Use semver-prefixed tags for OCI artifacts: (tinkerbell#31)

## Description


Tags now follow the vX.Y.Z-<sha> format (e.g. v0.1.0-abc1234), derived from the latest semver tag on main via git describe, falling back to v0.0.0 when no tag exists. Both ci.yml and release.yml are updated to produce and consume the new format.

Fixes: #

## How Has This Been Tested?





## How are existing users impacted? What migration steps/scripts do we need?





## Checklist:

I have:

- [ ] updated the documentation and/or roadmap (if required)
- [ ] added unit or e2e tests
- [ ] provided instructions on how to upgrade

Author: mergify[bot]

.github/workflows/ci.yml

@@ -352,6 +352,8 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
 
       - name: Load shared config
         run: cat .github/config.env >> "$GITHUB_ENV"
@@ -402,17 +404,20 @@ jobs:
         if: github.ref == 'refs/heads/main'
         uses: oras-project/setup-oras@v1
 
-      - name: Compute short SHA
-        id: short-sha
-        run: echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
+      - name: Compute version tag
+        id: version-tag
+        run: |
+          VERSION=$(git describe --tags --first-parent --abbrev=0 --match 'v[0-9]*' 2>/dev/null || echo "v0.0.0")
+          SHA=${GITHUB_SHA::7}
+          echo "tag=${VERSION}-${SHA}" >> "$GITHUB_OUTPUT"
 
       - name: Push artifacts to GHCR
         if: github.ref == 'refs/heads/main'
         working-directory: out
         run: |
           oras push \
             --artifact-platform linux/${{ matrix.arch }} \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }}-${{ matrix.arch }} \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.version-tag.outputs.tag }}-${{ matrix.arch }} \
             --annotation org.opencontainers.image.source=https://github.com/${{ github.repository }} \
             --annotation org.opencontainers.image.revision=${{ github.sha }} \
             vmlinuz-${{ matrix.arch }} \
@@ -430,6 +435,8 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
 
       - name: Load shared config
         run: cat .github/config.env >> "$GITHUB_ENV"
@@ -444,15 +451,18 @@ jobs:
       - name: Install ORAS
         uses: oras-project/setup-oras@v1
 
-      - name: Compute short SHA
-        id: short-sha
-        run: echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
+      - name: Compute version tag
+        id: version-tag
+        run: |
+          VERSION=$(git describe --tags --first-parent --abbrev=0 --match 'v[0-9]*' 2>/dev/null || echo "v0.0.0")
+          SHA=${GITHUB_SHA::7}
+          echo "tag=${VERSION}-${SHA}" >> "$GITHUB_OUTPUT"
 
       - name: Create multi-arch artifact index
         run: |
           REPO="ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}"
-          SHA="${{ steps.short-sha.outputs.sha }}"
+          TAG="${{ steps.version-tag.outputs.tag }}"
           oras manifest index create \
-            "${REPO}:${SHA}" \
-            "${REPO}:${SHA}-amd64" \
-            "${REPO}:${SHA}-arm64"
+            "${REPO}:${TAG}" \
+            "${REPO}:${TAG}-amd64" \
+            "${REPO}:${TAG}-arm64"

.github/workflows/release.yml

@@ -14,6 +14,8 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
 
       - name: Log in to GHCR
         uses: docker/login-action@v3
@@ -28,20 +30,23 @@ jobs:
       - name: Load shared config
         run: cat .github/config.env >> "$GITHUB_ENV"
 
-      - name: Compute short SHA
-        id: short-sha
-        run: echo "sha=${GITHUB_SHA::7}" >> "$GITHUB_OUTPUT"
+      - name: Compute version tag
+        id: version-tag
+        run: |
+          VERSION=$(git describe --tags --first-parent --abbrev=0 --match 'v[0-9]*' --exclude='${{ github.ref_name }}' 2>/dev/null || echo "v0.0.0")
+          SHA=${GITHUB_SHA::7}
+          echo "tag=${VERSION}-${SHA}" >> "$GITHUB_OUTPUT"
 
       - name: Pull release artifacts (amd64)
         run: |
           oras pull --platform linux/amd64 \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }} \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.version-tag.outputs.tag }} \
             -o artifacts/amd64/
 
       - name: Pull release artifacts (arm64)
         run: |
           oras pull --platform linux/arm64 \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }} \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.version-tag.outputs.tag }} \
             -o artifacts/arm64/
 
       - name: Create GitHub Release
@@ -57,5 +62,5 @@ jobs:
       - name: Tag OCI artifact index with version
         run: |
           oras tag \
-            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.short-sha.outputs.sha }} \
+            ghcr.io/${{ github.repository }}/${{ env.OCI_ARTIFACT_NAME }}:${{ steps.version-tag.outputs.tag }} \
             ${{ github.ref_name }}