Environment variables in configuration files

[preinhardt]

Hi,

it is possible to use linux environment variables in the configuration files?

The backround is, that I want to use the "HOSTNAME" in the configuration files.

Update:
In the configuration files I mean in detail the *.cfg files in services.
If that does not work, where would I have to insert this as an enhancement in the code (Unix/Windows).

Would this be accepted as a pull request?

[triller-telekom]

Currently it is not supported to insert environment variables into those .cfg files. The (ConfigDispatcher)[https://github.com/eclipse/smarthome/blob/master/bundles/config/org.eclipse.smarthome.config.dispatch/src/main/java/org/eclipse/smarthome/config/dispatch/internal/ConfigDispatcher.java] is responsible for parsing these files.

Before you create a PR: May I ask what you are trying to achieve by inserting the HOSTNAME environment variable into the config file? I.e. what is your specific use case that you are trying to cover?

[preinhardt]

I have posted my specific use case in the openHAB community chat forum.

https://community.openhab.org/t/additional-parameter-in-mqtt-persistence/36039

[triller-telekom]

From the posted link I read that you are trying to send MQTT messages that have the HOSTNAME in their topic from openHAB/ESH to a MQTT broker, right?

So I am wondering if configuration files are the right place to touch here. You somehow need access to the hostname where openHAB/ESH is running on.

So where do you create your messages with your custom topic? Within rules? Then maybe you need to have a way to retrieve the HOSTNAME from within a rule in the ruleengine?

[philomatic]

@triller-telekom You can define the custom mqtt topic to publish to via the mqtt.persist file:

http://docs.openhab.org/addons/persistence/mqtt/readme.html

Apart from this use-case:
I can imagine that using unix (and windows) environment variables in the .cfg / .persist files could come in handy, not only for MQTT ?

I'm thinking about system hostname for callbacks (is there (apart from java code) any other chance in ESH / OH2 to retrieve the system hostname?), locales and time zones, pwd.

[triller-telekom]

I'm thinking about system hostname for callbacks (is there (apart from java code) any other chance in ESH / OH2 to retrieve the system hostname?), locales and time zones, pwd.

That's why I want to know where he needs access to the hostname. Because things such as timezone and locale can be retrieved via I18nProvider. So I could imagine that the hostname can also be retrieved, maybe via the NetworkAddressService