Update Kubernetes from v1.9.3 to v1.9.4

[dghubble]

https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG-1.9.md#v194

Notice

Upstream made a breaking change kubernetes/kubernetes#58720. It impacts the Grafana addon.

"Secret, configMap, downwardAPI and projected volumes will be mounted as read-only volumes. Applications that attempt to write to these volumes will receive read-only filesystem errors. Previously, applications were allowed to make changes to these volumes, but those changes were reverted at an arbitrary interval by the system. Applications should be re-configured to write derived files to another location."

Grafana attempts to chown any dashboards its given, so I'm not sure of the workaround.

[dghubble]

I'm unhappy upstream shipped kubernetes/kubernetes#58720, but introducing feature gates at this late stage is even worse. Given the choice between vanilla v1.9.4 (broken Grafana) and v1.9.4 with a feature gate to rip out the breakage (but undo security fix?) I'm going with vanilla v1.9.4.

However, I've checked that you can still deploy Grafana v4.6.3. Checkout Typhoon v1.9.3 and Grafana works just fine on v1.9.4 clusters. I'll add something in the release notes about Grafana v5.0 being unusuable 😭

[dghubble]

grafana/grafana-docker#140

[dghubble]

Another known issue is that subPath seems to have regressed. kubernetes/kubernetes#61076