Disable updater jitter when run from anacron. (#17826)

* Disable updater jitter when run from anacron.

* Adjust checking to account for busybox ps.

* Check process grandparents as well to handle the use of run-parts.

* Make anacron check more portable.

On Linux when procfs is mounted, use that instead of `ps` because some
older Linux systems apparently don’t support the `ppid` field in `ps`.

Also, allow a variable number of spaces prior to the PID when parsing
`ps` output, as this is less portable than I first realized.

* Address a few additional issues in the detection code.

* Fix additional regexes when parsing ps output.

1 files changed, 32 insertions, 0 deletions

diff --git a/packaging/installer/netdata-updater.sh b/packaging/installer/netdata-updater.sh
index 4fb45bce5d..2fdc0e2709 100755
--- a/packaging/installer/netdata-updater.sh
+++ b/packaging/installer/netdata-updater.sh
@@ -149,6 +149,32 @@ issystemd() {
   return 1
 }
 
+# shellcheck disable=SC2009
+running_under_anacron() {
+    if [ "$(uname -s)" = "Linux" ] && [ -r "/proc/$$/stat" ]; then
+        ppid="$(cut -f 4 -d ' ' "/proc/$$/stat")"
+        if [ -n "${ppid}" ] && [ -r "/proc/${ppid}/comm" ]; then
+            grep -q anacron "/proc/${ppid}/comm" && return 0
+
+            ppid2="$(cut -f 4 -d ' ' "/proc/${ppid}/stat")"
+
+            if [ -n "${ppid2}" ] && [ -r "/proc/${ppid2}/comm" ]; then
+                grep -q anacron "/proc/${ppid2}/comm" 2>/dev/null && return 0
+            fi
+        fi
+    else
+        ppid="$(ps -o pid= -o ppid= 2>/dev/null | grep -e "^ *$$" | xargs | cut -f 2 -d ' ')"
+        if [ -n "${ppid}" ]; then
+            ps -o pid= -o command= 2>/dev/null | grep -e "^ *${ppid}" | grep -q anacron && return 0
+
+            ppid2="$(ps -o pid= -o ppid= 2>/dev/null | grep -e "^ *${ppid}" | xargs | cut -f 2 -d ' ')"
+            ps -o pid= -o command= 2>/dev/null | grep -e "^ *${ppid2}" | grep -q anacron && return 0
+        fi
+    fi
+
+    return 1
+}
+
 _get_intervaldir() {
   if [ -d /etc/cron.daily ]; then
     echo /etc/cron.daily
@@ -1081,6 +1107,12 @@ if [ -n "${NETDATA_OFFLINE_INSTALL_SOURCE}" ]; then
   NETDATA_FORCE_UPDATE=1
 fi
 
+# If we seem to be running under anacron, act as if we’re not running from cron.
+# This is mostly to disable jitter, which should not be needed when run from anacron.
+if running_under_anacron; then
+  NETDATA_NOT_RUNNING_FROM_CRON="${NETDATA_NOT_RUNNING_FROM_CRON:-1}"
+fi
+
 # Random sleep to alleviate stampede effect of Agents upgrading
 # and disconnecting/reconnecting at the same time (or near to).
 # But only we're not a controlling terminal (tty)