Update tracer readme and makefile.

experimental/tracer/Makefile

@@ -1,11 +1,28 @@
+BUILD_IN_CONTAINER=true
+
 tracer.tar: main/main main/Dockerfile
 	docker build -t weaveworks/tracer main/
 	docker save weaveworks/tracer:latest >$@
 
 main/main: main/*.go main/static.go ptrace/*.go
-	go get -tags netgo ./$(@D)
+
+ifeq ($(BUILD_IN_CONTAINER),true)
+
+main/main:
+	docker run -ti \
+		-v $(shell pwd)/../../:/go/src/github.com/weaveworks/scope \
+		-e GOARCH -e GOOS -e CIRCLECI -e CIRCLE_BUILD_NUM -e CIRCLE_NODE_TOTAL \
+		-e CIRCLE_NODE_INDEX -e COVERDIR -e SLOW \
+		weaveworks/scope-backend-build SCOPE_VERSION=$(SCOPE_VERSION) GO_BUILD_INSTALL_DEPS=$(GO_BUILD_INSTALL_DEPS) -C experimental/tracer $@
+
+else
+
+main/main:
+	#go get -tags netgo ./$(@D)
 	go build -ldflags "-extldflags \"-static\"" -tags netgo -o $@ ./$(@D)
 
+endif
+
 main/static.go: ui/*
 	esc -o main/static.go -prefix ui ui
 

experimental/tracer/README.md

@@ -1,3 +1,7 @@
+Tracer is an prototype app for doing distributed request tracing without applications modifications.
+
+It its very early.  Ask Tom for a demo.
+
 Run tracer:
 - make
 - ./tracer.sh start