Flannel is a Container Network Interface (CNI) plugin that provides VPC-based networking for pod-to-pod communication in ACK clusters.
Overview
Flannel allocates a pod CIDR block independent of the Virtual Private Cloud (VPC) CIDR block and forwards packets through the VPC route table. This eliminates tunneling such as VXLAN and improves network efficiency over Flannel's default VXLAN mode. In ACK, Flannel runs in alloc mode, which cannot be changed after the cluster is created. See Network overview.
Usage notes
Flannel is a stable, open-source
CNI plugin.
Combined with the high-speed VPC network, it delivers high-performance and stable container networking.
Version compatibility
The following table lists the active Flannel version for each Kubernetes version:
| Kubernetes version |
Active Flannel version |
| 1.35 or later |
v0.28.0.6 |
| 1.26 to 1.34 |
v0.15.1.23-33d25c1-aliyun |
| Earlier than 1.26 |
v0.15.1.22-20a397e6-aliyun |
Release notes
March 2026
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.28.0.6 |
registry-cn-hangzhou.ack.aliyuncs.com/acs/flannel:v0.28.0.6 |
March 2, 2026 |
- Upgraded the cni-plugin version to support nftables mode switching.
- Fixed multiple CVE vulnerabilities.
|
Applies to clusters running Kubernetes 1.35 or later. Earlier clusters continue to use v0.15.1.23-33d25c1-aliyun. |
May 2024
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.23-33d25c1-aliyun |
registry-cn-hangzhou.ack.aliyuncs.com/acs/flannel:v0.15.1.23-33d25c1-aliyun |
May 20, 2024 |
Improved Flannel compatibility on Windows. |
Applies to clusters running Kubernetes 1.26 or later. Earlier clusters continue to use v0.15.1.22-20a397e6-aliyun. |
December 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.22-20a397e6-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.22-20a397e6-aliyun |
December 6, 2022 |
Changed the DaemonSet update policy from OnDelete to RollingUpdate. |
After updating to this version, manual YAML changes are automatically applied to all Flannel pods through a rolling update. No pod deletion required. For more information about the update policy, see DaemonSet update strategy. |
October 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.19-d460293f-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.19-d460293f-aliyun |
October 27, 2022 |
- Added compatibility when the CNIVersion field is missing.
- Fixed the CVE-2021-45079 vulnerability.
|
No impact on workloads. |
September 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.18-6f371e73-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.18-6f371e73-aliyun |
September 26, 2022 |
Disabled Node Informer by default to improve performance. |
No impact on workloads. |
August 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.13-941db231-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.13-941db231-aliyun |
August 29, 2022 |
Fixed the CVE-2022-37434 vulnerability. |
No impact on workloads. |
July 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.11-7e95fe23-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.11-7e95fe23-aliyun |
July 28, 2022 |
Changed the default IP address cache directory to /var/run to prevent IP leaks caused by node restarts. |
No impact on workloads. |
May 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.8-1634a106-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.8-1634a106-aliyun |
May 10, 2022 |
Fixed the CVE-2022-28391 vulnerability. |
No impact on workloads. |
April 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.6-a320565c-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.6-a320565c-aliyun |
April 8, 2022 |
Added an init container for Flannel installation. |
No impact on workloads. |
January 2022
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.5-11d1c700-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.5-11d1c700-aliyun |
January 25, 2022 |
Added support for ARM64 instances. |
No impact on workloads. |
December 2021
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.15.1.4-e02c8f12-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.15.1.4-e02c8f12-aliyun |
December 1, 2021 |
- Updated the API version for Authorization and other resources to support Kubernetes 1.22.
- Added support for exposing services through HostPort.
- Enabled hairpin mode by default. Earlier versions of Flannel disable hairpin mode by default. To enable hairpin mode manually in an earlier version, see How do I enable a pod to access a Service that is used to expose the pod?.
|
No impact on workloads. |
May 2021
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.13.0.1-466064b-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.13.0.1-466064b-aliyun |
May 24, 2021 |
- Added adaptive iptables support, compatible with CentOS 8 and Alibaba Cloud Linux 3 and later.
- Added proactive checks and automatic correction of IP forwarding configurations.
|
No impact on workloads. |
August 2019
| Version |
Image address |
Release date |
Changes |
Impact |
| v0.11.0.2-g6e46593e-aliyun |
registry.cn-hangzhou.aliyuncs.com/acs/flannel:v0.11.0.2-g6e46593e-aliyun |
August 2, 2019 |
Fixed source IP address loss after Flannel upgrades. |
No impact on workloads. If a container name conflict causes the upgrade to fail, see Troubleshoot add-on errors. |