Pull request: websvc-config-manager

Merge in DNS/adguard-home from websvc-config-manager to master

Squashed commit of the following:

commit 2143b47c6528030dfe059172888fddf9061e42da
Author: Ainar Garipov <A.Garipov@AdGuard.COM>
Date:   Tue Oct 4 14:50:47 2022 +0300

    next: add config manager

internal/next/websvc/http.go

@@ -0,0 +1,109 @@
+package websvc
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/netip"
+	"time"
+
+	"github.com/AdguardTeam/golibs/log"
+)
+
+// HTTP Settings Handlers
+
+// ReqPatchSettingsHTTP describes the request to the PATCH /api/v1/settings/http
+// HTTP API.
+type ReqPatchSettingsHTTP struct {
+	// TODO(a.garipov): Add more as we go.
+	//
+	// TODO(a.garipov): Add wait time.
+
+	Addresses       []netip.AddrPort `json:"addresses"`
+	SecureAddresses []netip.AddrPort `json:"secure_addresses"`
+	Timeout         JSONDuration     `json:"timeout"`
+}
+
+// HTTPAPIHTTPSettings are the HTTP settings as used by the HTTP API.  See the
+// HttpSettings object in the OpenAPI specification.
+type HTTPAPIHTTPSettings struct {
+	// TODO(a.garipov): Add more as we go.
+
+	Addresses       []netip.AddrPort `json:"addresses"`
+	SecureAddresses []netip.AddrPort `json:"secure_addresses"`
+	Timeout         JSONDuration     `json:"timeout"`
+	ForceHTTPS      bool             `json:"force_https"`
+}
+
+// handlePatchSettingsHTTP is the handler for the PATCH /api/v1/settings/http
+// HTTP API.
+func (svc *Service) handlePatchSettingsHTTP(w http.ResponseWriter, r *http.Request) {
+	req := &ReqPatchSettingsHTTP{}
+
+	// TODO(a.garipov): Validate nulls and proper JSON patch.
+
+	err := json.NewDecoder(r.Body).Decode(&req)
+	if err != nil {
+		writeJSONErrorResponse(w, r, fmt.Errorf("decoding: %w", err))
+
+		return
+	}
+
+	newConf := &Config{
+		ConfigManager:   svc.confMgr,
+		TLS:             svc.tls,
+		Addresses:       req.Addresses,
+		SecureAddresses: req.SecureAddresses,
+		Timeout:         time.Duration(req.Timeout),
+		ForceHTTPS:      svc.forceHTTPS,
+	}
+
+	writeJSONOKResponse(w, r, &HTTPAPIHTTPSettings{
+		Addresses:       newConf.Addresses,
+		SecureAddresses: newConf.SecureAddresses,
+		Timeout:         JSONDuration(newConf.Timeout),
+		ForceHTTPS:      newConf.ForceHTTPS,
+	})
+
+	cancelUpd := func() {}
+	updCtx := context.Background()
+
+	ctx := r.Context()
+	if deadline, ok := ctx.Deadline(); ok {
+		updCtx, cancelUpd = context.WithDeadline(updCtx, deadline)
+	}
+
+	// Launch the new HTTP service in a separate goroutine to let this handler
+	// finish and thus, this server to shutdown.
+	go func() {
+		defer cancelUpd()
+
+		updErr := svc.confMgr.UpdateWeb(updCtx, newConf)
+		if updErr != nil {
+			writeJSONErrorResponse(w, r, fmt.Errorf("updating: %w", updErr))
+
+			return
+		}
+
+		// TODO(a.garipov): Consider better ways to do this.
+		const maxUpdDur = 10 * time.Second
+		updStart := time.Now()
+		var newSvc ServiceWithConfig[*Config]
+		for newSvc = svc.confMgr.Web(); newSvc == svc; {
+			if time.Since(updStart) >= maxUpdDur {
+				log.Error("websvc: failed to update svc after %s", maxUpdDur)
+
+				return
+			}
+
+			log.Debug("websvc: waiting for new websvc to be configured")
+			time.Sleep(1 * time.Second)
+		}
+
+		updErr = newSvc.Start()
+		if updErr != nil {
+			log.Error("websvc: new svc failed to start with error: %s", updErr)
+		}
+	}()
+}