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9035: Make Cilium rolling-restart delay/timeout configurable (#9176)

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See #9035
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Tristan 2022-08-22 10:37:44 +01:00 committed by GitHub
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29
docs/cilium.md
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@ -153,3 +153,32 @@ cilium_hubble_metrics:
```
[More](https://docs.cilium.io/en/v1.9/operations/metrics/#hubble-exported-metrics)
## Upgrade considerations
### Rolling-restart timeouts
Cilium relies on the kernel's BPF support, which is extremely fast at runtime but incurs a compilation penalty on initialization and update.
As a result, the Cilium DaemonSet pods can take a significant time to start, which scales with the number of nodes and endpoints in your cluster.
As part of cluster.yml, this DaemonSet is restarted, and Kubespray's [default timeouts for this operation](../roles/network_plugin/cilium/defaults/main.yml)
are not appropriate for large clusters.
This means that you will likely want to update these timeouts to a value more in-line with your cluster's number of nodes and their respective CPU performance.
This is configured by the following values:
```yaml
# Configure how long to wait for the Cilium DaemonSet to be ready again
cilium_rolling_restart_wait_retries_count: 30
cilium_rolling_restart_wait_retries_delay_seconds: 10
```
The total time allowed (count * delay) should be at least `($number_of_nodes_in_cluster * $cilium_pod_start_time)` for successful rolling updates. There are no
drawbacks to making it higher and giving yourself a time buffer to accommodate transient slowdowns.
Note: To find the `$cilium_pod_start_time` for your cluster, you can simply restart a Cilium pod on a node of your choice and look at how long it takes for it
to become ready.
Note 2: The default CPU requests/limits for Cilium pods is set to a very conservative 100m:500m which will likely yield very slow startup for Cilium pods. You
probably want to significantly increase the CPU limit specifically if short bursts of CPU from Cilium are acceptable to you.

4
roles/network_plugin/cilium/defaults/main.yml
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@ -236,3 +236,7 @@ cilium_enable_bpf_clock_probe: true
# -- Whether to enable CNP status updates.
cilium_disable_cnp_status_updates: true
# Configure how long to wait for the Cilium DaemonSet to be ready again
cilium_rolling_restart_wait_retries_count: 30
cilium_rolling_restart_wait_retries_delay_seconds: 10

4
roles/network_plugin/cilium/tasks/apply.yml
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@ -14,8 +14,8 @@
command: "{{ kubectl }} -n kube-system get pods -l k8s-app=cilium -o jsonpath='{.items[?(@.status.containerStatuses[0].ready==false)].metadata.name}'" # noqa 601
register: pods_not_ready
until: pods_not_ready.stdout.find("cilium")==-1
retries: 30
delay: 10
retries: "{{ cilium_rolling_restart_wait_retries_count | int }}"
delay: "{{ cilium_rolling_restart_wait_retries_delay_seconds | int }}"
failed_when: false
when: inventory_hostname == groups['kube_control_plane'][0]