Prevent site indexing for preview builds

README.md

@@ -297,6 +297,27 @@ run if the API site is running slow.
 
 For a list of languages, look in the `_translations` directory.
 
+#### Publishing Previews
+
+You can publish your previews online to any static hosting service.
+[GitHub pages](https://pages.github.com/) is a free service available to
+all GitHub users that works with Bitcoin.org's site hierarchy.
+
+Before building a preview site, it is recommended that you set the
+environmental variable `BITCOINORG_BUILD_TYPE` to "preview".  This will
+enable some content that would otherwise be hidden and also create a
+robots.txt file that will help prevent the site from being indexed by
+search engines and mistaken for the actual Bitcoin.org website.
+
+In the bash shell, you can do this by running the following command line
+before building you preview:
+
+    export BITCOINORG_BUILD_TYPE=preview
+
+You can also add this line to your `~/.bashrc` file if you frequently
+build site previews so that you don't have to remember to run it for
+each shell.
+
 ## Developer Documentation
 
 Most parts of the documentation can be found in the [_includes](https://github.com/bitcoin-dot-org/bitcoin.org/tree/master/_includes)

_build/update_txpreview.sh

@@ -11,6 +11,9 @@ WORKDIR=`mktemp -d`
 LIVEDIR=`mktemp -d`
 SITEDIR='/bitcoin.org/txpreview'
 DESTDIR='/var/www/txpreview'
+BITCOINORG_BUILD_TYPE='preview'
+
+export BITCOINORG_BUILD_TYPE
 
 # Stop script in case a single command fails
 set -e

robots.txt

@@ -1 +1,12 @@
+---
+# This file is licensed under the MIT License (MIT) available on
+# http://opensource.org/licenses/MIT.
+
+layout: null
+---
+{% if site.env.BITCOINORG_BUILD_TYPE == 'preview' %}
+User-agent: *
+Disallow: /
+{% else %}
 Sitemap: https://bitcoin.org/sitemap.xml
+{% endif %}