reproxy/lib/plugin.go
Umputun 7139c57766
RPC plugins support (#85)
* wip

* resolve merge artifacts

* full coverage for conductor

* wire plugin conductor to main and proxy

* wip, with separate match handler

* split matching logic with another handler, add initial docs

* move parts of proxy to handlers, add tests

* add headers in to be sent to proxied url

* merged from master

* add example with docker compose

* supress excesive debug reporting 0-9 disabled in docker

* add plugin tests

* randomize test port

* lint: minor warns

* lint: err shadow
2021-06-01 02:56:39 -05:00

113 lines
2.7 KiB
Go

package lib
import (
"bytes"
"context"
"encoding/json"
"fmt"
"net"
"net/http"
"net/rpc"
"time"
log "github.com/go-pkgz/lgr"
"github.com/go-pkgz/repeater"
)
// Plugin provides cancelable rpc server used to run custom plugins
type Plugin struct {
Name string `json:"name"`
Address string `json:"address"`
Methods []string `json:"methods"`
}
// Do register the plugin, send info to reproxy conductor and activate RPC listener.
// On completion unregister from reproxy. Blocking call, should run in goroutine on the caller side
// rvcr is provided struct implemented at least one RPC methods with the signature like this:
// func(req lib.Request, res *lib.Response) (err error)
// see [examples/plugin]() for more info
func (p *Plugin) Do(ctx context.Context, conductor string, rcvr interface{}) (err error) {
ctxCancel, cancel := context.WithCancel(ctx)
defer cancel()
if err = rpc.RegisterName(p.Name, rcvr); err != nil {
return fmt.Errorf("can't register plugin %s: %v", p.Name, err)
}
log.Printf("[INFO] register rpc %s:%s", p.Name, p.Address)
client := http.Client{Timeout: time.Second}
time.AfterFunc(time.Millisecond*50, func() {
// registration http call delayed to let listener time to start
err = repeater.NewDefault(10, time.Millisecond*500).Do(ctx, func() error {
return p.send(&client, conductor, "POST")
})
if err != nil {
log.Printf("[ERROR] can't register with reproxy for %s: %v", p.Name, err)
cancel()
}
})
defer func() {
if e := p.send(&client, conductor, "DELETE"); e != nil {
log.Printf("[WARN] can't unregister with reproxy for %s: %v", p.Name, err)
}
}()
return p.listen(ctxCancel)
}
func (p *Plugin) listen(ctx context.Context) error {
listener, err := net.Listen("tcp", p.Address)
if err != nil {
return fmt.Errorf("can't listen on %s: %v", p.Address, err)
}
go func() {
<-ctx.Done()
if err := listener.Close(); err != nil {
log.Printf("[WARN] can't lose plugin listener")
}
}()
for {
log.Printf("[DEBUG] plugin listener for %s:%s activated", p.Name, p.Address)
conn, err := listener.Accept()
if err != nil {
select {
case <-ctx.Done():
return ctx.Err()
default:
return fmt.Errorf("accept failed for %s: %v", p.Name, err)
}
}
go rpc.ServeConn(conn)
}
}
func (p *Plugin) send(client *http.Client, conductor, method string) error {
if conductor == "" {
return nil
}
data, err := json.Marshal(p)
if err != nil {
return err
}
req, err := http.NewRequest(method, conductor, bytes.NewReader(data))
if err != nil {
return err
}
resp, err := client.Do(req)
if err != nil {
return err
}
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("invalid status %s", resp.Status)
}
return nil
}