ExaBGP¶

If installing ExaCheck from PyPi or source, ExaBGP requires some additional setup steps. If you are deploying the Docker container there is no need to follow the below steps.

System User¶

A user account should be added for ExaBGP so it does not run as root. To add the account:

useradd -Ms /usr/sbin/nologin -d /run/exabgp exabgp

systemd Service File¶

Installing ExaBGP from source or pip does not include a systemd service file. Create the file /etc/systemd/system/exabgp.service with this content:

[Unit]
Description=ExaBGP
Documentation=man:exabgp(1)
Documentation=man:exabgp.conf(5)
Documentation=https://github.com/Exa-Networks/exabgp/wiki
After=network.target
ConditionPathExists=/etc/exabgp/exabgp.conf

[Service]
Environment=exabgp_daemon_daemonize=false
User=exabgp
Group=exabgp
RuntimeDirectory=exabgp
RuntimeDirectoryMode=0750
ExecStartPre=-/usr/bin/mkfifo /run/exabgp/exabgp.in
ExecStartPre=-/usr/bin/mkfifo /run/exabgp/exabgp.out
ExecStart=/opt/exacheck/bin/exabgp server /etc/exabgp/exabgp.conf
ExecReload=/bin/kill -USR1 $MAINPID
Restart=always
CapabilityBoundingSet=CAP_NET_ADMIN
AmbientCapabilities=CAP_NET_ADMIN

[Install]
WantedBy=multi-user.target

Once the service file is created the service can be enabled to start on boot:

systemctl enable exabgp.service

Configuration¶

ExaBGP needs to be configured to use ExaCheck. By default, the ExaBGP and ExaCheck configuration will be sourced from the /etc/exabgp directory; create that directory if it does not already exist:

mkdir /etc/exabgp

Environment File¶

The ExaBGP environment file needs to be created. To generate a default environment file run the following command:

/opt/exacheck/bin/exabgp --fi > /etc/exabgp/exabgp.env

The following configuration options need to be changed in the environment file:

API ack set to false
ExaBGP user changed from nobody to exabgp

A sed one liner to change the required values can be executed:

sed -i \
    -e "s:ack = true:ack = false:" \
    -e "s:user = 'nobody':user = 'exabgp':" \
    /etc/exabgp/exabgp.env

Configuration File¶

The ExaBGP configuration file, /etc/exabgp/exabgp.conf, then needs to be created. An example template:

# Define the ExaCheck process
process exacheck {
    run exacheck run;
    encoder text;
}

# Connect to the BGP neighbor 192.0.2.1
neighbor 192.0.2.1 {
    description "Example BGP neighbor";

    # This should be set to the ExaBGP router ID (eg. the main IP address of this server)
    router-id 192.0.2.10;

    # The local address to source BGP connections from
    local-address 192.0.2.10;

    # The local and peer AS numbers
    local-as 65515;
    peer-as 65515;

    # The address family to advertise
    family {
        ipv4 unicast;
    }

    # Allow routes sent from the ExaCheck process to be sent to this neighbor
    api {
        processes [ exacheck ];
    }
}

For more configuration examples, see the ExaCheck configuration examples page.

Once ExaBGP and ExaCheck have been configured, the systemd service can then be started:

systemctl start exabgp.service