Comment 19 for bug 1893716

#2 95-hwe-eol / update-motd-hwe-eol

Sadly this already does some caching in update-motd-hwe-eol by checking if the last of these checks is older than an update to the source lists. But to do so it has already executed the - relatively - rather expensive apt-config calls.

Since it comes down to checking new sources.lists there is no need to update this more often than once every few minutes or hours. Could be even slower without loosing most of its value, but we already achieve most of what we need with a delay of ~1h.

We started with:
     5.37% apt-config
Now:
     -- no more present

--- orig/95-hwe-eol 2022-03-30 07:53:18.396529018 +0000
+++ /etc/update-motd.d/95-hwe-eol 2022-03-30 09:13:16.160985148 +0000
@@ -1,5 +1,11 @@
 #!/bin/sh

+# this stamp is created and updated by /usr/lib/update-notifier/update-motd-hwe-eol
+stamp="/var/lib/update-notifier/hwe-eol"
+
+# do not try to refresh this more than once per hour
+find $stamp -newermt 'now-1 hours' 2> /dev/null | grep -m 1 '.' && exit 0
+
 if [ -x /usr/lib/update-notifier/update-motd-hwe-eol ]; then
     exec /usr/lib/update-notifier/update-motd-hwe-eol
 fi

No big need left to reduce the apt-config usage in update-motd-hwe-eol after this change.