Make default builtin-spack-packages-ref from repos.yaml

.github/workflows/README.md

@@ -15,7 +15,7 @@ This workflow handles building and running short CI tests on a given spack manif
 | `spack-compiler-manifest-path` | `string` (Path relative to component repository root) | A file path in the caller model component repository that contains the spack manifest to install local compilers not in the upstream | `false` | N/A | `".github/build/compilers/intel-2021.11.0.spack.yml"` |
 | `spack-manifest-data-pairs` | `string` | An optional, multi-line string of space-separated key-value pairs to fill in `inputs.spack-manifest-path`. This is useful for filling in template values created dynamically by earlier jobs needed by this workflow. This doesn't include `{{ ref }}`, which is filled in automatically. | `false` | N/A | `"package mom5`(newline)`compiler intel"` |
 | `ref` | `string` (Git ref) | The branch, tag, or commit SHA of the caller model component repository | `false` | `github.event.pull_request.head.sha` for PRs, `github.sha` otherwise | `"c0fef23fc1e69d3a31ec18fd8b7102acdf95f651"`, `"main"`, `"2025.01.000"` |
-| `spack-config-ref` | `string` (Git ref) | The branch, tag, or commit SHA of the access-nri/spack-config repository to use | `false` | `"main"` | `"02125b01eb7c778c8d0ae0a02a260de474782e81"`, `"main"`, `"2025.01.000"` |
+| `spack-config-ref` | `string` (Git ref) | The branch, tag, or commit SHA of the access-nri/spack-config repository to use | `false` | Ref in `spack-config`s `repos.yaml`, or `develop` if not specified | `"02125b01eb7c778c8d0ae0a02a260de474782e81"`, `"main"`, `"2025.01.000"` |
 | `builtin-spack-packages-ref` | `string` (Git ref) | The branch, tag, or commit SHA of the `spack/spack-packages` repository to use | `false` | `"main"` | `"f7314790111ec43cf9cff60421c155b922c349ad"`, `"main"`, `"2025.01.000"` |
 | `access-spack-packages-ref` | `string` (Git ref) | The branch, tag, or commit SHA of the `access-nri/access-spack-packages` repository to use | `false` | `"main"` | `"e4ba85db0be4a9b9493cf7581623f9997b9404a5"`, `"main"`, `"2025.01.000"` |
 | `allow-ssh-into-spack-install` | `boolean` | Enable the actor of the workflow to SSH into the container where the spack packages have been installed. This is useful for gathering post-install information before the container is destroyed. This will also make the workflow wait until the actor SSHs into the container, or it times out, before continuing | `false` | `false` | `true`, `false` |

.github/workflows/ci.yml

@@ -52,7 +52,7 @@ on:
       builtin-spack-packages-ref:
         required: false
         type: string
-        default: develop
+        # default: ref from spack-config's repos.yaml, or 'develop' otherwise
         description: |
           The branch, tag, or commit SHA of the spack/spack-packages repository to use.
           For example: main, 2025.03.0, 7ey2uy2.
@@ -300,6 +300,17 @@ jobs:
           echo "----- Packages -----"
           spack find
 
+      - name: Spack - Get builtin ref from spack-config
+        if: inputs.builtin-spack-packages-ref == ''
+        id: get-default-builtin
+        # If inputs.builtin-spack-packages-ref is not provided, get the builtin-spack-packages-ref
+        # from spack-config's repos.yaml or use "develop" (the default branch) if not specified there either.
+        run: |
+          . ${{ steps.env.outputs.SPACK_ROOT }}/share/spack/setup-env.sh
+          ref=$(spack config get repos | yq '.repos.builtin | .branch // .tag // .commit // "develop"')
+          echo "Default builtin-spack-packages-ref is $ref"
+          echo "ref=$ref" >> $GITHUB_OUTPUT
+
       - name: Spack - Get spack-packages repo locations
         id: spack-packages-locations
         run: |
@@ -314,7 +325,7 @@ jobs:
         with:
           spack-packages-repository-name: builtin
           spack-packages-repository-path: ${{ steps.spack-packages-locations.outputs.builtin }}
-          ref: ${{ inputs.builtin-spack-packages-ref }}
+          ref: ${{ inputs.builtin-spack-packages-ref || steps.get-default-builtin.outputs.ref }}
           spack-instance-root-path: ${{ steps.env.outputs.SPACK_ROOT }}
 
       - name: Update - access-spack-package version