git://192.1.1.103:9418/remote.git
Cloning into ‘remote‘...
warning: You appear to have cloned an empty repository.

 

本文作者：hjjay
原文出处：https://www.cnblogs.com/jayhou/p/12264183.html
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