Commits on Apr 18, 2018

1. Switch GCP network lb to global TCP proxy lb …

   * Allow multi-controller clusters on Google Cloud
   * GCP regional network load balancers have a long open
   bug in which requests originating from a backend instance
   are routed to the instance itself, regardless of whether
   the health check passes or not. As a result, only the 0th
   controller node registers. We've recommended just using
   single master GCP clusters for a while
   * https://issuetracker.google.com/issues/67366622
   * Workaround issue by switching to a GCP TCP Proxy load
   balancer. TCP proxy lb routes traffic to a backend service
   (global) of instance group backends. In our case, spread
   controllers across 3 zones (all regions have 3+ zones) and
   organize them in 3 zonal unmanaged instance groups that
   serve as backends. Allows multi-controller cluster creation
   * GCP network load balancers only allowed legacy HTTP health
   checks so kubelet 10255 was checked as an approximation of
   controller health. Replace with TCP apiserver health checks
   to detect unhealth or unresponsive apiservers.
   * Drawbacks: GCP provision time increases, tailed logs now
   timeout (similar tradeoff in AWS), controllers only span 3
   zones instead of the exact number in the region
   * Workaround in Typhoon has been known and posted for 5 months,
   but there still appears to be no better alternative. Its
   probably time to support multi-master and accept the downsides

   

   dghubble committed Apr 18, 2018
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