Milo: Add LogDog annotation stream support.

appengine/cmd/milo/logdog/http.go

Index: appengine/cmd/milo/logdog/http.go
diff --git a/appengine/cmd/milo/logdog/http.go b/appengine/cmd/milo/logdog/http.go
new file mode 100644
index 0000000000000000000000000000000000000000..0c53c16336c80a0b22c0afb5053ca2c6b273c122
--- /dev/null
+++ b/appengine/cmd/milo/logdog/http.go
@@ -0,0 +1,73 @@
+// Copyright 2016 The LUCI Authors. All rights reserved.
+// Use of this source code is governed under the Apache License, Version 2.0
+// that can be found in the LICENSE file.
+
+package logdog
+
+import (
+	"net/http"
+	"strings"
+
+	"github.com/julienschmidt/httprouter"
+	"github.com/luci/luci-go/appengine/cmd/milo/miloerror"
+	"github.com/luci/luci-go/appengine/cmd/milo/settings"
+	authClient "github.com/luci/luci-go/appengine/gaeauth/client"
+	"github.com/luci/luci-go/common/config"
+	log "github.com/luci/luci-go/common/logging"
+	"github.com/luci/luci-go/logdog/common/types"
+	"github.com/luci/luci-go/server/templates"
+
+	"golang.org/x/net/context"
+)
+
+// AnnotationStream is a ThemedHandler that renders a LogDog Milo annotation
+// protobuf stream.
+//
+// The protobuf stream is fetched live from LogDog and cached locally, either
+// temporarily (if incomplete) or indefinitely (if complete).
+type AnnotationStream struct {
+	// logDogClient is a reusable HTTP client to use for LogDog.
+	logDogClient *http.Client
+}
+
+// GetTemplateName implements settings.ThemedHandler.
+func (s *AnnotationStream) GetTemplateName(t settings.Theme) string {
+	return "build.html"
+}
+
+// Render implements settings.ThemedHandler.
+func (s *AnnotationStream) Render(c context.Context, req *http.Request, p httprouter.Params) (*templates.Args, error) {
+	// Initialize the LogDog client authentication.
+	a, err := authClient.Transport(c, nil, nil)
+	if err != nil {
+		log.WithError(err).Errorf(c, "Failed to get transport for LogDog server.")
+		return nil, &miloerror.Error{
+			Code: http.StatusInternalServerError,
+		}
+	}
+
+	as := annotationStreamRequest{
+		AnnotationStream: s,
+
+		project: config.ProjectName(p.ByName("project")),
+		path:    types.StreamPath(strings.Trim(p.ByName("path"), "/")),
+		host:    req.FormValue("host"),
+
+		logDogClient: http.Client{
+			Transport: a,
+		},
+	}
+	if err := as.normalize(); err != nil {
+		return nil, err
+	}
+
+	// Load the Milo annotation protobuf from the annotation stream.
+	if err := as.load(c); err != nil {
+		return nil, err
+	}
+
+	// Convert the Milo Annotation protobuf to Milo objects.
+	return &templates.Args{
+		"Build": as.toMiloBuild(c),
+	}, nil
+}