WIP: podman: Configure auto-updates

configuration/services/gitea.nix

@@ -17,7 +17,7 @@
 
     containers = {
       gitea = {
-        image = "gitea/gitea:latest";
+        image = "docker.io/gitea/gitea:latest";
         volumes = [ "gitea:/data:Z" "/etc/localtime:/etc/localtime:ro" ];
         dependsOn = [ "postgres" ];
 
@@ -35,6 +35,11 @@
           DOMAIN = "gitea.tlater.net";
           SSH_PORT = "2221";
         };
+
+        extraOptions = [
+          "--replace"
+          "--label" "io.containers.autoupdate=image"
+        ];
       };
 
       postgres = {

modules/default.nix

@@ -1,5 +1,5 @@
 { ... }:
 
 {
-  imports = [ ./virtualisation/pods.nix ];
+  imports = [ ./virtualisation/pods.nix ./virtualisation/oci-containers.nix ];
 }

modules/virtualisation/oci-containers.nix

@@ -0,0 +1,350 @@
+# Pulled from my own modified fork of nixpkgs, awaiting merge
+# upstream.
+
+{ config, options, lib, pkgs, ... }:
+
+with lib;
+let
+  cfg = config.virtualisation.oci-containers;
+  proxy_env = config.networking.proxy.envVars;
+
+  defaultBackend = options.virtualisation.oci-containers.backend.default;
+
+  containerOptions =
+    { ... }: {
+
+      options = {
+
+        image = mkOption {
+          type = with types; str;
+          description = "OCI 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 = "Override 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";
+            }
+        '';
+        };
+
+        environmentFiles = mkOption {
+          type = with types; listOf path;
+          default = [];
+          description = "Environment files for this container.";
+          example = literalExample ''
+            [
+              /path/to/.env
+              /path/to/.env.secret
+            ]
+        '';
+        };
+
+        log-driver = mkOption {
+          type = types.str;
+          default = "journald";
+          description = ''
+            Logging driver for the container.  The default of
+            <literal>"journald"</literal> means that the container's logs will be
+            handled as part of the systemd unit.
+
+            For more details and a full list of logging drivers, refer to respective backends documentation.
+
+            For Docker:
+            <link xlink:href="https://docs.docker.com/engine/reference/run/#logging-drivers---log-driver">Docker engine documentation</link>
+
+            For Podman:
+            Refer to the docker-run(1) man page.
+          '';
+        };
+
+        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 be 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>virtualisation.oci-containers.containers</literal>.
+          '';
+          example = literalExample ''
+            virtualisation.oci-containers.containers = {
+              node1 = {};
+              node2 = {
+                dependsOn = [ "node1" ];
+              }
+            }
+          '';
+        };
+
+        extraOptions = mkOption {
+          type = with types; listOf str;
+          default = [];
+          description = "Extra options for <command>${defaultBackend} run</command>.";
+          example = literalExample ''
+            ["--network=host"]
+          '';
+        };
+
+        autoStart = mkOption {
+          type = types.bool;
+          default = true;
+          description = ''
+            When enabled, the container is automatically started on boot.
+            If this option is set to false, the container has to be started on-demand via its service.
+          '';
+        };
+      };
+    };
+
+  mkService = name: container: let
+    dependsOn = map (x: "${cfg.backend}-${x}.service") container.dependsOn;
+  in {
+    wantedBy = [] ++ optional (container.autoStart) "multi-user.target";
+    after = lib.optionals (cfg.backend == "docker") [ "docker.service" "docker.socket" ] ++ dependsOn;
+    requires = dependsOn;
+    environment = proxy_env;
+
+    path =
+      if cfg.backend == "docker" then [ config.virtualisation.docker.package ]
+      else if cfg.backend == "podman" then [ config.virtualisation.podman.package ]
+      else throw "Unhandled backend: ${cfg.backend}";
+
+    preStart = ''
+      ${cfg.backend} rm -f ${name} || true
+      ${optionalString (container.imageFile != null) ''
+        ${cfg.backend} load -i ${container.imageFile}
+        ''}
+      '';
+
+    # Podman likes knowing what systemd unit launched its container,
+    # so that it can auto-update containers and restart them.
+    #
+    # Sadly, the NixOS `script` option doesn't expose the systemd
+    # syntax `%n` that would expose the unit location, so we pass it
+    # as $1 in a scriptArg.
+    scriptArgs = lib.optionals (cfg.backend == "podman") "%n";
+
+    script = concatStringsSep " \\\n  " ([
+      "exec ${cfg.backend} run"
+      "--rm"
+      "--name=${escapeShellArg name}"
+      "--log-driver=${container.log-driver}"
+    ] ++ optional (container.entrypoint != null)
+      "--entrypoint=${escapeShellArg container.entrypoint}"
+      ++ (mapAttrsToList (k: v: "-e ${escapeShellArg k}=${escapeShellArg v}") container.environment)
+      ++ optional (cfg.backend == "podman") ''-e 'PODMAN_SYSTEMD_UNIT'="$1"''
+      ++ map (f: "--env-file ${escapeShellArg f}") container.environmentFiles
+      ++ 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}"
+      ++ map escapeShellArg container.extraOptions
+      ++ [container.image]
+      ++ map escapeShellArg container.cmd
+    );
+
+    preStop = "[ $SERVICE_RESULT = success ] || ${cfg.backend} stop ${name}";
+    postStop = "${cfg.backend} rm -f ${name} || true";
+
+    serviceConfig = {
+      StandardOutput = "null";
+      StandardError = "null";
+
+      ### 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 = "always";
+    };
+  };
+
+in {
+  imports = [
+    (
+      lib.mkChangedOptionModule
+      [ "docker-containers"  ]
+      [ "virtualisation" "oci-containers" ]
+      (oldcfg: {
+        backend = "docker";
+        containers = lib.mapAttrs (n: v: builtins.removeAttrs (v // {
+          extraOptions = v.extraDockerOptions or [];
+        }) [ "extraDockerOptions" ]) oldcfg.docker-containers;
+      })
+    )
+  ];
+  disabledModules = [ "virtualisation/oci-containers.nix" ];
+
+  options.virtualisation.oci-containers = {
+
+    backend = mkOption {
+      type = types.enum [ "podman" "docker" ];
+      default =
+        # TODO: Once https://github.com/NixOS/nixpkgs/issues/77925 is resolved default to podman
+        # if versionAtLeast config.system.stateVersion "20.09" then "podman"
+        # else "docker";
+        "docker";
+      description = "The underlying Docker implementation to use.";
+    };
+
+    containers = mkOption {
+      default = {};
+      type = types.attrsOf (types.submodule containerOptions);
+      description = "OCI (Docker) containers to run as systemd services.";
+    };
+
+  };
+
+  config = lib.mkIf (cfg.containers != {}) (lib.mkMerge [
+    {
+      systemd.services = mapAttrs' (n: v: nameValuePair "${cfg.backend}-${n}" (mkService n v)) cfg.containers;
+    }
+    (lib.mkIf (cfg.backend == "podman") {
+      virtualisation.podman.enable = true;
+    })
+    (lib.mkIf (cfg.backend == "docker") {
+      virtualisation.docker.enable = true;
+    })
+  ]);
+
+}