Add a Salesforce Functions image variant

We want to move Salesforce Functions buildpacks to their own builder
image variant to more cleanly separate the two use cases (particularly
given that Salesforce Functions is now deprecated), and prevent a number
of issues (such as builds on the functions build system being able to
pass detection even when the match against a non-functions buildpack).

For more details, see:
https://salesforce.quip.com/MoDFAX3MEf8b

The first stage of this is to create the new builder image variant.

This new variant is only being published to the internal private
registry, since it's only being used by Kodon (the SF CLI no longer
supports using containers to run functions).

Once it's released, we can then switch Kodon to using the new tag,
deploy Kodon to all functions instances, and then finally remove the
functions buildpacks from `heroku/builder:22`.

We'll also need to adjust the CNB release automation so that it
updates the new image variant too:
https://github.com/heroku/languages-github-actions/blob/8f1d3319996df5ec9eb3b4c9c7c0d5de78fa9dba/.github/workflows/_buildpacks-release.yml#L315

GUS-W-14179967.

.github/workflows/build-test-publish.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        builder: ["buildpacks-20", "builder-classic-22", "builder-22"]
+        builder: ["buildpacks-20", "builder-classic-22", "builder-22", "salesforce-functions"]
     steps:
       - name: Checkout
         uses: actions/checkout@v3
@@ -32,9 +32,11 @@ jobs:
       # We manually compress the archive rather than relying upon actions/cache's compression, since
       # it ends up being faster both in this job and also later when the images are consumed.
       - name: Export Docker images from the Docker daemon
-        env:
-          BUILDER: ${{ matrix.builder }}
-        run: docker save ${{ matrix.builder }} heroku/heroku:${BUILDER##*-}-cnb | zstd -T0 --long=31 -o images.tar.zst
+        # Using sed rather than yq until this yq bug is fixed:
+        # https://github.com/mikefarah/yq/issues/1758
+        run: |
+          RUN_IMAGE_TAG=$(sed --quiet --regexp-extended --expression 's/run-image\s*=\s*"(.+)"/\1/p' ${{ matrix.builder }}/builder.toml)
+          docker save ${{ matrix.builder }} ${RUN_IMAGE_TAG} | zstd -T0 --long=31 -o images.tar.zst
       # We use a cache here rather than artifacts because it's 4x faster and we
       # don't need the builder archive outside of this workflow run anyway.
       - name: Save Docker images to the cache
@@ -95,7 +97,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        builder: ["builder-22"]
+        builder: ["builder-22", "salesforce-functions"]
         language: ["java", "javascript", "typescript"]
     steps:
       - name: Checkout
@@ -145,6 +147,8 @@ jobs:
           - builder: builder-22
             tag_public: heroku/builder:22
             tag_private: heroku-22:builder
+          - builder: salesforce-functions
+            tag_private: heroku-22:builder-functions
     steps:
       - name: Restore Docker images from the cache
         uses: actions/cache/restore@v3

salesforce-functions/builder.toml

@@ -0,0 +1,27 @@
+description = "Internal builder image for Salesforce Functions"
+
+[stack]
+id = "heroku-22"
+build-image = "heroku/heroku:22-cnb-build"
+run-image = "heroku/heroku:22-cnb"
+
+[lifecycle]
+version = "0.17.1"
+
+[[buildpacks]]
+  id = "heroku/java-function"
+  uri = "docker://docker.io/heroku/buildpack-java-function@sha256:4cbe8d4984f70fc63e6b0fcea1b904d4246d90bbe0b9cc10ba8b73c98eda3b00"
+
+[[buildpacks]]
+  id = "heroku/nodejs-function"
+  uri = "docker://docker.io/heroku/buildpack-nodejs-function@sha256:69d61df4e1805055fcf2911e75f5fed59b02292f2bda7c78b6f891e8d8cd00f3"
+
+[[order]]
+  [[order.group]]
+    id = "heroku/nodejs-function"
+    version = "1.1.6"
+
+[[order]]
+  [[order.group]]
+    id = "heroku/java-function"
+    version = "3.2.0"