README
¶
Plugins
Plugins are a way of extending the functionality of Micro
Overview
Plugins enable Micro to be extending and intercepted to provide additional functionality and features. This may include logging, metrics, tracing, authentication, etc. The Plugin model requires registering a struct that matches a plugin interface. It's then registered and setup when Micro starts.
Design
Here's the interface design
// Plugin is the interface for plugins to micro. It differs from go-micro in that it's for
// the micro API, Web, Sidecar, 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
How to use it
Here's a simple example of a plugin that adds a flag and then prints the value
The plugin
Create a plugin.go file in the top level dir
package main
import (
"log"
"github.com/urfave/cli/v2"
"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",
EnvVars: []string{"EXAMPLE_FLAG"},
Value: "avalue",
}),
plugin.WithInit(func(ctx *cli.Context) error {
log.Println("Got value for example_flag", ctx.String("example_flag"))
return nil
}),
))
}
Building the code
Simply build micro with the plugin
go build -o micro ./main.go ./plugin.go
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func IsRegistered ¶
func IsRegistered(plugin Plugin, opts ...PluginOption) bool
IsRegistered check plugin whether registered global. Notice plugin is not check whether is nil
func Register ¶
func Register(plugin Plugin, opts ...PluginOption) error
Register registers a global plugins
Types ¶
type Handler ¶
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 Manager ¶
type Manager interface {
Plugins(...PluginOption) []Plugin
Register(Plugin, ...PluginOption) error
}
Manager is the plugin manager which stores plugins and allows them to be retrieved. This is used by all the components of micro.
type Option ¶
type Option func(o *Options)
func WithCommand ¶
func WithCommand(cmd ...*cli.Command) Option
WithCommand adds commands to a plugin
type Options ¶
type Options struct {
Name string
Flags []cli.Flag
Commands []*cli.Command
Handlers []Handler
Init func(*cli.Context) error
}
Options are used as part of a new plugin
type Plugin ¶
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
}
Plugin is the interface for plugins to micro. It differs from go-micro in that it's for the micro API, Web, Sidecar, CLI. It's a method of building middleware for the HTTP side.
type PluginOption ¶
type PluginOption func(o *PluginOptions)
func Module ¶
func Module(m string) PluginOption
Module will scope the plugin to a specific module, e.g. the "api"
type PluginOptions ¶
type PluginOptions struct {
Module string
}
Source Files