16. APNs Relay Manual#
taler-apns-relay is an Apple Push Notification relay. It send a background notification to registered devices at a regula interval to wakup an application and enable recurrent background sync.
This manual targets system administrators who want to install and operate an APNs relay.
16.1. Installation#
16.1.1. Installing on Debian#
To install the GNU Taler Debian packages, first ensure that you have the right Debian distribution. At this time, the packages are built for Debian trixie.
You need to add a file to import the GNU Taler packages. Typically,
this is done by adding a file /etc/apt/sources.list.d/taler.list that
looks like this:
deb [signed-by=/etc/apt/keyrings/taler-systems.gpg] https://deb.taler.net/apt/debian trixie main
Next, you must import the Taler Systems SA public package signing key into your keyring and update the package lists:
# wget -O /etc/apt/keyrings/taler-systems.gpg \
https://taler.net/taler-systems.gpg
# apt update
Note
You may want to verify the correctness of the Taler Systems SA key out-of-band.
Now your system is ready to install the official GNU Taler binary packages using apt.
To install the adapter, you can now simply run:
# apt install taler-apns-relay
16.1.2. Installing on Ubuntu#
To install the GNU Taler Ubuntu packages, first ensure that you have
the right Ubuntu distribution. At this time, the packages are built for
Ubuntu Lunar and Ubuntu Jammy. Make sure to have universe in your
/etc/apt/sources.list.d/ubuntu.sources (after main)
as we depend on some packages from Ubuntu universe.
A typical /etc/apt/sources.list.d/taler.list file for this setup
would look like this for Ubuntu Noble:
deb [signed-by=/etc/apt/keyrings/taler-systems.gpg] https://deb.taler.net/apt/ubuntu/ noble main
Next, you must import the Taler Systems SA public package signing key into your keyring and update the package lists:
# wget -O /etc/apt/keyrings/taler-systems.gpg \
https://taler.net/taler-systems.gpg
# apt update
Note
You may want to verify the correctness of the Taler Systems key out-of-band.
Now your system is ready to install the official GNU Taler binary packages using apt.
To install the adapter, you can now simply run:
# apt install taler-apns-relay
16.1.3. Building from source#
APNs Relay belongs to the Taler Rust project, and can be downloaded via Git:
$ git clone git://git.taler.net/taler-rust
$ cd taler-rust
You will need the latest version of the rust stable toolchain and a C toolchain:
$ sudo apt install rustup build-essential
$ rustup toolchain install stable
Then from top-level run:
$ ./bootstrap
To install the adapter as a Debian/Ubuntu package with an automated secure setup and systemd services:
$ sudo apt install debhelper
$ make deb
$ sudo dpkg -i ../taler-apns-relay*.deb
If the previous steps succeeded, the taler-apns-relay command should be found in the $PATH.
16.1.4. Services, users, groups and file system hierarchy#
The taler-apns-relay package will create several system users to compartmentalize different parts of the system:
taler-apns-relay-httpd: runs the HTTP daemon with the API logic.taler-apns-relay-worker: runs the worker daemon interacting with the APNs API.postgres: runs the PostgreSQL database (from postgresql package).
The adapter setup uses the following system groups:
taler-apns-relay-db: group for all adapter users with direct database access, specifically taler-apns-relay-httpd and taler-apns-relay-worker.
The package will deploy systemd service files in
/usr/lib/systemd/system/ for the various components:
taler-apns-relay-httpd.service: registration REST API.taler-apns-relay-httpd.socket: systemd socket activation for the HTTP daemon.taler-apns-relay-worker.service: worker deamon interacting with the APNs API.taler-apns-relay.target: main target for the relay to be operational.
The deployment creates the following key locations in the system:
/etc/taler-apns-relay/: configuration files./run/taler-apns-relay/: contains the UNIX domain sockets for inter-process communication (IPC).
16.2. Configuration Fundamentals#
This chapter provides fundamental details about the adapter configuration.
The configuration for all adapter components uses a single configuration file
as entry point: /etc/taler-apns-relay/taler-apns-relay.conf.
System defaults are automatically loaded from files in
/usr/share/taler-apns-relay/config.d.
These default files should never be modified.
The default configuration taler-apns-relay.conf configuration file
also includes all configuration files in /etc/taler-apns-relay/conf.d.
The settings from files in
conf.d are only relevant to particular components of an adapter, while
taler-apns-relay.conf contains settings that affect all adapter components.
The directory /etc/taler-apns-relay/secrets contains configuration file snippets with
values that should only be readable to certain users. They are included with the @inline-secret@
directive and should end with .secret.conf.
To view the entire configuration annotated with the source of each configuration option, you
can use the taler-apns-relay config helper:
# taler-apns-relay config dump --diagnostics
16.3. Basic Setup#
16.3.1. Database setup#
The configuration file must include a connection string that tells the adapter how it should connect to the database. The default is:
[apns-relaydb-postgres]
config = postgres:///taler-apns-relay
If the database is run on a different host, please follow the instructions from the PostgreSQL manual for configuring remote access.
Assuming the configuration is correct, the following command initializes (or upgrades) the database schema using: You can then use a script to automate a secure database setup:
# taler-apns-relay-dbconfig
16.3.2. Worker setup#
You will need an Apple private key. Update the configuration files:
[apns-relay-worker]
KEY_ID = 555CFX5XXX
TEAM_ID = GDDDQ9418X
BUNDLE_ID = com.taler-systems.talerwallet
Copy the private key .p8 file to the configured path KEY_FILE (/var/lib/taler-apns-relay/key.p8 with the default config).
Make sure this file is accessible to the user running taler-apns-relay-worker, for the default services you should run:
$ chown taler-apns-relay-worker:taler-apns-relay-worker /var/lib/taler-apns-relay/key.p8
And then run the setup process:
$ sudo -u taler-apns-relay-worker taler-apns-relay -c /etc/taler-apns-relay/taler-apns-relay.conf setup
16.4. Deployment#
This chapter describes how to deploy the adapter once the basic installation and configuration are completed.
16.4.1. Reverse Proxy Setup#
By default, the taler-apns-relay-httpd service listens for HTTP connections
on a UNIX domain socket. To make the service publicly available, a reverse
proxy such as nginx should be used. We strongly recommend to configure nginx
to use TLS.
The taler-apns-relay package ships with a sample configuration that can be
enabled in nginx:
# vim /etc/nginx/sites-available/taler-apns-relay
< ... customize configuration ... >
# ln -s /etc/nginx/sites-available/taler-apns-relay /etc/nginx/sites-enabled/taler-apns-relay
# systemctl reload nginx
With this last step, we are finally ready to launch the main adapter process.
16.4.2. Launching the relay#
# systemctl enable --now taler-apns-relay.target