diff --git a/docker/build-image.sh b/docker/build-image.sh
new file mode 100755
index 00000000..0f4c015d
--- /dev/null
+++ b/docker/build-image.sh
@@ -0,0 +1,21 @@
+#!/bin/bash
+
+set -eux
+
+build () {
+  if [ "${ARCH}" = "amd64" ]; then
+    docker build . -t "ghcr.io/alphagov/${APP}:${1}" -f "Dockerfile"
+  else
+    docker buildx build --platform "linux/${ARCH}" . -t "ghcr.io/alphagov/${APP}:${1}" -f "Dockerfile"
+  fi
+}
+
+DOCKER_TAG="${GITHUB_SHA}"
+
+build "${DOCKER_TAG}"
+
+if [[ -n ${DRY_RUN:-} ]]; then
+  echo "Dry run; not pushing to registry"
+else
+  docker push "ghcr.io/alphagov/${APP}:${DOCKER_TAG}"
+fi