Add new service "file_tracker"

This new service periodically tracks the file open in the system.

Closes-Bug: #1995502
Change-Id: I02e097fef07655ff571af9f35bf258b2ed975098

.zuul.yaml

@@ -469,6 +469,7 @@
         dstat: false
         etcd3: true
         memory_tracker: true
+        file_tracker: true
         mysql: true
         rabbit: true
     group-vars:
@@ -477,6 +478,7 @@
           # Shared services
           dstat: false
           memory_tracker: true
+          file_tracker: true
         devstack_localrc:
           # Multinode specific settings
           HOST_IP: "{{ hostvars[inventory_hostname]['nodepool']['private_ipv4'] }}"
@@ -544,6 +546,7 @@
         dstat: false
         etcd3: true
         memory_tracker: true
+        file_tracker: true
         mysql: true
         rabbit: true
         tls-proxy: true
@@ -593,6 +596,7 @@
           # Shared services
           dstat: false
           memory_tracker: true
+          file_tracker: true
           tls-proxy: true
           # Nova services
           n-cpu: true

doc/source/debugging.rst

@@ -20,6 +20,12 @@ provides consumption output when available memory is seen to be
 falling (i.e. processes are consuming memory).  It also provides
 output showing locked (unswappable) memory.
 
+file_tracker
+------------
+
+The ``file_tracker`` service periodically monitors the number of
+open files in the system.
+
 tcpdump
 -------
 

lib/dstat

@@ -40,12 +40,18 @@ function start_dstat {
     if is_service_enabled peakmem_tracker; then
         die $LINENO "The peakmem_tracker service has been removed, use memory_tracker instead"
     fi
+
+    # To enable file_tracker add:
+    #    enable_service file_tracker
+    # to your localrc
+    run_process file_tracker "$TOP_DIR/tools/file_tracker.sh"
 }
 
 # stop_dstat() stop dstat process
 function stop_dstat {
     stop_process dstat
     stop_process memory_tracker
+    stop_process file_tracker
 }
 
 # Restore xtrace

tools/file_tracker.sh

@@ -0,0 +1,47 @@
+#!/bin/bash
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+set -o errexit
+
+# time to sleep between checks
+SLEEP_TIME=20
+
+function tracker {
+    echo "Number of open files | Number of open files not in use | Maximum number of files allowed to be opened"
+    while true; do
+        cat /proc/sys/fs/file-nr
+        sleep $SLEEP_TIME
+    done
+}
+
+function usage {
+    echo "Usage: $0 [-x] [-s N]" 1>&2
+    exit 1
+}
+
+while getopts ":s:x" opt; do
+    case $opt in
+        s)
+            SLEEP_TIME=$OPTARG
+            ;;
+        x)
+            set -o xtrace
+            ;;
+        *)
+            usage
+            ;;
+    esac
+done
+
+tracker