Include generated Protocol Buffer descriptor.

The Protocol Buffer compiler supports generating a machine-readable
descriptor file encoded as a provided Protocol Buffer message type,
which can be used to decode messages that have been encoded with it
after-the-fact.  The generated descriptor also bundles in dependent
message types.

We can use this to perform forensics on old Prometheus clients, if
necessary.

Makefile

@@ -76,7 +76,7 @@ test: build
 	go test ./utility/... $(GO_TEST_FLAGS)
 	go test ./web/... $(GO_TEST_FLAGS)
 
-web: preparation
+web: preparation model
 	$(MAKE) -C web
 
 .PHONY: advice binary build clean documentation format model package preparation run search_index source_path test

model/Makefile

@@ -11,14 +11,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+all: generated
+
+SUFFIXES:
+
 MAKE_ARTIFACTS = generated-stamp
 
-all: generated
+include ../Makefile.INCLUDE
 
 generated: generated-stamp
 
 generated-stamp: data.proto
-	protoc --go_out=generated/ data.proto
+	protoc  --proto_path=$(PREFIX)/include:. --go_out=generated/ --descriptor_set_out=generated/descriptor.blob data.proto
 	touch $@
 
 clean:

model/data.proto

@@ -11,7 +11,9 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package dto;
+package io.prometheus;
+
+import "google/protobuf/descriptor.proto";
 
 message LabelPair {
   optional string name = 1;

model/generated/.gitignore

@@ -1,4 +1,2 @@
-*.cc
-*.go
-*.h
-*.o
+data.pb.go
+descriptor.blob

web/blob/Makefile

@@ -13,10 +13,19 @@
 
 all: files.go
 
-files.go: $(shell find ../templates/ ../static/ -type f)
-	../../utility/embed-static.sh ../static ../templates | gofmt > $@
+SUFFIXES:
+
+generated:
+	mkdir -vp generated
+
+generated/protocol_buffer.descriptor: generated ../../model/generated/descriptor.blob
+	cp ../../model/generated/descriptor.blob -f $@
+
+files.go: $(shell find ../templates/ ../static/ -type f) generated/protocol_buffer.descriptor
+	../../utility/embed-static.sh ../static ../templates ./generated | gofmt > $@
 
 clean:
 	-rm  files.go
+	-rm -rf generated
 
 .PHONY: clean