[Felix] Override hostname with determined nodename by default in CalculationGraph init

[DrAuYueng]

Description

When kubelet specifies a hostname using the hostname-override parameter, for example: --hostname-override=192.168.0.10, the result will be different from the result obtained by the hostname command.
This means that the endpointHostnameFilter will filter out node-related event processing.
In this scenario, the hostname needs to be explicitly defined using the environment variable HOSTNAME.
In the calico-node daemonset yaml file, HOSTNAME can be defined using the following configuration:

        - name: HOSTNAME
          valueFrom:
            fieldRef:
              apiVersion: v1
              fieldPath: spec.nodeName

Related issues/PRs

Todos

• Tests
• Documentation
• Release note

Release Note

Override hostname with determined nodename by default in CalculationGraph init.

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[mazdakn]

/sem-approve

[DrAuYueng]

The CI failure seems to be unrelated to the current PR. Is there something I missed?

[mazdakn]

@DrAuYueng no, it's not related to this PR. it's a known issue, and we are working to fix it.
I'm going to review the PR tomorrow.

[DrAuYueng]

The hostname can be specified through the environment variable FELIX_FELIXHOSTNAME, configured as follows:

- name: FELIX_FELIXHOSTNAME
  valueFrom:
    fieldRef:
      apiVersion: v1
      fieldPath: spec.nodeName

, but I hope that automatic detection and processing can be done by default, after all, cni-plugin and calico node startup both do similar processing.

[mazdakn]

@DrAuYueng I do not understand the motivation here. Felix is a process inside Calico node, and it is node's responsibility to auto detect hostname and pass it to Felix (which seems it does).