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[v0.16.x] disables old kubedns when coredns-local enabled. #1905
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* KIAM updates to support assumeRoleArn functionalilty * Add compute.internal to etcd san when using private zones, because the aws controller does not support private zones * Fix tests * Forced rebuild. Co-authored-by: Dominic Gunn <[email protected]> Co-authored-by: Dominic Gunn <[email protected]>
* KIAM updates to support assumeRoleArn functionalilty * Add compute.internal to etcd san when using private zones, because the aws controller does not support private zones * Fix issue with node names in the clusters * Fix tests * Whitespace. * Forced rebuild. * Update cloud-config-controller * Update cloud-config-controller * Update test * Remove verbose json output. * Allow dnsmasq to be backed by a local copy of CoreDNS This commit allows the user to specify that dnsmasq should be backed by a pod-local copy of CoreDNS rather than relying on the global CoreDNS service. If enabled, the dnsmasq-node DaemonSet will be configured to use a local copy of CoreDNS for its resolution while setting the global CoreDNS service as a fallback. This is handy in situations where the number of DNS requests within a cluster grows large and causes resolution issues as dnsmasq reaches out to the global CoreDNS service. Additionally, several values passed to dnsmasq are now configurable including its `--cache-size` and `--dns-forward-max`. See [this postmortem](https://github.com/zalando-incubator/kubernetes-on-aws/blob/dev/docs/postmortems/jan-2019-dns-outage.md) for an investigation into this situation which was instrumental in understanding issues we were facing. Many thanks to dominicgunn for providing the manifests which I codified into this commit. --- These features can be enabled and tuned by setting the following values within cluster.yaml: ```yaml kubeDns: dnsmasq: coreDNSLocal: # When enabled, this will run a copy of CoreDNS within each DNS-masq pod and # configure the utility to use it for resolution. enabled: true # Defines the resource requests/limits for the coredns-local container. # cpu and/or memory constraints can be removed by setting the appropriate value(s) # to an empty string. resources: requests: cpu: 50m memory: 100Mi limits: cpu: 50m memory: 100Mi # The size of dnsmasq's cache. cacheSize: 50000 # The maximum number of concurrent DNS queries. dnsForwardMax: 500 # This option gives a default value for time-to-live (in seconds) which dnsmasq # uses to cache negative replies even in the absence of an SOA record. negTTL: 60 ``` * Always create required dnsmasq resources The dnsmasq-node ServiceAccount must exist whether or not CoreDNS-local has been enabled. Therefore, it is created alongside the DaemonSet rather than as part of the coredns-local manifest. Additionally, always create dnsmasq-node-coredns-local.yaml If this file does not exist (as would be the case if the CoreDNS local feature has not been enabled), controller nodes will fail to come up with the error: > error: the path "/srv/kubernetes/manifests/dnsmasq-node-coredns-local.yaml" does not exist This is caused when `kubectl delete` is called against the file because of the line `remove "${mfdir}/dnsmasq-node-coredns-local.yaml`. This manifest must always be generated because the CoreDNS-local feature cannot be enabled and then later disabled without otherwise requiring manual operator intervention. Co-authored-by: Dominic Gunn <[email protected]> Co-authored-by: Dominic Gunn <[email protected]> Co-authored-by: Kevin Richardson <[email protected]>
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Sep 16, 2020
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