nexus
为 golang 项目添加 nexus 的代理
nexus 仓库类型
默认情况下 nexus 只支持 golang 的 proxy 和 group 类型的仓库，没有 hosted 类型的仓库：
从下面的官方文档
得知：
You can serve and cache modules remotely from resources such as GitHub. Currently, hosted repositories aren’t available.
您可以从 GitHub 等资源远程提供和缓存模块。目前，hosted 存储库不可用。
配置 go proxy 仓库
创建新的 go proxy 仓库：
注意：取消勾选 Cache responses for content not present in the proxied repository 选项。
创建两个 go proxy 仓库：
- go-proxy-official-io: https://goproxy.io/
- go-proxy-cn: https://goproxy.cn
其他备选（暂时不用）：
- go-proxy-official: https://proxy.golang.org
- go-proxy-aliyun: https://mirrors.aliyun.com/goproxy/
- go-proxy-tencent: https://mirrors.cloud.tencent.com/go/
- go-proxy-ustc: https://goproxy.cn
再新建一个名为 go-public 的 group 类型的仓库，将上述 proxy 仓库添加进去，顺序为：
- go-proxy-cn
- go-proxy-official-io
记录此时仓库的地址备用，如：
http://192.168.3.91:8081/repository/go-public/
验证
备注： 在设置好 goproxy 之后再验证
mkdir -p ~/work/code/temp/go-demo
cd ~/work/code/temp/go-demo
git clone https://github.com/gobuffalo/buffalo
cd buffalo
go build
以下为输出:
go: downloading github.com/dustin/go-humanize v1.0.1
go: downloading github.com/gobuffalo/envy v1.10.2
go: downloading github.com/gobuffalo/events v1.4.3
go: downloading github.com/gobuffalo/flect v1.0.0
go: downloading github.com/gobuffalo/grift v1.5.2
go: downloading github.com/gobuffalo/logger v1.0.7
go: downloading github.com/gobuffalo/plush/v4 v4.1.18
go: downloading github.com/gobuffalo/refresh v1.13.3
go: downloading github.com/gorilla/handlers v1.5.1
go: downloading github.com/gorilla/mux v1.8.0
go: downloading github.com/gorilla/sessions v1.2.1
go: downloading github.com/gobuffalo/nulls v0.4.2
go: downloading github.com/monoculum/formam v3.5.5+incompatible
go: downloading github.com/sirupsen/logrus v1.9.0
go: downloading github.com/gobuffalo/meta v0.3.3
go: downloading github.com/spf13/cobra v1.6.1
go: downloading github.com/gobuffalo/github_flavored_markdown v1.1.3
go: downloading github.com/gobuffalo/helpers v0.6.7
go: downloading github.com/gobuffalo/tags/v3 v3.1.4
go: downloading golang.org/x/text v0.6.0
go: downloading github.com/joho/godotenv v1.4.0
go: downloading github.com/rogpeppe/go-internal v1.9.0
go: downloading github.com/felixge/httpsnoop v1.0.1
go: downloading golang.org/x/term v0.0.0-20220722155259-a9ba230a4035
go: downloading github.com/gorilla/securecookie v1.1.1
go: downloading github.com/BurntSushi/toml v1.2.1
go: downloading github.com/gofrs/uuid v4.2.0+incompatible
go: downloading golang.org/x/sys v0.0.0-20220908164124-27713097b956
go: downloading github.com/spf13/pflag v1.0.5
go: downloading github.com/microcosm-cc/bluemonday v1.0.20
go: downloading github.com/sourcegraph/annotate v0.0.0-20160123013949-f4cad6c6324d
go: downloading github.com/sourcegraph/syntaxhighlight v0.0.0-20170531221838-bd320f5d308e
go: downloading golang.org/x/net v0.0.0-20221002022538-bcab6841153b
go: downloading github.com/fatih/color v1.13.0
go: downloading github.com/fsnotify/fsnotify v1.6.0
go: downloading github.com/mitchellh/go-homedir v1.1.0
go: downloading gopkg.in/yaml.v3 v3.0.1
go: downloading github.com/fatih/structs v1.1.0
go: downloading github.com/gobuffalo/validate/v3 v3.3.3
go: downloading github.com/sergi/go-diff v1.2.0
go: downloading github.com/mattn/go-colorable v0.1.9
go: downloading github.com/mattn/go-isatty v0.0.14
go: downloading github.com/aymerick/douceur v0.2.0
go: downloading github.com/gorilla/css v1.0.0
此时本地 gopath 目录下能看到这些已经下载的 go module：
$ ls /home/sky/work/soft/gopath/pkg/mod/github.com
aymerick felixge gorilla mitchellh sirupsen
'!burnt!sushi' fsnotify joho monoculum sourcegraph
dustin gobuffalo mattn rogpeppe spf13
fatih gofrs microcosm-cc sergi
打开 nexus，浏览 go-public 仓库地址，能看到这些 go module 已经被缓存：
打开顺序排在第一位的 go-proxy-cn 仓库，也能看到这些 go module 已经被缓存：
而排在顺序第二的代理仓库，则为空：
这说明 go group 类型的仓库，会按照添加的顺序，依次查找缓存的 go module，如果找到，则使用，否则继续查找下一个，直到找到或者查找完所有仓库。