[Bug 1902358] Re: Kubernetes service connectivity issue Ubuntu 20.04 + fq queue discipline

[Kai-Heng Feng]

** Package changed: linux (Ubuntu) => systemd (Ubuntu)

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https://bugs.launchpad.net/bugs/1902358

Title:
  Kubernetes service connectivity issue Ubuntu 20.04 + fq queue
  discipline

Status in systemd package in Ubuntu:
  Incomplete

Bug description:
  IMO this is not related to Kubernetes so I filed the bug here.

  **What happened**:
  Processes in container can't connect to `kubernetes.default` service.

  **What you expected to happen**:
  It should be able to connect.

  **How to reproduce it (as minimally and precisely as possible)**:
  ```bash
  host# tc qdisc add dev eth0 root fq
  host# nsenter -n -t $(pidof some-process-in-container)
  container-net-ns# nc -vv 10.97.0.1 443  # Could not connect
  ```

  **Anything else we need to know?**:
  ```bash
  host# tc qdisc add dev eth0 root noqueue  # this works
  host# tc qdisc add dev eth0 root fq_codel  # this works too
  ```
  - `host` is where the workload container is, not Kubernetes master.
  - When the bug condition is met, packets won't be sent on wire.
  - kube-proxy works in IPVS mode.
  - The reason to tinker with qdisc is to enable TCP BBR, which requires fq qdisc.
  - fq qdisc works in `Linux node1 4.15.0-106-generic #107-Ubuntu SMP Thu Jun 4 11:27:52 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux (Ubuntu 18.04)`

  **Environment**:
  - Cloud provider or hardware configuration: `NIC: Intel X520-DA1 (82599)`
  - OS (e.g: `cat /etc/os-release`): `Ubuntu 20.04.1 LTS \n \l`
  - Kernel (e.g. `uname -a`): `Linux Proton 5.4.0-52-generic #57-Ubuntu SMP Thu Oct 15 10:57:00 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux`
  - Install tools:
  - Network plugin and version (if this is a network-related bug): `Calico v3.14.1 with IPIP & NAT-Outgoing`
  - Others:

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