Error when trying to run kubeadm join

ztrubow

At step 15 on section 3.2 (grow the cluster), when i run the command I am getting this output:

I0822 00:13:09.532678 3997 join.go:408] [preflight] found NodeName empty; using OS hostname as NodeName
I0822 00:13:09.532841 3997 initconfiguration.go:116] detected and using CRI socket: unix:///var/run/containerd/containerd.sock
[preflight] Running pre-flight checks
I0822 00:13:09.532920 3997 preflight.go:93] [preflight] Running general checks
I0822 00:13:09.532968 3997 checks.go:280] validating the existence of file /etc/kubernetes/kubelet.conf
I0822 00:13:09.533009 3997 checks.go:280] validating the existence of file /etc/kubernetes/bootstrap-kubelet.conf
I0822 00:13:09.533029 3997 checks.go:104] validating the container runtime
I0822 00:13:09.564730 3997 checks.go:329] validating the contents of file /proc/sys/net/bridge/bridge-nf-call-iptables
I0822 00:13:09.564803 3997 checks.go:329] validating the contents of file /proc/sys/net/ipv4/ip_forward
I0822 00:13:09.564875 3997 checks.go:644] validating whether swap is enabled or not
I0822 00:13:09.564929 3997 checks.go:370] validating the presence of executable crictl
I0822 00:13:09.564957 3997 checks.go:370] validating the presence of executable conntrack
I0822 00:13:09.564985 3997 checks.go:370] validating the presence of executable ip
I0822 00:13:09.565008 3997 checks.go:370] validating the presence of executable iptables
I0822 00:13:09.565033 3997 checks.go:370] validating the presence of executable mount
I0822 00:13:09.565057 3997 checks.go:370] validating the presence of executable nsenter
I0822 00:13:09.565080 3997 checks.go:370] validating the presence of executable ebtables
I0822 00:13:09.565104 3997 checks.go:370] validating the presence of executable ethtool
I0822 00:13:09.565124 3997 checks.go:370] validating the presence of executable socat
I0822 00:13:09.565150 3997 checks.go:370] validating the presence of executable tc
I0822 00:13:09.565171 3997 checks.go:370] validating the presence of executable touch
I0822 00:13:09.565200 3997 checks.go:516] running all checks
I0822 00:13:09.578345 3997 checks.go:401] checking whether the given node name is valid and reachable using net.LookupHost
I0822 00:13:09.580331 3997 checks.go:610] validating kubelet version
I0822 00:13:09.639145 3997 checks.go:130] validating if the "kubelet" service is enabled and active
I0822 00:13:09.648974 3997 checks.go:203] validating availability of port 10250
I0822 00:13:09.649179 3997 checks.go:280] validating the existence of file /etc/kubernetes/pki/ca.crt
I0822 00:13:09.649205 3997 checks.go:430] validating if the connectivity type is via proxy or direct
[preflight] Some fatal errors occurred:
[ERROR FileContent--proc-sys-net-bridge-bridge-nf-call-iptables]: /proc/sys/net/bridge/bridge-nf-call-iptables does not exist
[ERROR FileContent--proc-sys-net-ipv4-ip_forward]: /proc/sys/net/ipv4/ip_forward contents are not set to 1
[preflight] If you know what you are doing, you can make a check non-fatal with --ignore-preflight-errors=...
error execution phase preflight

If anyone could offer some insight, i've tried a few things found googling but nothing has helped at the moment. Happy to provide any other commands needed

fazlur.khan

@ztrubow

Looks like you have a missed few pre-requisite steps. Execute the below steps and re-try to grow the cluster.

Ensure Kernel has modules

sudo modprobe overlay
sudo modprobe br_netfilter

Update networking to allow traffic

cat <<EOF | sudo tee /etc/sysctl.d/kubernetes.conf
net.bridge.bridge-nf-call-ip6tables = 1
net.bridge.bridge-nf-call-iptables = 1
net.ipv4.ip_forward = 1
EOF

sudo sysctl --system

Note: If you get port in use errors, reset and then retry. To reset run the command "kubeadm reset" on worker node.

xtrnror

This happens in GCP when you just add a key to authorized_keys rather adding your user via IAM. Or you may use "SSH" next to the compute engine.

chrispokorni

Hi @xtrnror,

Whether the user is added via IAM admin or simply through the auth key has no impact on the cluster init or join. This is the case for GCP, AWS, and other cloud providers. The error was pointing at missing configuration options that may have been missed from earlier steps.

Regards,
-Chris