如何只克隆部分代码?
一、需求
根据整体规划需求,多个模块的源码共存在一个仓库中。在一些场景执行中,需要考虑执行效率,仅关注部分路径的代码。即仅需获取部分路径的文件。
二、解决方案
利用Sparse Checkout模式。官方信息描述如下:
Sparse checkout
"Sparse checkout" allows to sparsely populate working directory. It uses skip-worktree bit (see git-update-index(1)) to tell Git whether a file on working directory is worth looking at.
"git read-tree" and other merge-based commands ("git merge", "git checkout"…) can help maintaining skip-worktree bitmap and working directory update. $GIT_DIR/info/sparse-checkout is used to define the skip-worktree reference bitmap. When "git read-tree" needs to update working directory, it will reset skip-worktree bit in index based on this file, which uses the same syntax as .gitignore files. If an entry matches a pattern in this file, skip-worktree will be set on that entry. Otherwise, skip-worktree will be unset.
Then it compares the new skip-worktree value with the previous one. If skip-worktree turns from unset to set, it will add the corresponding file back. If it turns from set to unset, that file will be removed.
While $GIT_DIR/info/sparse-checkout is usually used to specify what files are in. You can also specify what files are not in, using negate patterns.
三、基本操作过程
1. 准备
$mkdir code_dir
$cd code_dir
$git init
$git remote add -f origin <url>
2. 启用sparsecheckout模式
$git config core.sparsecheckout true
3. 设置排除的路径
编辑 .git/info/sparse-checkout
$echo “want_dir/*” >> .git/info/sparse-checkout
4. 拉取代码
$git pull origin master
四、如何设置sparsecheckout文件
子目录的匹配
- 如果目录名称前带斜杠,如/docs/,将只匹配项目根目录下的docs目录
- 如果目录名称前不带斜杠,如docs/,其他目录下如果也有这个名称的目录,如test/docs/也能被匹配。
- 如果写了多级目录,如docs/05/,则不管前面是否带有斜杠,都只匹配项目根目录下的目录,如test/docs/05/不能被匹配。
通配符 “*“ (星号)
支持通配符 “*“,如可以写成以下格式:
*docs/
index.*
*.gif
排除项 “!” (感叹号)
支持排除项 “!”,如只想排除排除项目下的 “docs” 目录,可以按如下格式写:
/*
!/docs/
五、如何关闭sparsecheckout模式
- 将core.sparsecheckout设为false
- 修改 .git/info/sparse-checkout 文件,用一个”*“号替代其中的内容
- 执行 checkout 或 read-tree 命令
六、注意事项
- 如果排除是临时性的,要及时清除相关设置,否则就是一个隐患,即导致环境不可重入。
- 仅限 Git 1.7以上版本