fix(cni): make cni logs available via kubectl logs

[slonka]

Signed-off-by: slonka [email protected]

I wrongly assumed that you can't send logs to stdout or stderr. This is not true, logs of "install-cni" can be sent to stderr - kubelet only cares about about stdout. As for "kuma-cni" (the main cni process) to make logs available via "kubectl logs" they need to appear in the daemonset stderr so in this PR we hijack this file descriptor and send logs there.

Example logs:

kubectl logs -n kube-system   kuma-cni-node-gt56p -f
2022-08-17T18:31:13.394Z        DEBUG   install-cni     cni binary file permissions     {"permissions": 493, "path": "/opt/cni/bin/kuma-cni"}

...

2022-08-17T18:31:45.376Z        INFO    kuma-cni        successfully injected iptables rules    {"pod": "demo-app-7458cfdd75-ztgjb", "namespace": "kuma-demo", "podInfraContainerId": "bfe54a320886f00e2f97a6c36cfeabda69a28a0608efbdea0f9adcb291b95389", "ip": "", "containerId": "bfe54a320886f00e2f97a6c36cfeabda69a28a0608efbdea0f9adcb291b95389", "args": "IgnoreUnknown=1;K8S_POD_NAMESPACE=kuma-demo;K8S_POD_NAME=demo-app-7458cfdd75-ztgjb;K8S_POD_INFRA_CONTAINER_ID=bfe54a320886f00e2f97a6c36cfeabda69a28a0608efbdea0f9adcb291b95389"}

...

2022-08-17T18:31:45.565Z        DEBUG   install-cni     config valid    {"file": "/host/etc/cni/net.d/10-flannel.conflist", "name": "cbr0", "plugins": [{"delegate":{"forceAddress":true,"hairpinMode":true,"isDefaultGateway":true},"type":"flannel"},{"capabilities":{"portMappings":true},"type":"portmap"},{"cniVersion":"0.3.1","kubernetes":{"cni_bin_dir":"/bin","exclude_namespaces":["kube-system"],"kubeconfig":"/var/lib/rancher/k3s/agent/etc/cni/net.d/ZZZ-kuma-cni-kubeconfig"},"log_level":"info","name":"kuma-cni","type":"kuma-cni"}]}
2

As you can see we have logs from both install-cni and kuma-cni

Checklist prior to review

• Link to docs PR or issue -- no docs yet
• Link to UI issue or PR -- not a UI issue
• Is the issue worked on linked? -- not reported yet
• The PR does not hardcode values that might break projects that depend on kuma (e.g. "kumahq" as a image registry) -- no
• The PR will work for both Linux and Windows, system specific functions like syscall.Mkfifo have equivalent implementation on the other OS -- CNI only works on linux so this is not relevant
• Unit Tests -- I don't think we have assertions on logs, mentioned in the previous PR
• E2E Tests --
• Manual Universal Tests --
• Manual Kubernetes Tests -- yes on k3d
• Do you need to update UPGRADE.md? --
• Does it need to be backported according to the backporting policy? --

[slonka]

@Mergifyio backport release-1.8

[mergify]

backport release-1.8

✅ Backports have been created

• #4846 fix: make cni logs available via kubectl logs (backport #4845) has been created for branch release-1.8