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132 lines
4.7 KiB
132 lines
4.7 KiB
<section xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xml:id="sec-imperative-containers">
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<title>Imperative Container Management</title>
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<para>
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We’ll cover imperative container management using
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<literal>nixos-container</literal> first. Be aware that container
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management is currently only possible as <literal>root</literal>.
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</para>
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<para>
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You create a container with identifier <literal>foo</literal> as
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follows:
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</para>
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<programlisting>
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# nixos-container create foo
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</programlisting>
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<para>
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This creates the container’s root directory in
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<literal>/var/lib/nixos-containers/foo</literal> and a small
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configuration file in
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<literal>/etc/nixos-containers/foo.conf</literal>. It also builds
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the container’s initial system configuration and stores it in
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<literal>/nix/var/nix/profiles/per-container/foo/system</literal>.
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You can modify the initial configuration of the container on the
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command line. For instance, to create a container that has
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<literal>sshd</literal> running, with the given public key for
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<literal>root</literal>:
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</para>
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<programlisting>
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# nixos-container create foo --config '
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services.openssh.enable = true;
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users.users.root.openssh.authorizedKeys.keys = ["ssh-dss AAAAB3N…"];
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'
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</programlisting>
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<para>
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By default the next free address in the
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<literal>10.233.0.0/16</literal> subnet will be chosen as container
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IP. This behavior can be altered by setting
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<literal>--host-address</literal> and
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<literal>--local-address</literal>:
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</para>
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<programlisting>
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# nixos-container create test --config-file test-container.nix \
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--local-address 10.235.1.2 --host-address 10.235.1.1
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</programlisting>
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<para>
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Creating a container does not start it. To start the container, run:
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</para>
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<programlisting>
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# nixos-container start foo
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</programlisting>
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<para>
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This command will return as soon as the container has booted and has
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reached <literal>multi-user.target</literal>. On the host, the
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container runs within a systemd unit called
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<literal>container@container-name.service</literal>. Thus, if
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something went wrong, you can get status info using
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<literal>systemctl</literal>:
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</para>
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<programlisting>
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# systemctl status container@foo
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</programlisting>
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<para>
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If the container has started successfully, you can log in as root
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using the <literal>root-login</literal> operation:
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</para>
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<programlisting>
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# nixos-container root-login foo
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[root@foo:~]#
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</programlisting>
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<para>
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Note that only root on the host can do this (since there is no
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authentication). You can also get a regular login prompt using the
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<literal>login</literal> operation, which is available to all users
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on the host:
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</para>
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<programlisting>
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# nixos-container login foo
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foo login: alice
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Password: ***
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</programlisting>
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<para>
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With <literal>nixos-container run</literal>, you can execute
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arbitrary commands in the container:
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</para>
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<programlisting>
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# nixos-container run foo -- uname -a
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Linux foo 3.4.82 #1-NixOS SMP Thu Mar 20 14:44:05 UTC 2014 x86_64 GNU/Linux
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</programlisting>
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<para>
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There are several ways to change the configuration of the container.
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First, on the host, you can edit
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<literal>/var/lib/container/name/etc/nixos/configuration.nix</literal>,
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and run
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</para>
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<programlisting>
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# nixos-container update foo
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</programlisting>
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<para>
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This will build and activate the new configuration. You can also
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specify a new configuration on the command line:
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</para>
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<programlisting>
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# nixos-container update foo --config '
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services.httpd.enable = true;
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services.httpd.adminAddr = "foo@example.org";
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networking.firewall.allowedTCPPorts = [ 80 ];
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'
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# curl http://$(nixos-container show-ip foo)/
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">…
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</programlisting>
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<para>
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However, note that this will overwrite the container’s
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<literal>/etc/nixos/configuration.nix</literal>.
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</para>
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<para>
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Alternatively, you can change the configuration from within the
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container itself by running <literal>nixos-rebuild switch</literal>
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inside the container. Note that the container by default does not
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have a copy of the NixOS channel, so you should run
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<literal>nix-channel --update</literal> first.
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</para>
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<para>
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Containers can be stopped and started using
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<literal>nixos-container stop</literal> and
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<literal>nixos-container start</literal>, respectively, or by using
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<literal>systemctl</literal> on the container’s service unit. To
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destroy a container, including its file system, do
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</para>
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<programlisting>
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# nixos-container destroy foo
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</programlisting>
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</section>
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