ci: detect Go backwards compatibility test version automatically

For our submodules and other places we choose to test against previous
Go versions, detect this version automatically from the current one
rather than hard-coding it.

.github/workflows/go-tests.yml

@@ -408,9 +408,11 @@ jobs:
       consul-license: ${{secrets.CONSUL_LICENSE}}
       datadog-api-key: "${{ !endsWith(github.repository, '-enterprise') && secrets.DATADOG_API_KEY || '' }}"
 
-  go-test-api-1-19:
+  go-test-api-backwards-compatibility:
+    name: go-test-api-${{ needs.get-go-version.outputs.go-version-previous }}
     needs:
     - setup
+    - get-go-version
     - dev-build
     uses: ./.github/workflows/reusable-unit.yml
     with:
@@ -418,7 +420,7 @@ jobs:
       runs-on: ${{ needs.setup.outputs.compute-large }}
       repository-name: ${{ github.repository }}
       go-tags: "${{ github.event.repository.name == 'consul-enterprise' && 'consulent consuldev' || '' }}"
-      go-version: "1.19"
+      go-version: ${{ needs.get-go-version.outputs.go-version-previous }}
     permissions:
       id-token: write # NOTE: this permission is explicitly required for Vault auth.
       contents: read
@@ -427,9 +429,10 @@ jobs:
       consul-license: ${{secrets.CONSUL_LICENSE}}
       datadog-api-key: "${{ !endsWith(github.repository, '-enterprise') && secrets.DATADOG_API_KEY || '' }}"
 
-  go-test-api-1-20:
+  go-test-api:
     needs:
     - setup
+    - get-go-version
     - dev-build
     uses: ./.github/workflows/reusable-unit.yml
     with:
@@ -437,7 +440,7 @@ jobs:
       runs-on: ${{ needs.setup.outputs.compute-large }}
       repository-name: ${{ github.repository }}
       go-tags: "${{ github.event.repository.name == 'consul-enterprise' && 'consulent consuldev' || '' }}"
-      go-version: "1.20"
+      go-version: ${{ needs.get-go-version.outputs.go-version }}
     permissions:
       id-token: write # NOTE: this permission is explicitly required for Vault auth.
       contents: read
@@ -446,9 +449,11 @@ jobs:
       consul-license: ${{secrets.CONSUL_LICENSE}}
       datadog-api-key: "${{ !endsWith(github.repository, '-enterprise') && secrets.DATADOG_API_KEY || '' }}"
 
-  go-test-sdk-1-19:
+  go-test-sdk-backwards-compatibility:
+    name: go-test-sdk-${{ needs.get-go-version.outputs.go-version-previous }}
     needs:
     - setup
+    - get-go-version
     - dev-build
     uses: ./.github/workflows/reusable-unit.yml
     with:
@@ -456,7 +461,7 @@ jobs:
       runs-on: ${{ needs.setup.outputs.compute-large }}
       repository-name: ${{ github.repository }}
       go-tags: "${{ github.event.repository.name == 'consul-enterprise' && 'consulent consuldev' || '' }}"
-      go-version: "1.19"
+      go-version: ${{ needs.get-go-version.outputs.go-version-previous }}
     permissions:
       id-token: write # NOTE: this permission is explicitly required for Vault auth.
       contents: read
@@ -465,9 +470,10 @@ jobs:
       consul-license: ${{secrets.CONSUL_LICENSE}}
       datadog-api-key: "${{ !endsWith(github.repository, '-enterprise') && secrets.DATADOG_API_KEY || '' }}"
 
-  go-test-sdk-1-20:
+  go-test-sdk:
     needs:
     - setup
+    - get-go-version
     - dev-build
     uses: ./.github/workflows/reusable-unit.yml
     with:
@@ -475,7 +481,7 @@ jobs:
       runs-on: ${{ needs.setup.outputs.compute-large }}
       repository-name: ${{ github.repository }}
       go-tags: "${{ github.event.repository.name == 'consul-enterprise' && 'consulent consuldev' || '' }}"
-      go-version: "1.20"
+      go-version: ${{ needs.get-go-version.outputs.go-version }}
     permissions:
       id-token: write # NOTE: this permission is explicitly required for Vault auth.
       contents: read
@@ -521,10 +527,10 @@ jobs:
     - go-test-race
     - go-test-envoyextensions
     - go-test-troubleshoot
-    - go-test-api-1-19
-    - go-test-api-1-20
-    - go-test-sdk-1-19
-    - go-test-sdk-1-20
+    - go-test-api-backwards-compatibility
+    - go-test-api
+    - go-test-sdk-backwards-compatibility
+    - go-test-sdk
     - go-test-32bit
     # - go-test-s390x
     runs-on: ${{ fromJSON(needs.setup.outputs.compute-small) }}

.github/workflows/reusable-get-go-version.yml

@@ -6,6 +6,9 @@ on:
       go-version:
         description: "The Go version detected by this workflow"
         value: ${{ jobs.get-go-version.outputs.go-version }}
+      go-version-previous:
+        description: "The Go version (MAJOR.MINOR) prior to the current one, used for backwards compatibility testing"
+        value: ${{ jobs.get-go-version.outputs.go-version-previous }}
 
 jobs:
   get-go-version:
@@ -13,6 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     outputs:
       go-version: ${{ steps.get-go-version.outputs.go-version }}
+      go-version-previous: ${{ steps.get-go-version.outputs.go-version-previous }}
     steps:
       - uses: actions/checkout@c85c95e3d7251135ab7dc9ce3241c5835cc595a9 # v3.5.3
       - name: Determine Go version
@@ -32,3 +36,7 @@ jobs:
           GO_VERSION=$(head -n 1 .go-version)
           echo "Building with Go ${GO_VERSION}"
           echo "go-version=${GO_VERSION}" >> $GITHUB_OUTPUT
+          GO_MINOR_VERSION=${GO_VERSION%.*}
+          GO_VERSION_PREVIOUS="${GO_MINOR_VERSION%.*}.$((${GO_MINOR_VERSION#*.}-1))"
+          echo "Previous version ${GO_VERSION_PREVIOUS}"
+          echo "go-version-previous=${GO_VERSION_PREVIOUS}" >> $GITHUB_OUTPUT