Improve investigation of containerized builds

The current approach was not actually working as the container was not
start with in interactive bash shell (or any kind of process that would
just keep it running once started).

README.md

@@ -106,10 +106,10 @@ locations.
 Finally, run `podman system migrate` to apply.
 
 ### Investigation of build failures
-By default, `makecontainerpkg` starts the container via `--rm` so the container
-is removed in the end. Set `DEBUG=1` to prevent that. Then one can use e.g.
-`podman container start …` and `podman container exec -it … bash` to enter the
-container for manual investigation.
+By default, `makecontainerpkg` removes the container in the end. Set `DEBUG=1`
+to prevent that. Then one can use e.g. `podman container exec -it … bash` to
+enter the container for manual investigation. Set `DEBUG=on-failure` to only
+keep the container in case of a failure.
 
 ### Using Arch-packages on another distribution via a container
 If you want to cross-compile software on non-Arch distributions you can make use

devel/container/makecontainerpkg

@@ -1,9 +1,13 @@
 #!/bin/bash
 set -e
 
+# make basic arguments for cre
+pkgname=$(grep -oP '(?<=pkgname=).+(?=$)' PKGBUILD | tr '+' 'p')
+uuid=$(cat /proc/sys/kernel/random/uuid)
+name=makechrootpkg-$pkgname-$uuid
+cre_args=(--name "$name" --workdir "/startdir" -v "$PWD":/startdir -it)
+
 # parse arguments
-cre_args=(--workdir "/startdir" -v "$PWD":/startdir)
-[[ $DEBUG ]] || script_args+=(--rm)
 script_args= read_script_args= no_sync=
 for arg in "$@"; do
     if [[ $read_script_args ]]; then
@@ -27,4 +31,21 @@ if ! [[ $no_sync ]]; then
     script_sync=$(cat "$bindir/containersync")
 fi
 
-${CRE:-docker} run "${cre_args[@]}" "${CRE_IMAGE:-archlinux-base-devel}" bash -c "$script_sync $script $script_args"
+# invoke containerized build
+ec=0 cre=${CRE:-docker}
+"$cre" container create "${cre_args[@]}" "${CRE_IMAGE:-archlinux-base-devel}"
+"$cre" container start "$name"
+"$cre" container exec "$name" bash \
+    -c "$script_sync $script $script_args" || ec=$?
+
+# stop and remove container unless we want to keep it for debugging
+[[ $ec == 0 && $DEBUG == on-failure || -z $DEBUG ]] && \
+    "$cre" container rm --force --time 0 "$name"
+
+# log message about commands to use for investigation
+[[ $ec != 0 ]] && [[ $DEBUG ]] && echo \
+    "You may investigate the failure via:
+    $cre exec -it '$name' bash
+    $cre mount '$name'"
+
+exit $ec