How to create /run/flannel/subnet.env at Node boot

Hello,

At reboot, I always have all my pods Evicted, and just manually creating /run/flannel/subnet.env with the following content brings them Runing :

FLANNEL_NETWORK=10.244.0.0/16
FLANNEL_SUBNET=10.244.0.1/24
FLANNEL_MTU=1450
FLANNEL_IPMASQ=true

How to make that /run/flannel/subnet.env persistent over reboots?

Kubernetes version:

# kubectl version
Client Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.4", GitCommit:"e6c093d87ea4cbb530a7b2ae91e54c0842d8308a", GitTreeState:"clean", BuildDate:"2022-02-16T12:38:05Z", GoVersion:"go1.17.7", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"23", GitVersion:"v1.23.5", GitCommit:"c285e781331a3785a7f436042c65c5641ce8a9e9", GitTreeState:"clean", BuildDate:"2022-03-16T15:52:18Z", GoVersion:"go1.17.8", Compiler:"gc", Platform:"linux/amd64"}

Cloud being used: bare-metal
Host OS: Linux CentOS7