Install the server headers of the PostgreSQL the runner image ships

.github/actions/provision-meos/action.yml

@@ -69,12 +69,13 @@ runs:
       env:
         PACKAGES: >-
           clang libclang-dev libjson-c-dev libgsl-dev libproj-dev libgeos-dev
-          postgresql-server-dev-16
       run: |
+        # The PostgreSQL server headers are those of the PostgreSQL the image ships.
+        packages="$PACKAGES $(bash "$GITHUB_ACTION_PATH/server-dev-package.sh")"
         image="${ImageOS:-unknown}-${ImageVersion:-unknown}"
-        pkg_hash="$(echo "$PACKAGES" | tr -s ' \n' '\n\n' | sort | sha256sum | cut -c1-16)"
+        pkg_hash="$(echo "$packages" | tr -s ' \n' '\n\n' | sort | sha256sum | cut -c1-16)"
         {
-          echo "packages=$PACKAGES"
+          echo "packages=$packages"
           echo "deb-prefix=provision-meos-sysroot-debs-${ImageOS:-unknown}-"
           echo "deb-key=provision-meos-sysroot-debs-$image-$pkg_hash"
         } >> "$GITHUB_OUTPUT"

.github/actions/provision-meos/server-dev-package.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# server-dev-package.sh — print the package holding the server headers of the PostgreSQL the
+# runner image ships: postgresql-server-dev-16 on ubuntu-24.04 (PostgreSQL 16), and
+# postgresql-server-dev-18 on ubuntu-26.04 (PostgreSQL 18). The major version is the directory
+# the image installs under /usr/lib/postgresql, so the headers libclang reads follow the image
+# instead of a version written into the install lists of this action and of this repository's
+# workflows. postgresql-server-dev-all cannot stand in for it: the images ship postgresql-common
+# from apt.postgresql.org, which the archive's postgresql-server-dev-all does not accept.
+#
+# Usage:
+#   apt-get.sh install -y "$(server-dev-package.sh)"
+set -euo pipefail
+
+major="$(find /usr/lib/postgresql -mindepth 1 -maxdepth 1 -type d -printf '%f\n' 2>/dev/null |
+  grep -E '^[0-9]+$' | sort -n | tail -1 || true)"
+if [ -z "$major" ]; then
+  echo "server-dev-package.sh: the image installs no PostgreSQL under /usr/lib/postgresql" >&2
+  exit 1
+fi
+echo "postgresql-server-dev-$major"

.github/workflows/openapi-validate.yml

@@ -43,7 +43,7 @@ jobs:
           bash .github/actions/provision-meos/apt-get.sh install -y --no-install-recommends \
             clang libclang-dev \
             libjson-c-dev libgsl-dev libproj-dev libgeos-dev \
-            postgresql-server-dev-16
+            "$(bash .github/actions/provision-meos/server-dev-package.sh)"
 
       - name: Clone MobilityDB master (MEOS headers source)
         run: |