Fly transmogrifies runc
containers into Firecracker VMs supervised by its own init
which in addition to other things is fussy at letting any other process read from stdout
.
root
is the safest bet to have everything running smoothly, apparently, even if it needn’t be the case.
The specific issue you’re seeing has been discussed a number of times on this very forum. Here’s a recent discussion: Allow non-root users to write to stdout/stderr - #13 by ignoramous
As you (and others) found out Dockerfiles on Fly aren’t the same as Dockerfiles everywhere else. For Fly, Dockerfiles are a convinient way to hook into the existing ecosystem: Early look: "fly launch" That said, it works almost all of the time, until it doesn’t.