[systemd-devel] networking services management idea

[Chris Ferron]

On 08/01/2012 11:57 PM, David Strauss wrote:
> Unless the services take long to start, you'll have a much better time
> with socket activation. With socket activation, the service won't just
> wait until network availability to come online; the service will wait
> until an actual request to come online.
>
> Also check out my other posts to the mailing list about network
> availability levels and service management.
Thanks David, I just read you posts in the thread " network consuming 
user services" where some of this was touched on. I see the points on 
the services being socket activated or listing to netlink and so-forth. 
But in my case, there are outgoing services, so protocol specific, that 
one just might not want even started unless a specific state is 
obtained. Agreed that network session level activity should be monitored 
and managed within the service, but before that when to really start the 
service.
I am not talking about stalling or interfering with network.target, but 
I suggest is setting up targets that outgoing services could use or 
distro/admins could use to better structure in a generic scene.

For instance. There is a service that uses NFC to used in credit card 
services. lets call it NFC-your-money.service
This service needs an an active NFC connection, and is the service used 
to pay for things using you phone from you checking account. (No I don't 
have or use this.)

1. I don't want such a service running if I don't have a NFC connection.
2. I don't want it running if I loose my NFC connection.
3. I don't want to start the service to check if I have a NFC connection .

I hope that having some predefined targets like maybe

network-ready.target
         --->network-ready.target.wants
                     ---> local-only-network.service
network-online.target
         ---> network-online.target.wants
                     ---> npt.service
                     ---> device-updater.service
network-nfc-ready.target
         ---> network-nfc-ready.target.wants
                     ---> NFC-your-money.service


Then mapping out some singles to network managers and associating 
networking service state with targets
we could start and stop the units based on the change in networking 
state. Then depending on the state, using systemd start or stop unit 
method we can start and stop the targets.

Again the thinking is using this only for services were is appropriate. 
Mostly by the digression of the distros, service providers, or device 
customizations, or even admins.

-Chris