gte-dameon doc

doc/daemon.adoc

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+= Long running daemon
+2022-09-26
+
+There are two scripts that need to be executed on a regular basis:
+
+* Processing newly arrived emails
+* Generating new instances of recurring tasks
+
+This can be done by the cli app, but that requires a manual action. Generating new instances of recurring tasks should happen only once a day, but the processing of new emails is ideally done as often as every couple of minutes. One can use a cron job to do this, but that requires a machine that is switched on for the majority of the day, at least during waking hours. to make sure changes are reflected. At that point we might as well have a real service, with proper logging, etc. The `gte-daemon` is just that. The cli can still be used as a fallback though.
+
+In the past it has run as a systemd service, but now there is a simple Docker container for portability between hosting providers. See `Dockerfile.daemon` in the repository. It is a simple service and does not require much.
+
+== Parameters and configuration
+
+The Dockerfile is configured with the following environment variables:
+
+* `IMAP_URL` IMAP hostname including port number, for instance: `imap.example.com:993`
+* `IMAP_USER`
+* `IMAP_PASSWORD`
+* `IMAP_FOLDER_PREFIX` To be used if combined with a normal email account, see https://ewintr.nl/gte/basic-flow/[basic flow], for instance `GTE/`
+
+* `SMTP_URL` SMTP hostname, including port number, for instance: `smtp.example.com:465`
+* `SMTP_USER`
+* `SMTP_PASSWORD`
+
+* `GTE_TO_NAME` Name of recipient when sending mails for tasks, for instance `gte`
+* `GTE_TO_ADDRESS` Address of recipient when sending mails for tasks, for instance: `gte@example.com`
+* `GTE_FROM_NAME` Name of sender when sending mails for tasks, fot instance: `gte`
+* `GTE_FROM_ADDRESS` Address of recipient when sending mails for tasks, for instance: `gte@example.com`
+* `GTE_DAYS_AHEAD` Number of days in the future for which recurring tasks must be instantiated, for example: `6` 
+