import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

taskcluster/docs/docker-images.rst

@@ -0,0 +1,42 @@
+.. taskcluster_dockerimages:
+
+=============
+Docker Images
+=============
+
+TaskCluster Docker images are defined in the source directory under
+``testing/docker``. Each directory therein contains the name of an
+image used as part of the task graph.
+
+Adding Extra Files to Images
+============================
+
+Dockerfile syntax has been extended to allow *any* file from the
+source checkout to be added to the image build *context*. (Traditionally
+you can only ``ADD`` files from the same directory as the Dockerfile.)
+
+Simply add the following syntax as a comment in a Dockerfile::
+
+   # %include <path>
+
+e.g.
+
+   # %include mach
+   # %include testing/mozharness
+
+The argument to ``# %include`` is a relative path from the root level of
+the source directory. It can be a file or a directory. If a file, only that
+file will be added. If a directory, every file under that directory will be
+added (even files that are untracked or ignored by version control).
+
+Files added using ``# %include`` syntax are available inside the build
+context under the ``topsrcdir/`` path.
+
+Files are added as they exist on disk. e.g. executable flags should be
+preserved. However, the file owner/group is changed to ``root`` and the
+``mtime`` of the file is normalized.
+
+Here is an example Dockerfile snippet::
+
+   # %include mach
+   ADD topsrcdir/mach /home/worker/mach