Add c3d2 options to module at lib/default.nix

Options are for assigning deterministic addresses, statistics
collection, MOTD, /etc/hosts, etc.

host-registry.nix

@@ -0,0 +1,7 @@
+# Registry of C3D2 machines.
+
+let hosts = [ "adc" "grafana" "server7" "tox" ];
+in {
+  hqPublic = hosts;
+  hqPrivate = hosts;
+}

hosts/containers/grafana/configuration.nix

@@ -2,12 +2,19 @@
 
 {
   imports = [
+    ../../../lib
     ../../../lib/lxc-container.nix
     ../../../lib/shared.nix
     ../../../lib/admins.nix
     ../../../lib/hail.nix
   ];
 
+  c3d2 = {
+    isInHq = true;
+    mapHqHosts = true;
+    hq.interface = "eth0";
+  };
+
   networking.hostName = "grafana";
   networking.useNetworkd = true;
   # Needs IPv4 for obtaining certs?

hosts/server7/configuration.nix

@@ -4,6 +4,7 @@ let yggaddr = import ./yggaddr.nix;
 in {
   imports = [
     <nixpkgs/nixos/modules/profiles/minimal.nix>
+    ../../lib
     ../../lib/hq.nix
     ../../lib/default-gateway.nix
     ../../lib/emery.nix
@@ -16,6 +17,15 @@ in {
     ./nix-serve.nix
   ];
 
+  c3d2 = {
+    isInHq = true;
+    mapHqHosts = true;
+    hq = {
+      interface = "br0";
+      statistics.enable = true;
+    };
+  };
+
   # Route IPv6
   boot.kernel.sysctl."net.ipv6.conf.all.forwarding" = 1;
   # Obtain global IPv6 despite being a router myself
@@ -77,14 +87,7 @@ in {
 
   environment.systemPackages = with pkgs; [ tmux htop vim gitMinimal nixfmt ];
 
-  services.collectd = {
-    enable = true;
-    autoLoadPlugin = true;
-    extraConfig = ''
-      HostName "${config.networking.hostName}"
-      FQDNLookup false
-      Interval 10
-
+  services.collectd.extraConfig = ''
     LoadPlugin sensors
     LoadPlugin memory
     LoadPlugin irq
@@ -101,12 +104,7 @@ in {
     LoadPlugin cgroups
     LoadPlugin vmem
     LoadPlugin interface
-      LoadPlugin network
-      <Plugin "network">
-        Server "grafana.hq.c3d2.de" "25826"
-      </Plugin>
   '';
-  };
 
   boot.tmpOnTmpfs = true;
 

hosts/server7/containers/adc/default.nix

@@ -15,7 +15,7 @@
     plugins.history.enable = true;
     plugins.welcome = {
       enable = true;
-      motd = builtins.readFile ../../../../lib/motd;
+      motd = config.users.motd;
     };
   };
 

hosts/server7/containers/default.nix

@@ -21,7 +21,14 @@ let
         localAddress6 = "${yggaddr.prefix}:${hextet0}:${hextet1}:c3d2/64";
         # Generate a deterministic IPv6 address for the container.
         # This address is accessible within HQ and Yggdrasil but not from ARPANET.
-        config = import (./. + "/${name}");
+        config = { ... }: {
+          imports = [ ../../../lib (./. + "/${name}") ];
+          c3d2 = {
+            isInHq = true;
+            mapHqHosts = true;
+            hq.interface = "eth0";
+          };
+        };
       };
     };
 

lib/default.nix

@@ -0,0 +1,170 @@
+# This module is for use by all C3D2 machines.
+# That includes physical servers, VMs, containers, and personal machines.
+#
+
+{ config, lib, ... }:
+
+let
+  hqPrefix64 = "fd23:42:c3d2:523";
+  # TODO: Is this stable? Is there a better place to specifiy this?
+
+  # Generate a deterministic IPv6 address for a 64 bit prefix
+  # and seed string. Prefix must not contain trailing ':'.
+  toIpv6Address = prefix64: seed:
+    with builtins;
+    let
+      digest = builtins.hashString "sha256" seed;
+      hextets = map (i: substring (4 * i) 4 digest) [ 0 1 2 3 ];
+    in concatStringsSep ":" ([ prefix64 ] ++ hextets);
+
+  # Generate a deterministic public IPv6 addresses
+  # for the HQ networking using a seed string.
+  toHqPrivateAddress = toIpv6Address hqPrefix64;
+
+  /* # Generate a deterministic public IPv6 addresses
+     # for the HQ networking using a seed string.
+     toHqPublicAddress = toIpv6Address publicPrefix64;
+
+     # Generate a deterministic public IPv6 addresses
+     # for the HQ networking using a seed string.
+     toserver7YggdrasilAddress = toIpv6Address server7YggrasilPrefix64;
+  */
+
+  cfg = config.c3d2;
+
+in {
+
+  options.c3d2 = with lib;
+    with lib.types; {
+
+      isInHq = mkEnableOption "HQ presence";
+
+      enableMotd = mkOption {
+        type = bool;
+        default = cfg.isInHq;
+        defaultText = literalExample "config.c3d2.isInHq";
+      };
+
+      mapPublicHosts = mkOption {
+        type = bool;
+        default = false;
+        description = ''
+          Whether to add all external HQ host mappings to /etc/hosts.
+        '';
+      };
+
+      mapHqHosts = mkOption {
+        type = bool;
+        default = false;
+        description = ''
+          Whether to add all internal HQ host mappings to /etc/hosts.
+        '';
+      };
+
+      hq = {
+
+        /* externalInterface = mkOption {
+             type = nullOr str;
+             default = null;
+             example = "eth0";
+             description = ''
+               Configure the given interface name with an external IP address.
+             '';
+           };
+        */
+
+        interface = mkOption {
+          type = nullOr str;
+          default = null;
+          example = "eth0";
+          description = ''
+            Configure the given interface name with an internal IP address.
+          '';
+        };
+
+        statistics = { enable = mkEnableOption "statistics collection"; };
+
+      };
+
+    };
+
+  config = let
+    cfg = config.c3d2;
+    hostRegistry = import ../host-registry.nix;
+    mkIfIsInHq = lib.mkIf cfg.isInHq;
+  in {
+
+    assertions = [{
+      assertion = let
+        check = hostName: hostName == config.networking.hostName;
+        checkRegistry = list: builtins.any check list;
+      in cfg.isInHq -> checkRegistry hostRegistry.hqPrivate;
+      message = "${config.networking.hostName} is not registered in ${
+          toString ../host-registry.nix
+        }";
+    }];
+
+    networking.defaultGateway = mkIfIsInHq "172.22.99.4";
+
+    networking.domain = mkIfIsInHq "hq.c3d2.de";
+
+    users.motd = lib.mkIf cfg.enableMotd (builtins.readFile ./motd);
+
+    networking.hosts = let
+      mapHostsNamesToAttrs = f: list: builtins.listToAttrs (map f list);
+
+      /* hqPublicHosts = mapHostsNamesToAttrs (hostName: {
+           name = toHqPublicAddress hostName;
+           value = [ "${hostName}.hq.c3d2.de" hostName ];
+         }) hostRegistry.hqPublic;
+      */
+
+      hqPrivateHosts = mapHostsNamesToAttrs (hostName: {
+        name = toHqPrivateAddress hostName;
+        value = [ "${hostName}.hq" hostName ];
+      }) hostRegistry.hqPrivate;
+
+    in if cfg.mapHqHosts then hqPrivateHosts else { };
+
+    networking.interfaces =
+      /* (if cfg.hq.externalInterface == null then
+           { }
+         else {
+           "${cfg.hq.externalInterface}" = {
+             ipv6.addresses = [{
+               address = toHqPublicAddress config.networking.hostName;
+               prefixLength = 64;
+             }];
+           };
+         }) //
+      */
+      (if cfg.hq.interface == null then
+        { }
+      else {
+        "${cfg.hq.interface}" = {
+          ipv6.addresses = [{
+            address = toHqPrivateAddress config.networking.hostName;
+            prefixLength = 64;
+          }];
+        };
+      });
+
+    services.collectd = lib.mkIf cfg.hq.statistics.enable {
+      enable = true;
+      autoLoadPlugin = true;
+      extraConfig = ''
+        HostName "${config.networking.hostName}"
+        FQDNLookup false
+        Interval 10
+
+        LoadPlugin network
+        <Plugin "network">
+          Server "grafana.hq" "25826"
+        </Plugin>
+      '';
+    };
+
+  };
+
+  meta.maintainers = with lib.maintainers; [ ehmry ];
+}

lib/hq.nix

@@ -5,7 +5,6 @@ let
   notServer7 = config.networking.hostName != "server7";
   port = toString config.services.nix-serve.port;
 in {
-  networking.domain = "hq.c3d2.de";
 
   nix = {
     binaryCaches = [ ]
@@ -23,5 +22,4 @@ in {
     ./yggdrasil-hq.nix
   ];
 
-  users.motd = builtins.readFile ./motd;
 }