# Tango with systemd integration

Intended audience: administrators

This recipe shows how to set up Tango environment using systemd, for instance on a developer’s box

At first systemd units must be defined for common Tango device servers (db, tango-accesscontrol, tango-test etc):

    # /etc/systemd/system/tango-db.service
    [Unit]
    Description = Tango DB
    Requires=mysql.service
    After=mysql.service
    StopWhenUnneeded=true

    [Service]
    User=tango
    Environment=TANGO_HOST=localhost:10000
    ExecStart=/opt/tango-9.2.2/bin/DataBaseds 2 -ORBendPoint giop:tcp::10000

    [Install]
    WantedBy=tango.target

    # /ect/systemd/system/tango-accesscontrol.timer
    [Timer]
    OnActiveSec=3

    [Install]
    WantedBy=tango.target

timer is needed because we have to wait before database is ready to accept requests

    # /etc/systemd/system/tango-accesscontrol.service
    [Unit]
    Description=TangoAccessControl device server
    Wants=tango-db
    After=tango-db
    StopWhenUnneeded=true

    [Service]
    Environment=TANGO_HOST=localhost:10000
    ExecStart=/opt/tango-9.2.2/bin/TangoAccessControl 1

A service unit for Starter device server can also be defined:

    # /etc/systemd/system/tango-starter.service
    [Unit]
    Description=Starter device server
    After=tango-accesscontrol.service
    Requires=tango-db.service
    Requires=tango-accesscontrol.service

    [Service]
    Restart=always
    RestartSec=10
    User=tango
    Environment=TANGO_HOST=localhost:10000
    ExecStart=/usr/local/bin/Starter tangobox

Finally combine everything into a single target:

    # /etc/systemd/system/tango.target
    [Unit]
    Description=Tango development environment target
    Requires=tango-db.service
    Requires=tango-starter.service
    Requires=tango-accesscontrol.timer
    Requires=tango-test.timer

    [Install]
    #WantedBy=multi-user.target

Then these entities must be enabled and started:

    $> sudo systemctl enable {each timer and service}
    $> sudo systemctl start tango.target

systemd unit files may be generated when the device server is built. For instance as it is done in our tango-maven-archetype

Defining Tango servers as systemd units can be also very useful for production.