fix(kubernetes): match DinD bridge MTU to the pod network #50

Merged

rcsheets merged 2 commits from fix/dind-mtu-match-pod-network into main

2026-07-20 00:12:25 +00:00

rcsheets commented

2026-07-19 23:46:15 +00:00

Owner

Also bring in a doc update

rcsheets added 2 commits

2026-07-19 23:46:15 +00:00

fix(kubernetes): match DinD bridge MTU to the pod network 9f9615400c

Privileged (DinD) pools ran dockerd with the default bridge MTU of 1500.
On overlay CNIs the pod interface is smaller (e.g. 1450 with VXLAN
encapsulation), so job containers emitted oversized frames that silently
stalled large transfers: `apt-get update` and image pulls crawled or
failed, flooding logs with apt's "Tried to start delayed item ... but
failed". Reproduced in a runner's dind: a 9.6 MB Packages fetch Ign'd and
retried at 304 kB/s.

The DinD sidecar now wraps dockerd-entrypoint.sh to read the pod's eth0
MTU (shared netns) and start dockerd with a matching --mtu, so docker0 and
every nested job container match the pod network. Verified end-to-end:
docker0 drops to 1450 and the same apt fetch completes in 1s at 7.3 MB/s
with no retries.

Adds spec.backend.kubernetes.dockerMTU to override the auto-detected value
for paths whose effective MTU is smaller than the pod interface (a further
tunnel the operator can't observe) or when eth0 is the wrong interface.
Applies to every privileged pool once the image rolls out; no pool changes
required.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs: forbid touching CHANGELOG.md unless the user asks

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bd1ff776e0

Strengthen the existing directive: do not modify CHANGELOG.md at all
unless the user explicitly requests it, and never as a side effect of
another change.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

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2026-07-19 23:46:16 +00:00

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rcsheets merged commit f84bc09e05 into main

2026-07-20 00:12:25 +00:00

rcsheets deleted branch fix/dind-mtu-match-pod-network

2026-07-20 00:12:26 +00:00

rcsheets referenced this pull request from a commit

2026-07-20 00:12:27 +00:00

Merge pull request 'fix(kubernetes): match DinD bridge MTU to the pod network' (#50) from fix/dind-mtu-match-pod-network into main