fix(master): refuse tmpfs options Swarm cannot express - #65
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The Swarm backend translated a docker-run tmpfs spec by keeping size= and discarding everything else. The own_runner job container installs the miner agent into /tmp/.local under a read-only rootfs, so its spec carries exec; tmpfs is noexec unless told otherwise. Routing that workload through Swarm therefore produced a noexec /tmp, where the agent loads no shared object and fails with "failed to map segment from shared object" -- a symptom that took hours to trace back to a dropped mount flag. Swarm cannot express the flag at all: against Docker 29.2.1 a bare exec is rejected as a non key=value field and tmpfs-options is an unknown option, so only tmpfs-size and tmpfs-mode survive. Translate those two, accept the flags Swarm already applies by default, and refuse anything else -- exec loudest of all -- rather than dropping it and failing far from the cause.
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Why
The Swarm backend translated a docker-run tmpfs spec by keeping
size=and discarding every other option.The own_runner job container installs the miner agent into
/tmp/.localunder a read-only rootfs, so its spec is/tmp:rw,nosuid,exec,size=2g. tmpfs isnoexecunless told otherwise. Routing that workload through Swarm produced a noexec /tmp, where the agent loads no shared object and dies withfailed to map segment from shared object— the same symptom that already cost hours to trace on the broker path (fixed in #64).The broker path is what production runs today, so this was latent, not live. It becomes live the moment the Swarm path is enabled.
What
Swarm cannot express the flag at all. Verified against Docker 29.2.1 on the prod host:
type=tmpfs,...,execinvalid field 'exec' must be a key=value pairtype=tmpfs,...,tmpfs-options=execunknown option 'tmpfs-options'type=tmpfs,destination=/tmp,tmpfs-size=1048576So translation is impossible and silence is the worst option. This change:
size=andmode=totmpfs-size/tmpfs-mode;rw,noexec,nosuid,nodev);exec, and refuses any other untranslatable option, instead of dropping it.Tests
New
tests/unit/test_swarm_tmpfs_exec.py, written failing first: the two refusal tests failed withDID NOT RAISEbefore the change while the three translation tests already passed, pinning that existing specs keep working. 5 passed after.