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
2025-11-23 22:04:57 +02:00 · 2021-06-01 02:56:39 -05:00
parent 30ca38b1ba
commit 7139c57766
65 changed files with 4053 additions and 227 deletions
--- a/lib/plugin.go
+++ b/lib/plugin.go
@@ -0,0 +1,112 @@
+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
+}