CoreDNS is the default plug-in used to implement Domain Name System (DNS)-based service discovery in Container Service for Kubernetes (ACK) clusters and ACK edge clusters. The topic introduces CoreDNS and describes the usage notes and release notes for CoreDNS.

Introduction

CoreDNS is a plug-in used to implement DNS-based service discovery in ACK clusters and ACK edge clusters. CoreDNS follows the specifications of DNS-based service discovery in Kubernetes. For more information, see Kubernetes DNS-Based service discovery. CoreDNS provides DNS resolution capabilities within Kubernetes clusters. ACK maintains a mapping between CoreDNS versions and Kubernetes versions. When you create or update a Kubernetes cluster, the CoreDNS version that is installed or updated depends on the Kubernetes version of the cluster. For more information about the mapping, see CoreDNS version in Kubernetes.

Instructions

For more information about the features and usage notes of CoreDNS, see Configure DNS resolution.
Notice
Before you update CoreDNS, take note of the following items:

Release notes

April 2022

Version Applicable cluster Image address Release date Description Impact
v1.8.4.5-2ce07fd2-aliyun ACK managed clusters, ACK dedicated clusters, and serverless Kubernetes (ASK) clusters that run Kubernetes 1.20.4 or later registry.{{.Region}}.aliyuncs.com/acs/coredns:v1.8.4.5-2ce07fd2-aliyun 2022-04-08 Affinity settings are optimized for the scheduling of CoreDNS. This allows you to deploy CoreDNS in a cluster where each node has auto scaling enabled. No impact on workloads

February 2022

Version Applicable cluster Image address Release date Description Impact
v1.8.4.3-644f4735-aliyun ACK managed clusters, ACK dedicated clusters, and ASK clusters that run Kubernetes 1.20.4 or later registry.{{.Region}}.aliyuncs.com/acs/coredns:v1.8.4.3-644f4735-aliyun 2022-02-22
  • Caching for DNS resolution results of the ServError type is disabled.
  • Pod anti-affinity settings based on hostnames are changed from preferred to required. The system is forced to schedule pods based on the anti-affinity settings.
The system is forced to schedule pods based on the anti-affinity settings. If the number of CoreDNS pods is greater than that of nodes, some CoreDNS pods change to the Pending state. You must scale out cluster nodes or scale in CoreDNS pods before you update to this image version.

January 2022

Version Applicable cluster Image address Release date Description Impact
v1.8.4.2-7d597cff-aliyun ACK managed clusters, ACK dedicated clusters, and serverless Kubernetes (ASK) clusters that run Kubernetes 1.20.4 or later registry.{{.Region}}.aliyuncs.com/acs/coredns:v1.8.4.2-3a376cc-aliyun 2022-01-10
  • Custom parameters are supported.
  • By default, log parsing is enabled.
No impact on workloads

October 2021

Version Applicable cluster Image address Release date Description Impact
v1.8.4.1-3a376cc-aliyun ACK managed clusters, ACK dedicated clusters, and serverless Kubernetes (ASK) clusters that run Kubernetes 1.20.4 or later registry.{{.Region}}.aliyuncs.com/acs/coredns:v1.8.4.1-3a376cc-aliyun 2021-10-26
  • EndpointSlice objects can be monitored.
  • IPv6 addresses are supported by DNS resolutions.
No impact on workloads

July 2021

Version Applicable cluster Image address Release date Description Impact
v1.7.0.0-f59c03d-aliyun ACK managed clusters, ACK dedicated clusters, and ASK clusters registry.{{.Region}}.aliyuncs.com/acs/coredns:v1.7.0.0-f59c03d-aliyun 2021-07-08
  • The default duration of graceful shutdown for CoreDNS and the memory limit of containers in the CoreDNS Deployment are modified.
  • The names of metrics are updated. If your monitoring system is reliant on CoreDNS metrics, you must update the metric names. For more information, see Metric changes.
  • The issue that only the first upstream DNS server specified in the forward plug-in is used is fixed.
  • The deprecated upstream plug-in is no longer compatible. If the upstream plug-in is specified in the Corefile configurations, the upstream plug-in will be automatically deleted in a secure way when CoreDNS is updated.
If you modify the DNS configuration file /etc/resolv.conf on your Elastic Compute Service (ECS) instance, CoreDNS pods are updated or recreated based on the modified /etc/resolv.conf file. You must make sure that the DNS servers specified in this file work as normal before you update CoreDNS.

April 2021

Version Applicable cluster Image address Release date Description Impact
1.6.7.edge ACK edge clusters registry.{{.Region}}.aliyuncs.com/acs/coredns:1.6.7.edge 2021-04-23 This version is optimized based on open source CoreDNS 1.6.7. For more information, see CoreDNS-1.6.7 release. No impact on workloads

March 2021

Version Applicable cluster Image address Release date Description Impact
1.7.0 ACK managed clusters, ACK dedicated clusters, and ASK clusters registry.{{.Region}}.aliyuncs.com/acs/coredns:1.7.0 2021-03-18
  • The deprecated upstream plug-in is no longer compatible. If the upstream plug-in is specified in the Corefile configurations, the upstream plug-in will be automatically deleted in a secure way when CoreDNS is updated.
  • The names of metrics are updated. If your monitoring system is reliant on CoreDNS metrics, you must update the metric names. For more information, see Metric changes.
  • The issue that only the first upstream DNS server specified in the forward plug-in is used is fixed.
If you modify the DNS configuration file /etc/resolv.conf on your ECS instance, CoreDNS pods are updated or recreated based on the modified /etc/resolv.conf file. You must make sure that the DNS servers specified in this file work as normal before you update CoreDNS.

November 2018

Version Applicable cluster Image address Release date Description Impact
1.6.7 ACK managed clusters, ACK dedicated clusters, and ASK clusters registry.{{.Region}}.aliyuncs.com/acs/coredns:1.6.7 2018-11-28 This version is optimized based on open source CoreDNS 1.6.7. For more information, see CoreDNS-1.6.7 release. No impact on workloads