Fix extensions demo now that samples repo has been updated

We don't need to re-create the builder, we just need to update the env vars passed to the buildpack
to make it require things from extensions.

Signed-off-by: Natalie Arellano <[email protected]>

Author: Natalie Arellano

content/docs/extension-guide/create-extension/build-dockerfile.md

@@ -28,32 +28,14 @@ cat $PWD/samples/extensions/tree/bin/generate
 
 The extension generates a `build.Dockerfile` that installs `tree` on the builder image.
 
-### Re-create our builder with `hello-extensions` updated to require `tree`
-
-Edit `$PWD/samples/buildpacks/hello-extensions/bin/detect` to uncomment the first set of lines that output `[[requires]]` to the build plan:
-
-<!-- test:exec -->
-```bash
-sed -i "10,11s/#//" $PWD/samples/buildpacks/hello-extensions/bin/detect
-```
-
-(On Mac, use `sed -i '' "10,11s/#//" $PWD/samples/buildpacks/hello-extensions/bin/detect`)
-
-Re-create the builder:
-
-<!-- test:exec -->
-```
-pack builder create localhost:5000/extensions-builder \
-  --config $PWD/samples/builders/alpine/builder.toml \
-  --publish
-```
-
 ### Re-build the application image
 
 <!-- test:exec -->
 ```
 pack build hello-extensions \
   --builder localhost:5000/extensions-builder \
+  --env BP_EXT_DEMO=1 \
+  --env BP_REQUIRES=tree \
   --network host \
   --path $PWD/samples/apps/java-maven \
   --pull-policy always \

content/docs/extension-guide/create-extension/run-dockerfile.md

@@ -48,32 +48,14 @@ docker build \
   --tag run-image-curl .
 ```
 
-### Re-create our builder with `hello-extensions` updated to require `curl`
-
-Edit `$PWD/samples/buildpacks/hello-extensions/bin/detect` to uncomment the second set of lines that output `[[requires]]` to the build plan:
-
-<!-- test:exec -->
-```bash
-sed -i "14,15s/#//" $PWD/samples/buildpacks/hello-extensions/bin/detect
-```
-
-(On Mac, use `sed -i '' "14,15s/#//" $PWD/samples/buildpacks/hello-extensions/bin/detect`)
-
-Re-create the builder:
-
-<!-- test:exec -->
-```bash
-pack builder create localhost:5000/extensions-builder \
-  --config $PWD/samples/builders/alpine/builder.toml \
-  --publish
-```
-
 ### Re-build the application image
 
 <!-- test:exec -->
 ```bash
 pack build hello-extensions \
   --builder localhost:5000/extensions-builder \
+  --env BP_EXT_DEMO=1 \
+  --env BP_REQUIRES=tree,curl \
   --path $PWD/samples/apps/java-maven \
   --pull-policy always \
   --network host \

content/docs/extension-guide/create-extension/why-dockerfiles.md

@@ -60,6 +60,7 @@ Run `pack build` (note that the "source" directory is effectively ignored in our
 ```
 pack build hello-extensions \
   --builder localhost:5000/extensions-builder \
+  --env BP_EXT_DEMO=1 \
   --network host \
   --path $PWD/samples/apps/java-maven \
   --pull-policy always \