Add capability to use swap, requires Kube 1.22 (#8241)

* Alpha-NodeSwap: allow nodes to use swap

* CI: Add Fedora 35 with experimental swap job

.gitlab-ci/packet.yml

@@ -229,6 +229,11 @@ packet_fedora34-calico-selinux:
   extends: .packet_periodic
   when: on_success
 
+packet_fedora35-calico-swap-selinux:
+  stage: deploy-part2
+  extends: .packet_pr
+  when: manual
+
 packet_amazon-linux-2-aio:
   stage: deploy-part2
   extends: .packet_pr

docs/ci.md

@@ -14,7 +14,7 @@ debian11 |  :white_check_mark: | :x: | :x: | :x: | :x: | :x: | :x: | :x: | :x: |
 debian9 |  :x: | :x: | :x: | :x: | :x: | :x: | :white_check_mark: | :x: | :x: |
 fedora33 |  :white_check_mark: | :x: | :x: | :x: | :x: | :x: | :x: | :x: | :x: |
 fedora34 |  :white_check_mark: | :x: | :x: | :x: | :white_check_mark: | :x: | :x: | :x: | :x: |
-fedora35 |  :x: | :x: | :x: | :x: | :x: | :white_check_mark: | :x: | :x: | :x: |
+fedora35 |  :white_check_mark: | :x: | :x: | :x: | :x: | :white_check_mark: | :x: | :x: | :x: |
 opensuse |  :x: | :white_check_mark: | :x: | :x: | :x: | :x: | :x: | :x: | :x: |
 oracle7 |  :x: | :white_check_mark: | :x: | :x: | :x: | :x: | :x: | :x: | :x: |
 ubuntu16 |  :x: | :white_check_mark: | :x: | :white_check_mark: | :x: | :white_check_mark: | :x: | :x: | :x: |

roles/kubernetes/node/templates/kubelet-config.v1beta1.yaml.j2

@@ -106,3 +106,7 @@ eventRecordQPS: {{ kubelet_event_record_qps }}
 shutdownGracePeriod: {{ kubelet_shutdown_grace_period }}
 shutdownGracePeriodCriticalPods: {{ kubelet_shutdown_grace_period_critical_pods }}
 {% endif %}
+{% if not kubelet_fail_swap_on|default(true) %}
+memorySwap:
+  swapBehavior: {{ kubelet_swap_behavior|default("LimitedSwap") }}
+{% endif %}

roles/kubernetes/preinstall/tasks/0010-swapoff.yml

@@ -13,11 +13,17 @@
   command: /sbin/swapon -s
   register: swapon
   changed_when: no
+
 - name: Disable swap
   command: /sbin/swapoff -a
-  when: swapon.stdout
+  when:
+    - swapon.stdout
+    - kubelet_fail_swap_on | default(True)
   ignore_errors: "{{ ansible_check_mode }}"  # noqa ignore-errors
 
 - name: Disable swapOnZram for Fedora
   command: touch /etc/systemd/zram-generator.conf
-  when: swapon.stdout and ansible_distribution in ['Fedora']
+  when:
+    - swapon.stdout
+    - ansible_distribution in ['Fedora']
+    - kubelet_fail_swap_on | default(True)

tests/files/packet_fedora35-calico-swap-selinux.yml

+---
+# Instance settings
+cloud_image: fedora-35
+mode: default
+
+# Kubespray settings
+auto_renew_certificates: true
+
+# Test with SELinux in enforcing mode
+preinstall_selinux_state: enforcing
+
+# Test Alpha swap feature by leveraging zswap default config in Fedora 35
+kubelet_fail_swap_on: False
+kube_feature_gates:
+  - "NodeSwap=True"