1 files changed, 201 insertions, 0 deletions
diff --git a/nixos/modules/system/etc/etc.nix b/nixos/modules/system/etc/etc.nix
new file mode 100644
index 00000000000..ed552fecec5
--- /dev/null
+++ b/nixos/modules/system/etc/etc.nix
@@ -0,0 +1,201 @@
+# Management of static files in /etc.
+
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  etc' = filter (f: f.enable) (attrValues config.environment.etc);
+
+  etc = pkgs.runCommandLocal "etc" {
+    # This is needed for the systemd module
+    passthru.targets = map (x: x.target) etc';
+  } /* sh */ ''
+    set -euo pipefail
+
+    makeEtcEntry() {
+      src="$1"
+      target="$2"
+      mode="$3"
+      user="$4"
+      group="$5"
+
+      if [[ "$src" = *'*'* ]]; then
+        # If the source name contains '*', perform globbing.
+        mkdir -p "$out/etc/$target"
+        for fn in $src; do
+            ln -s "$fn" "$out/etc/$target/"
+        done
+      else
+
+        mkdir -p "$out/etc/$(dirname "$target")"
+        if ! [ -e "$out/etc/$target" ]; then
+          ln -s "$src" "$out/etc/$target"
+        else
+          echo "duplicate entry $target -> $src"
+          if [ "$(readlink "$out/etc/$target")" != "$src" ]; then
+            echo "mismatched duplicate entry $(readlink "$out/etc/$target") <-> $src"
+            ret=1
+
+            continue
+          fi
+        fi
+
+        if [ "$mode" != symlink ]; then
+          echo "$mode" > "$out/etc/$target.mode"
+          echo "$user" > "$out/etc/$target.uid"
+          echo "$group" > "$out/etc/$target.gid"
+        fi
+      fi
+    }
+
+    mkdir -p "$out/etc"
+    ${concatMapStringsSep "\n" (etcEntry: escapeShellArgs [
+      "makeEtcEntry"
+      # Force local source paths to be added to the store
+      "${etcEntry.source}"
+      etcEntry.target
+      etcEntry.mode
+      etcEntry.user
+      etcEntry.group
+    ]) etc'}
+  '';
+
+in
+
+{
+
+  imports = [ ../build.nix ];
+
+  ###### interface
+
+  options = {
+
+    environment.etc = mkOption {
+      default = {};
+      example = literalExpression ''
+        { example-configuration-file =
+            { source = "/nix/store/.../etc/dir/file.conf.example";
+              mode = "0440";
+            };
+          "default/useradd".text = "GROUP=100 ...";
+        }
+      '';
+      description = ''
+        Set of files that have to be linked in <filename>/etc</filename>.
+      '';
+
+      type = with types; attrsOf (submodule (
+        { name, config, options, ... }:
+        { options = {
+
+            enable = mkOption {
+              type = types.bool;
+              default = true;
+              description = ''
+                Whether this /etc file should be generated.  This
+                option allows specific /etc files to be disabled.
+              '';
+            };
+
+            target = mkOption {
+              type = types.str;
+              description = ''
+                Name of symlink (relative to
+                <filename>/etc</filename>).  Defaults to the attribute
+                name.
+              '';
+            };
+
+            text = mkOption {
+              default = null;
+              type = types.nullOr types.lines;
+              description = "Text of the file.";
+            };
+
+            source = mkOption {
+              type = types.path;
+              description = "Path of the source file.";
+            };
+
+            mode = mkOption {
+              type = types.str;
+              default = "symlink";
+              example = "0600";
+              description = ''
+                If set to something else than <literal>symlink</literal>,
+                the file is copied instead of symlinked, with the given
+                file mode.
+              '';
+            };
+
+            uid = mkOption {
+              default = 0;
+              type = types.int;
+              description = ''
+                UID of created file. Only takes effect when the file is
+                copied (that is, the mode is not 'symlink').
+                '';
+            };
+
+            gid = mkOption {
+              default = 0;
+              type = types.int;
+              description = ''
+                GID of created file. Only takes effect when the file is
+                copied (that is, the mode is not 'symlink').
+              '';
+            };
+
+            user = mkOption {
+              default = "+${toString config.uid}";
+              type = types.str;
+              description = ''
+                User name of created file.
+                Only takes effect when the file is copied (that is, the mode is not 'symlink').
+                Changing this option takes precedence over <literal>uid</literal>.
+              '';
+            };
+
+            group = mkOption {
+              default = "+${toString config.gid}";
+              type = types.str;
+              description = ''
+                Group name of created file.
+                Only takes effect when the file is copied (that is, the mode is not 'symlink').
+                Changing this option takes precedence over <literal>gid</literal>.
+              '';
+            };
+
+          };
+
+          config = {
+            target = mkDefault name;
+            source = mkIf (config.text != null) (
+              let name' = "etc-" + baseNameOf name;
+              in mkDerivedConfig options.text (pkgs.writeText name')
+            );
+          };
+
+        }));
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = {
+
+    system.build.etc = etc;
+    system.build.etcActivationCommands =
+      ''
+        # Set up the statically computed bits of /etc.
+        echo "setting up /etc..."
+        ${pkgs.perl.withPackages (p: [ p.FileSlurp ])}/bin/perl ${./setup-etc.pl} ${etc}/etc
+      '';
+  };
+
+}