haproxy controller checks the current offloader config before updates.

Most importantly, this tells us the current version number in use
by the dataplane API, which apparently insists that the number is
always counted up (otherwise there are 409 Conflict responses).

pkg/haproxy/dataplane.go

@@ -30,6 +30,7 @@ package haproxy
 
 import (
 	"bytes"
+	"encoding/json"
 	"io"
 	"io/ioutil"
 	"net/http"
@@ -563,3 +564,55 @@ func (client *DataplaneClient) Reloaded(id string) (bool, ReloadState, error) {
 		return false, state, dplaneErr
 	}
 }
+
+type sitesBody struct {
+	version int          `json:"_version,omitempty"`
+	sites   models.Sites `json:"data"`
+}
+
+func (client *DataplaneClient) OffldrStatus() (
+	loaded bool, version int, err error) {
+
+	req, err := client.getReq(sitesPath, http.MethodGet, nil, false)
+	if err != nil {
+		return
+	}
+	resp, err := client.client.Do(req)
+	if err != nil {
+		return
+	}
+	body, err := getBody(resp)
+	if err != nil {
+		return
+	}
+
+	if verStr := resp.Header.Get(versionHdr); verStr != "" {
+		if version, err = strconv.Atoi(verStr); err != nil {
+			return
+		}
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		err = getError(resp, body)
+		return
+	}
+
+	var sb sitesBody
+	if err = json.Unmarshal(body, &sb); err != nil {
+		return
+	}
+	if err = sb.sites.Validate(fmts); err != nil {
+		return
+	}
+	if version == 0 {
+		version = sb.version
+	}
+	// XXX what if version from body & the header don't match?
+	for _, site := range []*models.Site(sb.sites) {
+		if site.Name == frontend {
+			loaded = true
+			break
+		}
+	}
+	return
+}

pkg/haproxy/haproxy.go

@@ -286,6 +286,8 @@ func (hc *Controller) updateInstance(inst *haproxyInst, spec *Spec) error {
 	}
 	hc.log.Infof("Offloader instance %s: TLS config %s accepted for load",
 		inst.name, spec)
+	hc.log.Debugf("Offloader instance %s reload state: %+v", inst.name,
+		state)
 	inst.status.version = tx.Version
 	inst.status.dplaneState = state
 	inst.spec = &Spec{
@@ -364,6 +366,12 @@ func (hc *Controller) updateOffldSvc(svcKey string) error {
 			continue
 		}
 		// XXX metrics
+		hc.log.Debugf("offloader svc %s: get current status", inst.name)
+		if err := hc.getOffldStatus(*inst); err != nil {
+			offldrErr := inst.mkError(err)
+			errs = append(errs, offldrErr)
+			continue
+		}
 		if err := hc.updateInstance(inst, svc.spec); err != nil {
 			offldrErr := inst.mkError(err)
 			errs = append(errs, offldrErr)
@@ -562,6 +570,29 @@ func (hc *Controller) updateOffldrAddrs(key string, addrs []OffldAddr,
 	return errs
 }
 
+func (hc *Controller) getOffldStatus(inst haproxyInst) error {
+	hc.log.Debugf("Offloader instance %s, checking offloader config",
+		inst.name)
+	inst.admMtx.Lock()
+	defer inst.admMtx.Unlock()
+	hc.wg.Add(1)
+	defer hc.wg.Done()
+
+	loaded, version, err := inst.dplane.OffldrStatus()
+	if err != nil {
+		return err
+	}
+	inst.status.version = int64(version)
+	if loaded {
+		hc.log.Infof("Offloader instance %s: offloader configured, "+
+			"version=%d", inst.name, version)
+	} else {
+		hc.log.Infof("Offloader instance %s: offloader not configured,"+
+			" current version=%d", inst.name, version)
+	}
+	return nil
+}
+
 // AddOrUpdateVarnishSvc(key string, addrs []vcl.Address, secrName string,
 //	loadVCL bool) error
 // AddOrUpdateVarnishSvc causes a sync for the Varnish Service