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Following the upstream documentation for systemd network target: https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget/ It is not supposed to be used as an active unit and it cannot be started directly. Quote from the website: Note that network.target is a passive unit: you cannot start it directly and it is not pulled in by any services that want to make use of the network. Instead, it is pulled in by the network management service itself. Services using the network should hence simply place an After=network.target dependency in their unit files, and avoid any Wants=network.target or even Requires=network.target. This patch changes the documentation to follow the upstream recommendation.
107 lines
3.4 KiB
Text
107 lines
3.4 KiB
Text
[#creating-new-systemd-services]
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= Creating new systemd services
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This example shows how to create a unit file for a custom service. Custom unit files are located in `/etc/systemd/system/` and have a `.service` extension. For example, a custom `foo` service uses `/etc/systemd/system/foo.service` unit file.
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[discrete]
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== Prerequisites
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* You are logged in as a user with administrator-level permissions.
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[discrete]
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== Procedure
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This procedure creates a basic configuration file to control the `foo` service.
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. Create and edit the new configuration file:
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----
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# nano /etc/systemd/system/foo.service
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----
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. The next few steps describe each section its parameters to add to the file:
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.. The `[Unit]` section provides basic information about the service. The `foo` service uses the following parameters:
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`Description`::
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A string describing the unit. _Systemd_ displays this description next to the unit name in the user interface.
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`After`::
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Defines a relationship with a second unit. If you activate the unit, _systemd_ activates it only after the second one. For example, the `foo` service might require network connectivity, which means the `foo` services specifies `network.target` as an `After=` condition.
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The resulting `[Unit]` section looks like this:
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----
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[Unit]
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Description=My custom service
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After=network.target
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----
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.. The `[Service]` section provides instructions on how to control the service. The `foo` service uses the following parameters:
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`Type`::
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Defines the type of _systemd_ service. In this example, the `foo` service is a `simple` service, which starts the service without any special consideration.
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`ExecStart`::
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The command to run to start the service. This includes the full path to the command and arguments to modify the service.
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The resulting `[Service]` section looks like this:
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----
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[Service]
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Type=simple
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ExecStart=/usr/bin/sleep infinity
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----
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.. The `[Install]` section provides instructions on how _systemd_ installs the service. The `foo` service uses the following parameters:
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`WantedBy`::
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Defines which service triggers the custom service if enabled with `systemctl enable`. This is mostly used for starting the custom service on boot. In this example, `foo.service` uses `multi-user.target`, which starts `foo.service` when _systemd_ loads `multi-user.target` on boot.
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. The full `foo.service` file contains the following contents:
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----
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[Unit]
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Description=My custom service
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After=network.target
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[Service]
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Type=simple
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ExecStart=/usr/bin/sleep infinity
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[Install]
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WantedBy=multi-user.target
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----
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Save the file.
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. To make _systemd_ aware of the new service, reload its service files
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----
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# systemctl daemon-reload
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----
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. Start the custom `foo` service:
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----
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# systemctl start foo
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----
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. Check the status of the service to ensure the service is running:
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----
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$ systemctl status foo
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● foo.service - My custom service
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Loaded: loaded (/etc/systemd/system/foo.service; static; vendor preset: disabled)
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Active: active (running) since Thu 2017-12-14 14:09:12 AEST; 6s ago
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Main PID: 31837 (sleep)
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Tasks: 1 (limit: 4915)
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CGroup: /system.slice/foo.service
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└─31837 /usr/bin/sleep infinity
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Dec 14 14:09:12 dansmachine systemd[1]: Started My custom service.
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----
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[discrete]
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== Related Information
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* See link:#common-service-parameters[Common service parameters] for more information about the parameters used in this procedure.
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