Linking Apps Internally
You’ll often need to connect individual apps to each other to exchange data, for example: Sonarr to SABnzbd to allow Sonarr to control downloads within SABnzbd.
The backend for TrueNAS SCALE Apps is Kubernetes. As you can’t point directly to other Kubernetes app containers using their IP address you need to use their internal domain name instead.
Please beware: this name is only available between Apps and cannot be reached from the host/node or your own PC.
Main service
For most apps, you’ll want to contact the main service (usually the web interface or primary way you interact with the app)
Please replace $NAME with the name you gave your App when installing it, and $APP with the name the app has on the catalog as needed.
If your app name contains the name of the app as in the catalog, the format is as follows.
$NAME.ix-$NAME.svc.cluster.local
If your app name does NOT contain the name of the app as in the catalog, the format is as follows.
$NAME-$APP.ix-$NAME.svc.cluster.local
Multiple Services
If you need to reach a different service of your app (which is not often the case), you need a slightly different format.
As well as the above naming, replace $SVCNAME with the name of the service you want to reach:
If your app name contains the name of the app as in the catalog, the format is as follows.
$NAME-$SVCNAME.ix-$NAME.svc.cluster.local
If your app name does NOT contain the name of the app as in the catalog, the format is as follows.
$NAME-$APPNAME-$SVCNAME.ix-$NAME.svc.cluster.local
Be aware: you’ll only be able to reach ports published on the service they are published to - see the Multiple Services example below for a demonstration of this.
List Internal Domain Names using HeavyScript
HeavyScript is a very useful command-line utility built to help simplify administration of TrueNAS Scale apps. One of it’s many features is being able to list the internal DNS names and ports of your apps. If you are unsure of how names are “built” - then this is by far the easist and recommended way to be sure you are using the correct name.
Firstly, install HeavyScript or update your current installation to at least version 2.9.0. Visit their GitHub repo to find out how: https://github.com/Heavybullets8/heavy_script
To list the DNS entries for your apps, open the TrueNAS Scale shell and use the command heavyscript dns or heavyscript dns APPNAME1 APPNAME2
Naming Examples
Main Service
To reach an app named “sabnzbd” (note: the name contains the catalog app name “sabnzbd”) you can use the following internal domain name:
sabnzbd.ix-sabnzbd.svc.cluster.local
To reach an app named “sab” (note: the name does NOT contain catalog app name “sabnzbd”) you can use the following internal domain name:
sab-sabnzbd.ix-sab.svc.cluster.local
To reach an app named “sabnzbd-23” (note: the name contains the catalogue app name “sabnzbd” as well as extra name information “-23”) you can use the following internal domain name:
sabnzbd-23.ix-sabnzbd-23.svc.cluster.local
Multiple Services
This is an example of where an app has more than one service, in this case it’s Traefik
It’s main service (note it follows the examples above)
traefik.ix-traefik.svc.cluster.local
Then, it’s extra services - one for metrics, and one for tcp
traefik-metrics.ix-traefik.svc.cluster.localtraefik-tcp.ix-traefik.svc.cluster.local
When you install an app with multiple services, you’ll be able to see which ports are published to which service - if you aren’t sure of this from the installation/edit view then HeavyScript will also show these.
This is a HeavyScript output for Traefik, showing it’s services and the published ports
traefik.ix-traefik.svc.cluster.local 9000/TCPtraefik-metrics.ix-traefik.svc.cluster.local 9180/TCPtraefik-tcp.ix-traefik.svc.cluster.local 80/TCP,443/TCP
So, if you wanted to reach the metrics port, you should use traefik-metrics.ix-traefik.svc.cluster.local as the name as that port would not be available on other services.