Updating with examples of env behavior.

Signed-off-by: Jesse Brown <jabrown85@gmail.com>
buildpacks · Jun 3, 2020 · 564e539 · 564e539
1 parent 9dfb312
commit 564e539
Showing 1 changed file with 16 additions and 2 deletions.
diff --git a/text/0000-process-specific-env.md b/text/0000-process-specific-env.md
@@ -39,7 +39,21 @@ Each env or profile layer dir can have subdirs like `<layer>/env.launch/web/` an
 # How it Works
 [how-it-works]: #how-it-works
 
-Lifecycle would use the identifier of the intended launch process to bring in additional `env` and `profile.d` files. The launcher would process these process specific values _after_ less specific values to allow [Environment Variable Modification Rules](https://github.com/buildpacks/spec/blob/master/buildpack.md#environment-variable-modification-rules) to apply in the context of a single buildpack.
+Lifecycle would use the identifier of the intended launch process to bring in additional `env` and `profile.d` files. The launcher would sort these process specific values _after_ less specific values to allow [Environment Variable Modification Rules](https://github.com/buildpacks/spec/blob/master/buildpack.md#environment-variable-modification-rules) to apply as expected.
+
+The environment modification rules should be updated to reflect that sort order for `.prepend`, `.append`, and `.override` to reflect that process specific values are more processed in the most overriding order. The following shows an example of processing order for a given layer.
+
+```
+<layers>/<layer>/env/NODE_OPTIONS.append
+<layers>/<layer>/env.launch/NODE_OPTIONS.append
+<layers>/<layer>/env.launch/web/NODE_OPTIONS.append
+```
+
+Example spec update:
+
+- Environment variable file contents originating in the same layer MUST be sorted such that file contents in <layers>/<layer>/env.launch/<process>/ precede file contents in <layers>/<layer>/env.launch/, which must precede <layers>/<layer>/env/.
+- Environment variable file contents originating in the same layer MUST be sorted such that file contents in <layers>/<layer>/env/ precede file contents in <layers>/<layer>/env.build/ or <layers>/<layer>/env.launch/ which must preced file contents in <layers>/<layer>/env.launch/<process>/.
+
 
 # Drawbacks
 [drawbacks]: #drawbacks
@@ -64,4 +78,4 @@ Lifecycle would use the identifier of the intended launch process to bring in ad
 - Should lifecycle ignore invalid entries like `<layers>/<layer>/env.build/web/NODE_OPTIONS`?
 
 # Spec. Changes (OPTIONAL)
-[spec-changes]: #spec-changes
+[spec-changes]: #spec-changes