app-os-monitor (0.5.2) not working on r-pi

[cgreenhalgh]

(r-pi 3b w alpine 3.10 docker 19.3.2 - also tried on alpine 3.8 docker 18.something)
standard databox 0.5.2, trying to run driver-os-monitor (seems ok) then app-os-monitor, doesn't get data. Reports errors:

app-os-monitor.1.w0vwtxmaxa4s@databox    | [getStats] called ....
app-os-monitor.1.w0vwtxmaxa4s@databox    | makeArbiterPostRequest /token Error::  Can't connect so server
app-os-monitor.1.w0vwtxmaxa4s@databox    | Error getting Max dataSourceFreememStructured Error getting Arbiter Token: 500: 
app-os-monitor.1.w0vwtxmaxa4s@databox    | makeArbiterPostRequest /token Error::  Can't connect so server
app-os-monitor.1.w0vwtxmaxa4s@databox    | Error getting Min dataSourceFreememStructured Error getting Arbiter Token: 500: 

in component environment, DATABOX_ARBITER_ENDPOINT=tcp://arbiter:4444
no apparent errors in core-network - app container can resolve arbiter and seems to be able to connect to arbiter ports 4444/4445. there's no sign from the arbiter that it ever gets a request from the app.

[cgreenhalgh]

I tried building from source and it didn't work, but it does seem to if I build from source with Dockerfile-arm64v8 runtime based updated from

FROM arm64v8/alpine

to

FROM arm64v8/alpine:3.8

Before, since alpine updated, it was probably picking up an incompatible zmq library.
Presumably the problem with the uploaded image was different, but who knows...