POC: add smart index updating

cdist/conf/type/__package_apt/explorer/index

@@ -0,0 +1,9 @@
+#!/bin/sh -e
+
+if [ ! -d /var/lib/apt/lists ] \
+    || [ -n "$( find /etc/apt -mindepth 1 -cnewer /var/lib/apt/lists )" ] \
+    || [ ! -f /var/cache/apt/pkgcache.bin ] \
+    || [ "$( stat --format %Y /var/cache/apt/pkgcache.bin )" -lt "$( date +%s -d '-1 day' )" ]
+then
+    echo 'update'
+fi

cdist/conf/type/__package_apt/gencode-remote

@@ -92,15 +92,9 @@ case "$state_should" in
         # See more: ticket #861
         # https://code.ungleich.ch/ungleich-public/cdist/-/issues/861
         apt_opts="-o Acquire::AllowReleaseInfoChange::Suite=true -o Acquire::AllowReleaseInfoChange::Version=true"
-
+        if [ "$(cat "$__object/explorer/index")" = 'update' ]; then
-        # following is bit ugly, but important hack.
+            echo "apt-get $apt_opts update || true"
-        # due to how cdist config run works, there isn't
-        # currently better way to do it :(
-        cat << EOF
-if [ ! -f /var/cache/apt/pkgcache.bin ] || [ "\$( stat --format %Y /var/cache/apt/pkgcache.bin )" -lt "\$( date +%s -d '-1 day' )" ]
-then echo apt-get $apt_opts update > /dev/null 2>&1 || true
         fi
-EOF
         if [ -n "$version" ]; then
             name="${name}=${version}"
         fi