ci(bin-image): clean up env var handling

There are still messy special cases (e.g. DOCKER_GITCOMMIT vs VERSION),
but this makes things a little easier to follow, as we keep
GHA-specifics in the GHA files.

Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>
(cherry picked from commit ad91fc1b0014a68efc660243288f4e65111794de)
Signed-off-by: Bjorn Neergaard <bjorn.neergaard@docker.com>

.github/workflows/bin-image.yml

@@ -16,6 +16,8 @@ on:
 
 env:
   MOBYBIN_REPO_SLUG: moby/moby-bin
+  DOCKER_GITCOMMIT: ${{ github.sha }}
+  VERSION: ${{ github.ref }}
   PLATFORM: Moby Engine
   PRODUCT: Moby
   DEFAULT_PRODUCT_LICENSE: Moby
@@ -113,8 +115,6 @@ jobs:
         name: Build
         id: bake
         uses: docker/bake-action@v3
-        env:
-          DOCKER_GITCOMMIT: ${{ github.sha }}
         with:
           files: |
             ./docker-bake.hcl

docker-bake.hcl

@@ -47,18 +47,6 @@ variable "PACKAGER_NAME" {
   default = ""
 }
 
-# GITHUB_REF is the actual ref that triggers the workflow and used as version
-# when tag is pushed: https://docs.github.com/en/actions/learn-github-actions/environment-variables#default-environment-variables
-variable "GITHUB_REF" {
-  default = ""
-}
-
-# GITHUB_SHA is the commit SHA that triggered the workflow and used as commit.
-# https://docs.github.com/en/actions/learn-github-actions/environment-variables#default-environment-variables
-variable "GITHUB_SHA" {
-  default = ""
-}
-
 # Special target: https://github.com/docker/metadata-action#bake-definition
 target "docker-metadata-action" {
   tags = ["moby-bin:local"]
@@ -81,8 +69,8 @@ target "_common" {
     DOCKER_STATIC = DOCKER_STATIC
     DOCKER_LDFLAGS = DOCKER_LDFLAGS
     DOCKER_BUILDTAGS = DOCKER_BUILDTAGS
-    DOCKER_GITCOMMIT = DOCKER_GITCOMMIT != null ? DOCKER_GITCOMMIT : GITHUB_SHA
-    VERSION = VERSION != "" ? VERSION : GITHUB_REF
+    DOCKER_GITCOMMIT = DOCKER_GITCOMMIT
+    VERSION = VERSION
     PLATFORM = PLATFORM
     PRODUCT = PRODUCT
     DEFAULT_PRODUCT_LICENSE = DEFAULT_PRODUCT_LICENSE