Github runner: fatal: failed to verify network settings [...] overlaps with other one

[thediveo]

My nerdctl-related unit tests fail with IP address pool overlapping when run on a Github runner, please also see details of failed job.

The GH runner version is 2.305.0, the OS is Ubuntu 22.0.4.2LTS.

My unit test fails while executing nerdctl run -d --name foo busybox /bin/sleep 120s.

The error message thrown by nerdctl is:

time="2023-06-22T08:42:42Z" level=fatal msg="failed to verify networking settings: failed to create default network: subnet 10.4.0.0/24 overlaps with other one on this address space"

nerdctl and CNI plugins are installed with this helper script:

#!/bin/bash

# Download aux tools (nerdctl, CNI plugins) required to run some of the Gostwire
# tests.
#
# On purpose, we're not going to install from often totally outdated or lacking
# distro repositories, but from the Github projects directly.

CNI_PLUGINS_VERSION=v1.3.0
NERDCTL_VERSION=v1.4.0

BINDIR=${BINDIR:-/usr/local/bin}
CNIBINDIR=${CNIBINDIR:-/opt/cni/bin}

ARCH=$(dpkg --print-architecture)
echo "downloading tools for architecture ${ARCH}"

WGET_PREX="/tmp/nerdctl-and-friends"
mkdir -p ${WGET_PREX}
wget -P ${WGET_PREX} --backups=1 https://github.com/containernetworking/plugins/releases/download/${CNI_PLUGINS_VERSION}/cni-plugins-linux-${ARCH}-${CNI_PLUGINS_VERSION}.tgz
wget -P ${WGET_PREX} --backups=1 https://github.com/containerd/nerdctl/releases/download/${NERDCTL_VERSION}/nerdctl-${NERDCTL_VERSION#v}-linux-${ARCH}.tar.gz

echo "installing CNI plugins into ${CNIBINDIR}"
mkdir -p ${CNIBINDIR}
sudo tar -x -v -z -f ${WGET_PREX}/cni-plugins-linux-${ARCH}-${CNI_PLUGINS_VERSION}.tgz -C ${CNIBINDIR}
echo "installing nerdctl into ${BINDIR}"
sudo tar -x -v -z -f ${WGET_PREX}/nerdctl-${NERDCTL_VERSION#v}-linux-${ARCH}.tar.gz -C ${BINDIR}

Any ideas as to why things go south in the Github runner VMs?

[thediveo]

Something appeared to me, so I tried this ... and it triggered the same error:

1. deleted the "bridge" default network using nerdctl network rm bridge
2. created a custom bridge network using nerdctl network create test
3. nerdctl run -it --rm busybox ... boom:

FATA[0003] failed to verify networking settings: failed to create default network: subnet 10.4.0.0/24 overlaps with other one on this address space

looks as if there is something hard-wired that shouldn't be.