Add website preview via Netlify

.gitignore

@@ -60,3 +60,6 @@ client/build-external/*
 prog/staticui/*
 prog/externalui/*
 client/build-pkg
+
+# Website
+site-build

.ruby-version

@@ -0,0 +1 @@
+2.3.0

Makefile

@@ -224,3 +224,14 @@ deps:
 		github.com/mattn/goveralls \
 		github.com/weaveworks/github-release \
 		github.com/2opremio/trifles/wscat
+
+# This target is only intended for use in Netlify CI environment for generating preview pages on feature branches and pull requests.
+# We need to obtain website repository (checked out under `site-build`) and place `site` directory into the context (`site-build/_weave_net_docs`).
+# We then run make in `site-build` and Netlify will publish the output (`site-build/_site`).
+netlify-site-preview:
+	@mkdir -p site-build
+	@curl --user $(WEBSITE_GITHUB_USER) --silent 'https://codeload.github.com/weaveworks/website-next/tar.gz/$(WEBSITE_BRANCH)' \
+	  | tar --extract --gunzip --directory site-build --strip 1
+	@cp -r site site-build/_weave_scope_docs
+	@$(MAKE) -C site-build netlify_ensure_install
+	@$(MAKE) -C site-build BUILD_ENV=netlify