Multi-arch image support

hooks/arches.sh

@@ -0,0 +1,30 @@
+# The default Debian-based SQLite images support these arches.
+#
+# Other images (Alpine-based, or with other database backends) currently
+# support only a subset of these.
+arches=(
+    amd64
+    arm32v6
+    arm32v7
+    arm64v8
+)
+
+case "${DOCKER_REPO}" in
+    *-mysql)
+        db=mysql
+        arches=(amd64)
+        ;;
+    *-postgresql)
+        db=postgresql
+        arches=(amd64)
+        ;;
+    *)
+        db=sqlite
+        ;;
+esac
+
+if [[ "${DOCKER_TAG}" == *alpine ]]; then
+    # The Alpine build currently only works for amd64.
+    os_suffix=.alpine
+    arches=(amd64)
+fi