[inetknght]

    cp ./app.AppImage /srv/app/app.AppImage
    for deployment_host in $( <deployment_hosts jq '.[].hostname');
        ssh deployment_user@deployment_host /srv/app/app.AppImage &
    done

okay boss, what's the next problem?

[jrockway]

app.AppImage used up all the RAM on the machine, and the kernel OOMkilled sshd. Now it's time to roll back.

(But I guess it wasn't the fault of that deployment -- you just staged the binary, you didn't start it running.)

[inetknght]

The app.AppImage is staged to the network share and started on the remote host. The AppImage might eat all the RAM and the AppImage will get OOMkilled but sshd is unlikely to be killed. When the AppImage gets OOMkilled, the ssh session will end with an error and the ssh client will report that the session terminated unexpectedly.

I've done it (and later cringed). But it definitely works.