Merge pull request #141549 from bobvanderlinden/docker-daemon-config

nixos/docker: add daemon.settings option

nixos/doc/manual/from_md/release-notes/rl-2205.section.xml

···
           <literal>writers.writePyPy2</literal> needs to be used.
         </para>
       </listitem>
+      <listitem>
+        <para>
+          If you previously used
+          <literal>/etc/docker/daemon.json</literal>, you need to
+          incorporate the changes into the new option
+          <literal>virtualisation.docker.daemon.settings</literal>.
+        </para>
+      </listitem>
     </itemizedlist>
   </section>
   <section xml:id="sec-release-22.05-notable-changes">

nixos/doc/manual/release-notes/rl-2205.section.md

···
 - The `writers.writePython2` and corresponding `writers.writePython2Bin` convenience functions to create executable Python 2 scripts in the store were removed in preparation of removal of the Python 2 interpreter.
   Scripts have to be converted to Python 3 for use with `writers.writePython3` or `writers.writePyPy2` needs to be used.
 
+- If you previously used `/etc/docker/daemon.json`, you need to incorporate the changes into the new option `virtualisation.docker.daemon.settings`.
+
 ## Other Notable Changes {#sec-release-22.05-notable-changes}
 
 - The option [services.redis.servers](#opt-services.redis.servers) was added

nixos/modules/virtualisation/docker.nix

···
 
   cfg = config.virtualisation.docker;
   proxy_env = config.networking.proxy.envVars;
-
+  settingsFormat = pkgs.formats.json {};
+  daemonSettingsFile = settingsFormat.generate "daemon.json" cfg.daemon.settings;
 in
 
 {
···
             <literal>--restart=always</literal> flag to work. If this option is
             disabled, docker might be started on demand by socket activation.
           '';
+      };
+
+    daemon.settings =
+      mkOption {
+        type = settingsFormat.type;
+        default = { };
+        example = {
+          ipv6 = true;
+          "fixed-cidr-v6" = "fd00::/80";
+        };
+        description = ''
+          Configuration for docker daemon. The attributes are serialized to JSON used as daemon.conf.
+          See https://docs.docker.com/engine/reference/commandline/dockerd/#daemon-configuration-file
+        '';
       };
 
     enableNvidia =
···
             ""
             ''
               ${cfg.package}/bin/dockerd \
-                --group=docker \
-                --host=fd:// \
-                --log-driver=${cfg.logDriver} \
-                ${optionalString (cfg.storageDriver != null) "--storage-driver=${cfg.storageDriver}"} \
-                ${optionalString cfg.liveRestore "--live-restore" } \
-                ${optionalString cfg.enableNvidia "--add-runtime nvidia=${pkgs.nvidia-docker}/bin/nvidia-container-runtime" } \
+                --config-file=${daemonSettingsFile} \
                 ${cfg.extraOptions}
             ''];
           ExecReload=[
···
         { assertion = cfg.enableNvidia -> config.hardware.opengl.driSupport32Bit or false;
           message = "Option enableNvidia requires 32bit support libraries";
         }];
+
+      virtualisation.docker.daemon.settings = {
+        group = "docker";
+        hosts = [ "fd://" ];
+        log-driver = mkDefault cfg.logDriver;
+        storage-driver = mkIf (cfg.storageDriver != null) (mkDefault cfg.storageDriver);
+        live-restore = mkDefault cfg.liveRestore;
+        runtimes = mkIf cfg.enableNvidia {
+          nvidia = {
+            path = "${pkgs.nvidia-docker}/bin/nvidia-container-runtime";
+          };
+        };
+      };
     }
   ]);