Manager: use different HTTP headers to do conditional fetch of depsgraph

packages/flamenco-manager-go/src/flamenco-manager/flamenco/http.go

@@ -8,14 +8,12 @@ import (
 	"io/ioutil"
 	"net/http"
 	"net/url"
-	"time"
 
 	log "github.com/Sirupsen/logrus"
 )
 
 // For timestamp parsing
 const IsoFormat = "2006-01-02T15:04:05-0700"
-const LastModifiedHeaderFormat = time.RFC1123
 
 /**
  * Decodes JSON and writes a Bad Request status if it fails.

packages/flamenco-manager-go/src/flamenco-manager/flamenco/http_test.go

-package flamenco
-
-import (
-	"time"
-
-	"github.com/stretchr/testify/assert"
-
-	check "gopkg.in/check.v1"
-)
-
-type HttpTestSuite struct{}
-
-var _ = check.Suite(&HttpTestSuite{})
-
-func (s *HttpTestSuite) TestParseDates(c *check.C) {
-	parsed_iso, err1 := time.Parse(IsoFormat, "2017-01-23T13:04:05+0200")
-	parsed_http, err2 := time.Parse(LastModifiedHeaderFormat, "Mon, 23 Jan 2017 13:04:05 CEST")
-	assert.Nil(c, err1)
-	assert.Nil(c, err2)
-	assert.Equal(c, parsed_iso, parsed_http)
-}

packages/flamenco-manager-go/src/flamenco-manager/flamenco/upstream.go

@@ -159,7 +159,7 @@ func download_tasks_from_upstream(config *Conf, mongo_sess *mgo.Session) {
 	if settings.DepsgraphLastModified != nil {
 		log.Infof("Getting tasks from upstream Flamenco %s If-Modified-Since %s", get_url,
 			*settings.DepsgraphLastModified)
-		req.Header.Set("If-Modified-Since", *settings.DepsgraphLastModified)
+		req.Header.Set("X-Flamenco-If-Updated-Since", *settings.DepsgraphLastModified)
 	} else {
 		log.Infof("Getting tasks from upstream Flamenco %s", get_url)
 	}
@@ -174,7 +174,7 @@ func download_tasks_from_upstream(config *Conf, mongo_sess *mgo.Session) {
 		log.Debug("Server-side depsgraph was not modified, nothing to do.")
 		return
 	}
-	if resp.StatusCode == 204 {
+	if resp.StatusCode == http.StatusNoContent {
 		log.Info("No tasks for us; sleeping.")
 		return
 	}
@@ -223,7 +223,7 @@ func download_tasks_from_upstream(config *Conf, mongo_sess *mgo.Session) {
 	}
 
 	// Check if we had a Last-Modified header, since we need to remember that.
-	last_modified := resp.Header.Get("Last-Modified")
+	last_modified := resp.Header.Get("X-Flamenco-Last-Updated")
 	if last_modified != "" {
 		log.Info("Last modified task was at ", last_modified)
 		settings.DepsgraphLastModified = &last_modified