prepare for multi-CI

split things out so more can be shared between CIs

push-all

@@ -1,12 +1,15 @@
-#!/bin/sh -eu
+#!/usr/bin/env bash
+#
+# Usage: ./push-all <registry-prefix> <image-tag>
+set -euo pipefail
 
-: "${REGISTRY_URL:=nixpkgs}"
-: "${IMAGE_TAG:=latest}"
+registry_prefix=${1:-nixpkgs}
+image_tag=${2:-latest}
 
 releases_json=$(nix-instantiate ./release.nix --strict --eval --json)
 
 for attr in $(echo "$releases_json" | jq -r "keys[]") ; do
   file=$(echo "$releases_json" | jq -r ".\"$attr\"")
   echo "--- $attr -> $file"
-  skopeo copy "docker-archive://$file" "docker://$REGISTRY_URL/$attr:$IMAGE_TAG"
+  skopeo copy "docker-archive://$file" "docker://$registry_prefix/$attr:$image_tag"
 done