Dalton Hubble bbbaf949f9 Fix UDP outbound and clock sync timeouts on Azure workers ... * Add "lb" outbound rule for worker TCP _and_ UDP traffic * Fix Azure worker nodes clock synchronization being inactive due to timeouts reaching the CoreOS / Flatcar NTP pool * Fix Azure worker nodes not providing outbount UDP connectivity Background: Azure provides VMs outbound connectivity either by having a public IP or via an SNAT masquerade feature bundled with their virtual load balancing abstraction (in contrast with, say, a NAT gateway). Azure worker nodes have only a private IP, but are associated with the cluster load balancer's backend pool and ingress frontend IP. Outbound traffic uses SNAT with this frontend IP. A subtle detail with Azure SNAT seems to be that since both inbound lb_rule's are TCP only, outbound UDP traffic isn't SNAT'd (highlights the reasons Azure shouldn't have conflated inbound load balancing with outbound SNAT concepts). However, adding a separate outbound rule and disabling outbound SNAT on our ingress lb_rule's we can tell Azure to continue load balancing as before, and support outbound SNAT for worker traffic of both the TCP and UDP protocol. Fixes clock synchronization timeouts: ``` systemd-timesyncd[786]: Timed out waiting for reply from 45.79.36.123:123 (3.flatcar.pool.ntp.org) ``` Azure controller nodes have their own public IP, so controllers (and etcd) nodes have not had clock synchronization or outbound UDP issues		2020-03-31 21:00:16 -07:00
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container-linux/kubernetes	Fix UDP outbound and clock sync timeouts on Azure workers	2020-03-31 21:00:16 -07:00
ignore	Add new tutorial docs and links	2018-08-27 23:30:32 -07:00