Erlang Diameter Credit Control Server Application

This repository contains an example OTP DCCA application server built in Erlang.

To run the commands, you need rebar3 that can be either installed into the system (for example using Brew on Mac) or downloaded into the current application diretory (with execution permission).

To build the modules and diameter dictionaries, use rebar:

rebar3 compile

To start the module in a shell use:

rebar3 shell

Or use the provided Makefile:

make shell

To exit, type Ctrl+G to call the Erlang shell followed by the command "q".

The server also contains a flamegraph style tracer that can be called using dccaserver:trace(). from the console (Erlang shell) that will collect data for 10 seconds. There is also a dccaserver:trace(Integer). function that accepts the amount of collection time in seconds.

The tracer will generate a .out file that can be converted to an SVG file with cat flame-xxxxx.trace.out|grep -v lager | ./_build/default/lib/eflame/flamegraph.riak-color.pl > flame.svg (for example filtering-out lager calls) or opened on a flamegraph viewer website like https://www.speedscope.app/.

A release is also available and built with the commands below. To load the application use:

rebar3 release
./_build/default/rel/dccaserver/bin/dccaserver console

To create a release and a tar.gz archive for production with erts included:

rebar3 as prod release

./_build/prod/rel/dccaserver/bin/dccaserver console
rebar3 as prod tar

Monitoring and Running on Docker

The server exposes Prometheus metrics for the BEAM VM and the application at http://localhost:9000/metrics. There are some Grafana dashboards included that were sourced from https://github.com/deadtrickster/beam-dashboards.

Sample metrics:

# TYPE diameter_applications gauge
# HELP diameter_applications Number of installed DIAMETER applications.
diameter_applications{svc="dccaserver"} 1
# TYPE diameter_connections gauge
# HELP diameter_connections Number of connections to peers.
diameter_connections{svc="dccaserver",peer="example.com",type="responder",state="okay",protocol="tcp"} 1
# TYPE diameter_messages gauge
# HELP diameter_messages Number of requests.
diameter_messages{svc="dccaserver",peer="example.com",direction="recv",type="answer",msg="DWA",rc="2001"} 6
diameter_messages{svc="dccaserver",peer="example.com",direction="recv",type="request",msg="CCR"} 6
diameter_messages{svc="dccaserver",peer="example.com",direction="recv",type="request",msg="CER"} 1
diameter_messages{svc="dccaserver",peer="example.com",direction="recv",type="request",msg="DWR"} 3
diameter_messages{svc="dccaserver",peer="example.com",direction="send",type="answer",msg="CCA",rc="2001"} 6
diameter_messages{svc="dccaserver",peer="example.com",direction="send",type="answer",msg="CEA",rc="2001"} 1
diameter_messages{svc="dccaserver",peer="example.com",direction="send",type="answer",msg="DWA",rc="2001"} 3
diameter_messages{svc="dccaserver",peer="example.com",direction="send",type="request",msg="DWR"} 6
# TYPE diameter_errors gauge
# HELP diameter_errors Number of errors.

You can run the complete application stack with the DCCA server, Prometheus and Grafana on Docker containers with:

make stack

Prometheus will be accessible at http://localhost:9090/metrics and Grafana at http://localhost:3000. Login with "admin/admin" and load the dashboards from "Erlang/DCCA" folder.

Systemd service

For production deployments, if running on Systemd is preferred, build the application tar.gz, install to /opt/dccaserver and copy the systemd service file.

# Build application .tar.gz
make tar
# copy to target host
scp _build/prod/rel/dccaserver/dccaserver-1.0.0.tar.gz user@host:

# On target host
mkdir /opt/dccaserver
pushd /opt/dccaserver
tar vxf ~/dccaserver-1.0.0.tar.gz # point to correct path
popd
cp dccaserver.service /etc/systemd/system
systemctl daemon-reload
systemctl enable dccaserver # to enable start on boot
systemctl start dccaserver

Testing

To test the server, use the client module from project dcca-client-OTP or Seagull with included files.

Client (dcca-client-OTP)

If using the client sample application, clone the repository linked above and inside it run:

git clone https://github.com/carlosedp/dcca-client-OTP
cd dcca-client-OTP
make shell
dccaclient:test().

Seagull

Seagull can be used to generate Diameter traffic to the server. The configuration, scenario xml and start scripts are in test/seagull dir.

Test can be run with make seagull that will use Docker with the application and the test configs provided here. Before running, adjust the server IP in the conf_GPRS.xml file if needed (currently calls hostname dccaserver that is passed thru Docker).

The Docker image was built from https://github.com/carlosedp/Seagull.

Also the application can be installed from http://gull.sourceforge.net/doc/.