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Add module for networked docker containers

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The upstream docker-containers options don't support networks, and
they're quite difficult to patch from downstream.

For now, vendor it a little, and patch it up to support networks.

It's unlikely that upstream would take this patch, since it is a
little hacky.
This commit is contained in:
Tristan Daniël Maat 2020-02-08 18:38:20 +09:00
parent ccf48bd68b
commit 9d209f5dda
Signed by: tlater
GPG key ID: 49670FD774E43268
2 changed files with 308 additions and 0 deletions
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2
etc/nixos/configuration.nix
View file

@ -5,6 +5,8 @@
./hardware-configuration.nix
./linode.nix
<nixpkgs/nixos/modules/profiles/headless.nix>
./modules/networked-docker-containers.nix
];
networking = {

306
etc/nixos/modules/networked-docker-containers.nix Normal file
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@ -0,0 +1,306 @@
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.networked-docker-containers;
networkedDockerContainer =
{ ... }: {
options = {
image = mkOption {
type = with types; str;
description = "Docker image to run.";
example = "library/hello-world";
};
imageFile = mkOption {
type = with types; nullOr package;
default = null;
description = ''
Path to an image file to load instead of pulling from a registry.
If defined, do not pull from registry.
You still need to set the <literal>image</literal> attribute, as it
will be used as the image name for docker to start a container.
'';
example = literalExample "pkgs.dockerTools.buildDockerImage {...};";
};
cmd = mkOption {
type = with types; listOf str;
default = [];
description = "Commandline arguments to pass to the image's entrypoint.";
example = literalExample ''
["--port=9000"]
'';
};
entrypoint = mkOption {
type = with types; nullOr str;
description = "Overwrite the default entrypoint of the image.";
default = null;
example = "/bin/my-app";
};
environment = mkOption {
type = with types; attrsOf str;
default = {};
description = "Environment variables to set for this container.";
example = literalExample ''
{
DATABASE_HOST = "db.example.com";
DATABASE_PORT = "3306";
}
'';
};
log-driver = mkOption {
type = types.str;
default = "none";
description = ''
Logging driver for the container. The default of
<literal>"none"</literal> means that the container's logs will be
handled as part of the systemd unit. Setting this to
<literal>"journald"</literal> will result in duplicate logging, but
the container's logs will be visible to the <command>docker
logs</command> command.
For more details and a full list of logging drivers, refer to the
<link xlink:href="https://docs.docker.com/engine/reference/run/#logging-drivers---log-driver">
Docker engine documentation</link>
'';
};
networks = mkOption {
type = with types; listOf str;
default = [];
description = ''
Docker networks to create and connect this container to.
The first network in this list will be connected with
<literal>--network=</literal>, others after container
creation with <command>docker network connect</command>.
Any networks will be created if they do not exist before
the container is started.
'';
};
ports = mkOption {
type = with types; listOf str;
default = [];
description = ''
Network ports to publish from the container to the outer host.
Valid formats:
<itemizedlist>
<listitem>
<para>
<literal>&lt;ip&gt;:&lt;hostPort&gt;:&lt;containerPort&gt;</literal>
</para>
</listitem>
<listitem>
<para>
<literal>&lt;ip&gt;::&lt;containerPort&gt;</literal>
</para>
</listitem>
<listitem>
<para>
<literal>&lt;hostPort&gt;:&lt;containerPort&gt;</literal>
</para>
</listitem>
<listitem>
<para>
<literal>&lt;containerPort&gt;</literal>
</para>
</listitem>
</itemizedlist>
Both <literal>hostPort</literal> and
<literal>containerPort</literal> can be specified as a range of
ports. When specifying ranges for both, the number of container
ports in the range must match the number of host ports in the
range. Example: <literal>1234-1236:1234-1236/tcp</literal>
When specifying a range for <literal>hostPort</literal> only, the
<literal>containerPort</literal> must <emphasis>not</emphasis> be a
range. In this case, the container port is published somewhere
within the specified <literal>hostPort</literal> range. Example:
<literal>1234-1236:1234/tcp</literal>
Refer to the
<link xlink:href="https://docs.docker.com/engine/reference/run/#expose-incoming-ports">
Docker engine documentation</link> for full details.
'';
example = literalExample ''
[
"8080:9000"
]
'';
};
user = mkOption {
type = with types; nullOr str;
default = null;
description = ''
Override the username or UID (and optionally groupname or GID) used
in the container.
'';
example = "nobody:nogroup";
};
volumes = mkOption {
type = with types; listOf str;
default = [];
description = ''
List of volumes to attach to this container.
Note that this is a list of <literal>"src:dst"</literal> strings to
allow for <literal>src</literal> to refer to
<literal>/nix/store</literal> paths, which would difficult with an
attribute set. There are also a variety of mount options available
as a third field; please refer to the
<link xlink:href="https://docs.docker.com/engine/reference/run/#volume-shared-filesystems">
docker engine documentation</link> for details.
'';
example = literalExample ''
[
"volume_name:/path/inside/container"
"/path/on/host:/path/inside/container"
]
'';
};
workdir = mkOption {
type = with types; nullOr str;
default = null;
description = "Override the default working directory for the container.";
example = "/var/lib/hello_world";
};
dependsOn = mkOption {
type = with types; listOf str;
default = [];
description = ''
Define which other containers this one depends on. They will be added to both After and Requires for the unit.
Use the same name as the attribute under <literal>services.docker-containers</literal>.
'';
example = literalExample ''
services.docker-containers = {
node1 = {};
node2 = {
dependsOn = [ "node1" ];
}
}
'';
};
extraDockerOptions = mkOption {
type = with types; listOf str;
default = [];
description = "Extra options for <command>docker run</command>.";
example = literalExample ''
["--network=host"]
'';
};
};
};
mkService = name: container: let
mkAfter = map (x: "docker-${x}.service") container.dependsOn;
in
rec {
wantedBy = [ "multi-user.target" ];
after = [ "docker.service" "docker.socket" "docker-networks.service" ] ++ mkAfter;
requires = after;
serviceConfig = {
ExecStart = [ "${pkgs.docker}/bin/docker start -a ${name}" ];
ExecStartPre = [
"-${pkgs.docker}/bin/docker rm -f ${name}"
"-${pkgs.docker}/bin/docker image prune -f"
] ++ (
optional (container.imageFile != null)
[ "${pkgs.docker}/bin/docker load -i ${container.imageFile}" ]
) ++ [
(
concatStringsSep " \\\n " (
[
"${pkgs.docker}/bin/docker create"
"--rm"
"--name=${name}"
"--log-driver=${container.log-driver}"
] ++ optional (container.entrypoint != null)
"--entrypoint=${escapeShellArg container.entrypoint}"
++ (mapAttrsToList (k: v: "-e ${escapeShellArg k}=${escapeShellArg v}") container.environment)
++ map (p: "-p ${escapeShellArg p}") container.ports
++ optional (container.user != null) "-u ${escapeShellArg container.user}"
++ map (v: "-v ${escapeShellArg v}") container.volumes
++ optional (container.workdir != null) "-w ${escapeShellArg container.workdir}"
++ optional (container.networks != []) "--network=${escapeShellArg (builtins.head container.networks)}"
++ map escapeShellArg container.extraDockerOptions
++ [ container.image ]
++ map escapeShellArg container.cmd
)
)
] ++ map (n: "${pkgs.docker}/bin/docker network connect ${escapeShellArg n} ${name}") (drop 1 container.networks);
ExecStop = ''${pkgs.bash}/bin/sh -c "[ $SERVICE_RESULT = success ] || ${pkgs.docker}/bin/docker stop ${name}"'';
ExecStopPost = "-${pkgs.docker}/bin/docker rm -f ${name}";
### There is no generalized way of supporting `reload` for docker
### containers. Some containers may respond well to SIGHUP sent to their
### init process, but it is not guaranteed; some apps have other reload
### mechanisms, some don't have a reload signal at all, and some docker
### images just have broken signal handling. The best compromise in this
### case is probably to leave ExecReload undefined, so `systemctl reload`
### will at least result in an error instead of potentially undefined
### behaviour.
###
### Advanced users can still override this part of the unit to implement
### a custom reload handler, since the result of all this is a normal
### systemd service from the perspective of the NixOS module system.
###
# ExecReload = ...;
###
TimeoutStartSec = 0;
TimeoutStopSec = 120;
Restart = "no";
};
};
in
{
options.networked-docker-containers = mkOption {
default = {};
type = types.attrsOf (types.submodule networkedDockerContainer);
description = "Docker containers to run as systemd services.";
};
config = mkIf (cfg != {}) {
systemd.services = mapAttrs' (n: v: nameValuePair "docker-${n}" (mkService n v)) cfg // {
"docker-networks" = rec {
after = [ "docker.service" "docker.socket" ];
requires = after;
serviceConfig = {
Type = "oneshot";
ExecStart = map (
n: ''${pkgs.bash}/bin/sh -c "${pkgs.docker}/bin/docker network inspect ${escapeShellArg n} > /dev/null || \
${pkgs.docker}/bin/docker network create ${escapeShellArg n}"''
) (unique (flatten (mapAttrsToList (_: c: c.networks) cfg)));
};
};
};
virtualisation.docker.enable = true;
};
}