Mention Makefile.dist in README

Author: csstaub

CROSS-COMPILE.md

@@ -19,6 +19,9 @@ For example, to build a static 64-bit Windows binary:
       -ldflags '-w -extldflags "-static" -extld x86_64-w64-mingw32-gcc' \
       github.com/square/ghostunnel
 
-For more info, see [xgo][xgo]'s README on GitHub.
+Ghostunnel ships with a `Makefile.dist` that will cross-compile for
+darwin/amd64, linux/amd64, windows/386 and windows/amd64 when asked to build
+the `dist` target. Note that [xgo][xgo] (and Docker) must already be installed
+to run this. For more info, see also [xgo][xgo]'s README on GitHub.
 
 [xgo]: https://github.com/karalabe/xgo

Makefile

@@ -1,5 +1,10 @@
 SOURCE_FILES := $(shell find . \( -name '*.go' -not -path './vendor*' \))
 INTEGRATION_TESTS := $(shell find tests -name 'test-*.py' -exec basename {} .py \;)
+VERSION := $(shell git describe --always --dirty)
+
+# Ghostunnel binary
+ghostunnel: $(SOURCE_FILES)
+	go build -ldflags '-X main.version=${VERSION}' -o ghostunnel .
 
 # Test binary with coverage instrumentation
 ghostunnel.test: $(SOURCE_FILES)

README.md

@@ -65,10 +65,21 @@ on how to generate new ones with OpenSSL).
 
 Ghostunnel is available through [GitHub releases][rel] and through [Docker Hub][hub].
 
-Note that ghostunnel requires Go 1.9 or later to build, and CGO is required for PKCS#11 support.
+Binaries can be built from source as follows (cross-compile requires Docker and [xgo][xgo]):
+
+    # Compile for local architecture
+    make ghostunnel
+
+    # Cross-compile release binaries
+    make -f Makefile.dist dist
+
+Note that ghostunnel requires Go 1.9 or later to build, and CGO is required for
+PKCS#11 support.  See also [CROSS-COMPILE.md](CROSS-COMPILE.md) for
+instructions on how to cross-compile a custom build with CGO enabled.
 
 [rel]: https://github.com/square/ghostunnel/releases
 [hub]: https://hub.docker.com/r/squareup/ghostunnel
+[xgo]: https://github.com/karalabe/xgo
 
 ### Develop