61 lines
2.5 KiB
XML
61 lines
2.5 KiB
XML
<section xmlns="http://docbook.org/ns/docbook"
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xmlns:xlink="http://www.w3.org/1999/xlink"
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xmlns:xi="http://www.w3.org/2001/XInclude"
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version="5.0"
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xml:id="sec-declarative-containers">
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<title>Declarative Container Specification</title>
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<para>
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You can also specify containers and their configuration in the host’s
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<filename>configuration.nix</filename>. For example, the following specifies
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that there shall be a container named <literal>database</literal> running
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PostgreSQL:
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<programlisting>
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containers.database =
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{ config =
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{ config, pkgs, ... }:
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{ <xref linkend="opt-services.postgresql.enable"/> = true;
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<xref linkend="opt-services.postgresql.package"/> = pkgs.postgresql_9_6;
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};
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};
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</programlisting>
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If you run <literal>nixos-rebuild switch</literal>, the container will be
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built. If the container was already running, it will be updated in place,
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without rebooting. The container can be configured to start automatically by
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setting <literal>containers.database.autoStart = true</literal> in its
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configuration.
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</para>
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<para>
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By default, declarative containers share the network namespace of the host,
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meaning that they can listen on (privileged) ports. However, they cannot
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change the network configuration. You can give a container its own network as
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follows:
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<programlisting>
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containers.database = {
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<link linkend="opt-containers._name_.privateNetwork">privateNetwork</link> = true;
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<link linkend="opt-containers._name_.hostAddress">hostAddress</link> = "192.168.100.10";
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<link linkend="opt-containers._name_.localAddress">localAddress</link> = "192.168.100.11";
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};
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</programlisting>
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This gives the container a private virtual Ethernet interface with IP address
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<literal>192.168.100.11</literal>, which is hooked up to a virtual Ethernet
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interface on the host with IP address <literal>192.168.100.10</literal>. (See
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the next section for details on container networking.)
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</para>
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<para>
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To disable the container, just remove it from
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<filename>configuration.nix</filename> and run <literal>nixos-rebuild
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switch</literal>. Note that this will not delete the root directory of the
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container in <literal>/var/lib/containers</literal>. Containers can be
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destroyed using the imperative method: <literal>nixos-container destroy
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foo</literal>.
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</para>
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<para>
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Declarative containers can be started and stopped using the corresponding
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systemd service, e.g. <literal>systemctl start container@database</literal>.
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</para>
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</section>
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