WRCP platform responsiveness degrades or reboot loop when app pods trigger

process fork bomb.

Worked on a bug.

Patch 1: Worked on Greg's comments.

Signed-off-by: egoncalv <elisamaraaoki.goncalves@windriver.com>
Change-Id: I0b3bf054f2fae954c99a9e4fe2319fc7dbd250fb
(cherry picked from commit a9c242d409)

doc/source/system_configuration/kubernetes/index.rst

@@ -108,3 +108,12 @@ Console Keyboard Mapping
    :maxdepth: 2
 
    console-keyboard-mapping
+
+------------------------
+Kubernetes Configuration
+------------------------
+
+.. toctree::
+   :maxdepth: 2
+
+   limit-number-of-processes-per-pod

doc/source/system_configuration/kubernetes/limit-number-of-processes-per-pod.rst

@@ -0,0 +1,68 @@
+
+.. _limit-number-of-processes-per-pod:
+
+=================================
+Limit Number of Processes per Pod
+=================================
+
+Kubernetes supports limiting the number of processes per pod. By default,
+|prod| configures Kubernetes with a limit of 10000 pids per pod. Users can
+change this setting to suit their deployment.
+
+For general use case of |prod| it is recommended not to use a limit lower
+than 500 pids per pod.
+
+If deploying |prod-os| application it is recommended not to use a limit
+lower than 2000 pids per pod.
+
+For extended flexibility |prod| allows values between 100 and 65535. Setting
+the value to a smaller number helps protect against a larger number of rogue
+pods. For example using a value of 10000 limits 1 rogue pods to 10000 pids,
+while a value of 500 limits 20 rogue pods to 10000 pids.
+
+If an application needs to create more processes than currently allowed this
+limit should be increased. Note that running multiple containers inside the
+same pod consumes the pids of the same pod.
+
+|CLI| can be used to query and modify the value.
+
+.. rubric:: |proc|
+
+-   Current value can be retrieved using 'system service-parameter-list
+    --service kubernetes' and looking at the 'config' section, parameter named
+    'pod_max_pids'.
+
+    .. code-block:: none
+
+        ~(keystone_admin)]$ system service-parameter-list --service kubernetes
+
+        +--------------------------------------+------------+---------+--------------+-------+-------------+----------+
+        | uuid                                 | service    | section |  name        | value | personality | resource |
+        +--------------------------------------+------------+---------+--------------+-------+-------------+----------+
+        | 32751084-d29b-436d-9ffb-4b153e10f5c5 | kubernetes | config  | pod_max_pids | 750   | None        | None     |
+        +--------------------------------------+------------+---------+--------------+-------+-------------+----------+
+
+-   Value can be modified using: 'system service-parameter-modify kubernetes
+    config pod_pids_limit=<new_value>'.
+
+    .. code-block:: none
+
+        ~(keystone_admin)]$ system service-parameter-modify kubernetes config pod_max_pids=800
+
+        +--------------+--------------------------------------+
+        | Property     | Value                                |
+        +--------------+--------------------------------------+
+        | uuid         | 32751084-d29b-436d-9ffb-4b153e10f5c5 |
+        | service      | kubernetes                           |
+        | section      | config                               |
+        | name         | pod_max_pids                         |
+        | value        | 800                                  |
+        | personality  | None                                 |
+        | resource     | None                                 |
+        +--------------+--------------------------------------+
+
+-   If the value was deleted by mistake, it can be readded using system
+    service-parameter-add kubernetes config pod_max_pids=<new_value>.
+
+-   After modifying, controller and worker nodes need to be locked
+    and unlocked for the new setting to be applied.