We recently hit the issue that `osbuild` crashed with:
```
Unable to decode response body "Traceback (most recent call last):
File \"/usr/bin/osbuild\", line 33, in <module>
sys.exit(load_entry_point('osbuild==124', 'console_scripts', 'osbuild')())
File \"/usr/lib/python3.9/site-packages/osbuild/main_cli.py\", line 181, in osbuild_cli
r = manifest.build(
File \"/usr/lib/python3.9/site-packages/osbuild/pipeline.py\", line 477, in build
res = pl.run(store, monitor, libdir, debug_break, stage_timeout)
File \"/usr/lib/python3.9/site-packages/osbuild/pipeline.py\", line 376, in run
results = self.build_stages(store,
File \"/usr/lib/python3.9/site-packages/osbuild/pipeline.py\", line 348, in build_stages
r = stage.run(tree,
File \"/usr/lib/python3.9/site-packages/osbuild/pipeline.py\", line 213, in run
data = ipmgr.map(ip, store)
File \"/usr/lib/python3.9/site-packages/osbuild/inputs.py\", line 94, in map
reply, _ = client.call_with_fds(\"map\", {}, fds)
File \"/usr/lib/python3.9/site-packages/osbuild/host.py\", line 373, in call_with_fds
kind, data = self.protocol.decode_message(ret)
File \"/usr/lib/python3.9/site-packages/osbuild/host.py\", line 83, in decode_message
raise ProtocolError(\"message empty\")
osbuild.host.ProtocolError: message empty
cannot run osbuild: exit status 1" into osbuild result: invalid character 'T' looking for beginning of value
...
input/packages (org.osbuild.files): Traceback (most recent call last):
input/packages (org.osbuild.files): File "/usr/lib/osbuild/inputs/org.osbuild.files", line 226, in <module>
input/packages (org.osbuild.files): main()
input/packages (org.osbuild.files): File "/usr/lib/osbuild/inputs/org.osbuild.files", line 222, in main
input/packages (org.osbuild.files): service.main()
input/packages (org.osbuild.files): File "/usr/lib/python3.11/site-packages/osbuild/host.py", line 250, in main
input/packages (org.osbuild.files): self.serve()
input/packages (org.osbuild.files): File "/usr/lib/python3.11/site-packages/osbuild/host.py", line 284, in serve
input/packages (org.osbuild.files): self.sock.send(reply, fds=reply_fds)
input/packages (org.osbuild.files): File "/usr/lib/python3.11/site-packages/osbuild/util/jsoncomm.py", line 407, in send
input/packages (org.osbuild.files): n = self._socket.sendmsg([serialized], cmsg, 0)
input/packages (org.osbuild.files): ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
input/packages (org.osbuild.files): OSError: [Errno 90] Message too long
```
The underlying issue is that the reply of the `map()` call is too
big for the buffer that `jsoncomm` uses. This problem existed before
for the args of map and was fixed by introducing a temporary file
in https://github.com/osbuild/osbuild/pull/1331 (and similarly
before in https://github.com/osbuild/osbuild/pull/824).
This commit writes the return values also into a file. This should
fix the crash above and make the function more symetrical as well.
Alternative/complementary version of
https://github.com/osbuild/osbuild/pull/1833
Closes: HMS-4537
88c35ea306