fix(network-manager): handle null IPAM.Config in _subnet_in_use#33
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fix(network-manager): handle null IPAM.Config in _subnet_in_use#33
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Some Docker networks (created without an address pool) have IPAM.Config
set to explicit null rather than omitted. `.get("Config", [])` returns
None in that case, blowing up the iteration with
'NoneType' object is not iterable
and leaving subnet-in-use detection broken — the mock would then
happily allocate a subnet that's already taken.
Switch to `.get("Config") or []` so the fallback kicks in for both
missing and null.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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Summary
Docker networks created without an address pool have `IPAM.Config` set
to explicit `null`. `.get("Config", [])` returns `None` in that case,
which blows up the subsequent iteration with `'NoneType' object is not
iterable` — the warning fires, `_subnet_in_use` returns `False` by
default, and the mock happily allocates an already-taken subnet.
Swap to `.get("Config") or []` so the fallback kicks in for both
`null` and `missing`.
How it was found
During local harness validation of the Madagascar seed flow. The mock
would warn `Failed to inspect existing Docker subnets: 'NoneType' object
is not iterable` after certain Docker states, and the next seed request
got an intermittent subnet-overlap.
Test plan
NoneType warning.
🤖 Generated with Claude Code