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

Introduction

CoreDNS is the default plug-in used to implement DNS-based service discovery in ACK clusters and edge Kubernetes clusters. CoreDNS complies with 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 upgrade a Kubernetes cluster, the CoreDNS version that is installed or upgraded depends on the Kubernetes version of the cluster. For more information about the mapping, see CoreDNS version in Kubernetes.

Usage notes

For more information about the features and usage notes of CoreDNS, see Introduce and configure the DNS service in ACK clusters.
Notice
Before you upgrade CoreDNS, take note of the following items:
  • Read and understand the CoreDNS upgrade considerations. For more information, see Precautions for upgrading CoreDNS.
  • Back up the CoreDNS ConfigMap in the kube-system namespace.

Release notes

October 2021

Version Applicable cluster Image address Release date Description Impact
v1.8.4.1-3a376cc-aliyun Managed Kubernetes clusters, dedicated Kubernetes 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 Managed Kubernetes clusters, dedicated Kubernetes 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 upgraded.
If you modify the DNS configuration file /etc/resolv.conf on your Elastic Compute Service (ECS) instance, CoreDNS pods are upgraded 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 upgrade CoreDNS.

April 2021

Version Applicable cluster Image address Release date Description Impact
1.6.7.edge Edge Kubernetes 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 Managed Kubernetes clusters, dedicated Kubernetes 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 upgraded.
  • 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 upgraded 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 upgrade CoreDNS.

November 2018

Version Applicable cluster Image address Release date Description Impact
1.6.7 Managed Kubernetes clusters, dedicated Kubernetes 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