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davesteele / comitup

Bootstrap Wifi support over Wifi
https://davesteele.github.io/comitup/
GNU General Public License v2.0
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Q: what systemd to depend upon? #118

Closed marcelstoer closed 4 years ago

marcelstoer commented 4 years ago

This is related to #116. Still working on dumping (network) information onto a display on startup as part of the application init sequence.

I had created a systemd service wrapping the Python code like so:

[Unit]
After=multi-user.target
...
[Install]
WantedBy=multi-user.target

It turned out that multi-user.target really isn't the right service to depend upon as my service wouldn't start when comitup was in AP mode.

Which service do you suggest I depend upon so that my service starts after the comitup/NetworkManager initialization but regardless of whether the device is in client or AP mode? This should reduce the risk of my app running too early and then report it be not connected to the internet (I'm polling the comitup D-Bus state).

davesteele commented 4 years ago

This doesn't really have anything to do with Comitup. Look at systemd resrouces.

muelli commented 4 years ago

this may be a silly as it seems trivial, but have you tried comitup.service?

marcelstoer commented 4 years ago

This doesn't really have anything to do with Comitup.

Apart from the fact that I'm working on a comitup image, no, that's true 😉 I thought you might have a hint based on your knowledge of which services comitup depends upon.

have you tried comitup.service

I had thought about it but not tried. I have since learned about systemd-analyze plot > plot.svg (see below) and that's really helpful.

So, starting after comitup.service is too early - at least for cases when the configured WiFi is available. My service (green) would start and detect that the connection to the AP hasn't been established yet. systemd-analyze-comitup service

Instead, starting after DHCP is just about right. systemd-analyze-dhcpcd service

However, when no configured WiFi is available and comitup is in HOTSPOT mode my service does not start as the DHCP service is not started either - I guess. Remember I'm a bit blind here as I can't SSH into the Pi at this point and don't have a Micro-HDMI connector to see any output.