124 lines
3.8 KiB
XML
124 lines
3.8 KiB
XML
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<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-imperative-containers">
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<title>Imperative Container Management</title>
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<para>We’ll cover imperative container management using
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<command>nixos-container</command> first. You create a container with
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identifier <literal>foo</literal> as follows:
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<screen>
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$ nixos-container create foo
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</screen>
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This creates the container’s root directory in
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<filename>/var/lib/containers/foo</filename> and a small configuration
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file in <filename>/etc/containers/foo.conf</filename>. It also builds
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the container’s initial system configuration and stores it in
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<filename>/nix/var/nix/profiles/per-container/foo/system</filename>. You
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can modify the initial configuration of the container on the command
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line. For instance, to create a container that has
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<command>sshd</command> running, with the given public key for
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<literal>root</literal>:
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<screen>
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$ nixos-container create foo --config 'services.openssh.enable = true; \
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users.extraUsers.root.openssh.authorizedKeys.keys = ["ssh-dss AAAAB3N…"];'
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</screen>
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</para>
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<para>Creating a container does not start it. To start the container,
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run:
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<screen>
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$ nixos-container start foo
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</screen>
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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@<replaceable>container-name</replaceable>.service</literal>.
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Thus, if something went wrong, you can get status info using
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<command>systemctl</command>:
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<screen>
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$ systemctl status container@foo
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</screen>
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</para>
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<para>If the container has started succesfully, you can log in as
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root using the <command>root-login</command> operation:
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<screen>
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$ nixos-container root-login foo
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[root@foo:~]#
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</screen>
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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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<command>login</command> operation, which is available to all users on
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the host:
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<screen>
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$ nixos-container login foo
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foo login: alice
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Password: ***
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</screen>
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With <command>nixos-container run</command>, you can execute arbitrary
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commands in the container:
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<screen>
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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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</screen>
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</para>
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<para>There are several ways to change the configuration of the
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container. First, on the host, you can edit
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<literal>/var/lib/container/<replaceable>name</replaceable>/etc/nixos/configuration.nix</literal>,
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and run
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<screen>
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$ nixos-container update foo
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</screen>
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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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<screen>
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$ nixos-container update foo --config 'services.httpd.enable = true; \
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services.httpd.adminAddr = "foo@example.org";'
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$ curl http://$(nixos-container show-ip foo)/
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">…
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</screen>
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However, note that this will overwrite the container’s
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<filename>/etc/nixos/configuration.nix</filename>.</para>
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<para>Alternatively, you can change the configuration from within the
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container itself by running <command>nixos-rebuild switch</command>
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inside the container. Note that the container by default does not have
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a copy of the NixOS channel, so you should run <command>nix-channel
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--update</command> first.</para>
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<para>Containers can be stopped and started using
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<literal>nixos-container stop</literal> and <literal>nixos-container
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start</literal>, respectively, or by using
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<command>systemctl</command> on the container’s service unit. To
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destroy a container, including its file system, do
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<screen>
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$ nixos-container destroy foo
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</screen>
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</para>
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</section>
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