software/helloworld: Use buildout.hash.cfg

software/helloworld/buildout.hash.cfg

+# THIS IS NOT A BUILDOUT FILE, despite purposedly using a compatible syntax.
+# The only allowed lines here are (regexes):
+# - "^#" comments, copied verbatim
+# - "^[" section beginings, copied verbatim
+# - lines containing an "=" sign which must fit in the following categorie.
+#   - "^\s*filename\s*=\s*path\s*$" where "path" is relative to this file
+#     Copied verbatim.
+#   - "^\s*hashtype\s*=.*" where "hashtype" is one of the values supported
+#     by the re-generation script.
+#     Re-generated.
+# - other lines are copied verbatim
+# Substitution (${...:...}), extension ([buildout] extends = ...) and
+# section inheritance (< = ...) are NOT supported (but you should really
+# not need these here).
+[instance-profile]
+filename = instance.cfg.in
+md5sum = 6567f8dedb5cdd93542dc29e96edb547

software/helloworld/software.cfg

 [buildout]
 
 extends =
+# buildout.hash.cfg is used for automated hash calculation of managed
+# instance files by calling update-hash
+  buildout.hash.cfg
 # "slapos" stack describes basic things needed for 99.9% of SlapOS Software
 # Releases
   ../../stack/slapos.cfg
@@ -25,19 +28,26 @@ parts =
   helloweb-go
 
 
+# Macro for jinja templates. The filename is set in buildout.hash.cfg
+# in the section using this template
+[jinja-template]
+recipe = slapos.recipe.template:jinja2
+template = ${:_profile_base_location_}/${:filename}
+mode = 0644
+
 # Download instance.cfg.in (buildout profile used to deployment of instance),
 # replace all ${foo:bar} parameters by real values, and change $${foo:bar} to
 # ${foo:bar}
+# The recipe, template and mode are fetched from jijna-template
 [instance-profile]
-recipe = slapos.recipe.template:jinja2
-template = ${:_profile_base_location_}/instance.cfg.in
+# The <= is buildout verb to use defined template
+<= jinja-template
 rendered = ${buildout:directory}/instance.cfg
-# MD5 checksum can be skipped for development (easier to develop), but must be filled for production
-md5sum = 6567f8dedb5cdd93542dc29e96edb547
-mode = 0644
 extensions = jinja2.ext.do
 context =
   section buildout  buildout
+# md5sum is fetched from buildout.hash.cfg and can be recalculated automatically by
+# calling update-hash
 
 # Pin versions of eggs used that are not already pinned by stack/slapos.cfg
 [versions]