Unfortunately I have not had time to maintain this release, so it may not work reliably anymore (if installation trough HACS does not work try manually). There is now an official integration that provides the same functions and much more. The only thing you can do more with my app is to disable the monitoring through home assistant (manually or via an automation).

Using HACS, to install and track updates, is reccomended.

Alternatively, you can download all the files inside the apps directory to your local apps directory, then add the configuration to enable the nethassmo module.

This app listen to (user-defined) person entities (and consequently to the associated device tracker) and set Home or Away the corresponding person in Netatmo Welcome camera. This is usefull if you don't want to share device location with Netatmo and stick to Home Assistant device tracking.

Whit this app you can also activate/deactivate the camera monitoring using a switch in Home Assistant. This option it's called "GuestMode" cause it's particularly usefull when you have guests at home to avoid dozens of notification of unknown faces.

To use this app you need an Access Token from Netatmo.
Browse to https://dev.netatmo.com and login with your account or create one. Create a new app, give it a name and a description.
You have to fill data protection officer name and data protection officer email fields in order to move on (you can simply put your name and email here).
When you click on SAVE you obtain a client id and a client secret code. Write them down or keep the page open.

Now you can add nethassmo configuration to your apps.yaml file.
Insert module and class as usual then, you can add your Netatmo credentials directly in the file or reference them from the secret.yaml file.
If you want to monitor persons you have to specify the Home Assistant person sensor the app should listen to. Then you can specify an entity (e.g. input_boolean) to control "Guest Mode".

nethassmo:
  module: nethassmo
  class: Nethassmo
  user: youremail@email.com
  pswd: yourpassword
  client: 4f3ed70814549fb7f98b5t72
  secret: D8NzNVhdLMcy0QeTsin3tCcjmu0HGfZme9hKoEXkR
  persons: ['person.john', 'person.jane', 'person.name_3']
  guest_mode_switch: input_boolean.guestmode

Save the file and restart Appdaemon if it's not reloading automatically.
The first time Nethassmo is executed it will use the credentials you have previously provided for requesting an access token, and your home and persons data from Netatmo. All the data will be then added to the file nethassmo.cfg in nethassmo app directory.

[TOKEN]
token : 6c7810f49ad10534d29b51e7|ff78959ebeee5fb611a4aba1a37588f5
refresh : 6c7810f49ad10534d29b51e7|fb1d195a5d58cfe6e61287c3a3bfc619

[HOME]
home_id : 6c7810f49ad10534d29b51e7

[PERSONS]
john : not6424b-29c3-4820-79n4-ec9573b68h27
jane : 7u3006cf-c756-4e7c-b44a-e3d7e98637f4
name_3 : xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx

[SENSORS]
; Edit value (if needed) with the correspondig name from [PERSONS] section
; e.g. ${PERSONS:name}
sensor_john : ${PERSONS:john}
sensor_jane : ${PERSONS:jane}
sensor_name_3 : ${PERSONS:name_3}

>>> IMPORTANT <<<
Pay attention at [SENSORS] section.
The key is based on the friendly name of the monitored person.name from Home Assistant (the one you have specified in apps.yaml).
The corresponding value is a reference to the value of [PERSONS] section. By default Nethassmo app assumes that persons' friendly names in Home Assistant and the ones from Netatmo Welcome camera are the same.
If that's not the case you have to manually change the value.

Taking as an example the configuration above, if in Netatmo Welcome camera the user John had been configured as Johnny but in Home Assistant the person sensor frindly name is John, the resulting default configuration would had been

[PERSONS]
johnny : not6424b-29c3-4820-79n4-ec9573b68h27
jane : 7u3006cf-c756-4e7c-b44a-e3d7e98637f4
name_3 : xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx

[SENSORS]
; Edit value (if needed) with the correspondig name from [PERSONS] section
; e.g. ${PERSONS:name}
sensor_john : ${PERSONS:john}
sensor_jane : ${PERSONS:jane}
sensor_name_3 : ${PERSONS:name_3}

So in this case you have to modify ${PERSONS:john} with ${PERSONS:johnny} for the app to work.

Please feel free to open any issues or feature requests!

Theoretically the app should work with multiple cameras but currently I can test it with the only one I have.
If you want you can help me to add a second one ;)