运行时插件

插件是将外部代码集成到 micro 工具包中的一种方式. 这与 go-micro 插件完全分离. 使用插件可以在此处添加其他标志, 命令和 HTTP 处理程序到工具包.

工作原理

在 micro/plugin 下有一个全局插件管理器, 它由将在整个工具包中使用的插件组成. 插件可以通过调用进行注册. 每个组件 (api, web, proxy, cli, bot) 都有一个单独的插件管理器, 用于注册插件, 该插件应仅作为该组件的一部分添加. 它们可以通过调用 plugin.Register, api.Register, web.Register 等方式使用.

下面是接口

// Plugin is the interface for plugins to micro. It differs from go-micro in that it's for
// the micro API, Web, Proxy, CLI. It's a method of building middleware for the HTTP side.
type Plugin interface {
    // Global Flags
    Flags() []cli.Flag
    // Sub-commands
    Commands() []cli.Command
    // Handle is the middleware handler for HTTP requests. We pass in
    // the existing handler so it can be wrapped to create a call chain.
    Handler() Handler
    // Init called when command line args are parsed.
    // The initialised cli.Context is passed in.
    Init(*cli.Context) error
    // Name of the plugin
    String() string
}

// Manager is the plugin manager which stores plugins and allows them to be retrieved.
// This is used by all the components of micro.
type Manager interface {
        Plugins() map[string]Plugin
        Register(name string, plugin Plugin) error
}

// Handler is the plugin middleware handler which wraps an existing http.Handler passed in.
// Its the responsibility of the Handler to call the next http.Handler in the chain.
type Handler func(http.Handler) http.Handler

如何使用

下面是一个简单的插件示例, 该插件添加一个标志, 然后打印值

插件

在顶层目录中创建 plugins.go 文件

package main

import (
    "log"
    "github.com/micro/cli"
    "github.com/micro/micro/plugin"
)

func init() {
    plugin.Register(plugin.NewPlugin(
        plugin.WithName("example"),
        plugin.WithFlag(cli.StringFlag{
            Name:   "example_flag",
            Usage:  "This is an example plugin flag",
            EnvVar: "EXAMPLE_FLAG",
            Value: "avalue",
        }),
        plugin.WithInit(func(ctx *cli.Context) error {
            log.Println("Got value for example_flag", ctx.String("example_flag"))
            return nil
        }),
    ))
}

构建代码

只需使用插件构建 micro

go build -o micro ./main.go ./plugin.go

仓库

工具包的插件可以在此仓库 github.com/micro/go-plugins/micro 中找到.