CI: pasta is failing since late February 2026

[AkihiroSuda]

CI was green as of the release of v3.0.0-alpha.2 (Feb 9): https://github.com/rootless-containers/rootlesskit/commits/master/

However, pasta tests began to fail on Fen 27, although no code was updated in our repo:
https://github.com/rootless-containers/rootlesskit/actions/runs/22454087825/job/65030495644

[INFO] [benchmark:iperf3::port] implicit --net=pasta --mtu=65520
+ grep -q -- --detach-netns
+ rkpid=14
+ sleep 3
+ rootlesskit --net=pasta --mtu=65520 --port-driver=implicit --state-dir=/tmp/tmp.GmiNsAZpkw iperf3 -s
time="2026-02-26T17:59:54Z" level=warning msg="[rootlesskit:parent] specifying --disable-host-loopback is highly recommended to prohibit connecting to 127.0.0.1:* on the host namespace (requires pasta, slirp4netns, or VPNKit)"
time="2026-02-26T17:59:54Z" level=warning msg="[rootlesskit:parent] \"pasta\" network driver is experimental. Needs very recent version of pasta (see docs/network.md)."
time="2026-02-26T17:59:54Z" level=warning msg="[rootlesskit:child ] failed to mount sysfs, falling back to read-only mount: operation not permitted"
time="2026-02-26T17:59:54Z" level=warning msg="[rootlesskit:child ] failed to mount sysfs: operation not permitted"
time="2026-02-26T17:59:54Z" level=warning msg="[rootlesskit:child ] Mounting /etc/resolv.conf without copying-up /etc. Note that /etc/resolv.conf in the namespace will be unmounted when it is recreated on the host. Unless /etc/resolv.conf is statically configured, copying-up /etc is highly recommended. Please refer to RootlessKit documentation for further information."
+ rootlessctl='rootlessctl --socket=/tmp/tmp.GmiNsAZpkw/api.sock'
+ '[' implicit '!=' implicit ']'
+ iperf3 -t 30 -c 127.0.0.1
iperf3: error - unable to connect to server - server may have stopped running or use a different port, firewall issue, etc.: Connection refused
Error: Process completed with exit code 1.

The versions of the dependencies such as pasta are pinned in Dockerfile:

rootlesskit/Dockerfile

Lines 1 to 8 in a313ce8

	ARG GO_VERSION=1.24
	ARG UBUNTU_VERSION=24.04
	ARG SHADOW_VERSION=4.17.4
	ARG SLIRP4NETNS_VERSION=v1.3.2
	ARG VPNKIT_VERSION=0.6.0
	ARG PASST_VERSION=2025_04_15.2340bbf
	ARG DOCKER_VERSION=28.1.1
	ARG DOCKER_CHANNEL=stable

The failure might be related to the update of the GitHub Actions runner:

• Old: https://github.com/actions/runner-images/blob/ubuntu24/20260201.15/images/ubuntu/Ubuntu2404-Readme.md
  • Kernel Version: 6.11.0-1018-azure
• New: https://github.com/actions/runner-images/blob/ubuntu24/20260224.36/images/ubuntu/Ubuntu2404-Readme.md
  • Kernel Version: 6.14.0-1017-azure