step0、参考：language servers used with YCM

step1、安装依赖

step2、创建~/.lsp/yaml-language-server目录

mkdir -p ~/.lsp/yaml-language-server

step3、进入~/.lsp/yaml-language-server目录

cd ~/.lsp/yaml-language-server

step4、使用npm安装yaml-language-server

npm install yaml-language-server

step5、在~/.vimrc中加入如下的配置

let g:ycm_language_server = [
    \{  'name': 'yaml',
    \   'filetypes': [ 'yaml' ],
    \   'cmdline': [ 'node', expand( '$HOME/.lsp/yaml-language-server/node_modules/.bin/yaml-language-server' ), '--stdio' ],
    \}
]