nixos/doc: convert assertions and warnings section to CommonMark

3 files changed, 41 insertions, 75 deletions

diff --git a/nixos/doc/manual/development/assertions.section.md b/nixos/doc/manual/development/assertions.section.md
new file mode 100644
index 00000000000..cc6d81e5699
--- /dev/null
+++ b/nixos/doc/manual/development/assertions.section.md
@@ -0,0 +1,40 @@
+# Warnings and Assertions {#sec-assertions}
+
+When configuration problems are detectable in a module, it is a good idea to write an assertion or warning. Doing so provides clear feedback to the user and prevents errors after the build.
+
+Although Nix has the `abort` and `builtins.trace` [functions](https://nixos.org/nix/manual/#ssec-builtins) to perform such tasks, they are not ideally suited for NixOS modules. Instead of these functions, you can declare your warnings and assertions using the NixOS module system.
+
+## Warnings {#sec-assertions-warnings}
+
+This is an example of using `warnings`.
+
+```nix
+{ config, lib, ... }:
+{
+  config = lib.mkIf config.services.foo.enable {
+    warnings =
+      if config.services.foo.bar
+      then [ ''You have enabled the bar feature of the foo service.
+               This is known to cause some specific problems in certain situations.
+               '' ]
+      else [];
+  }
+}
+```
+
+## Assertions {#sec-assertions-assetions}
+
+This example, extracted from the [`syslogd` module](https://github.com/NixOS/nixpkgs/blob/release-17.09/nixos/modules/services/logging/syslogd.nix) shows how to use `assertions`. Since there can only be one active syslog daemon at a time, an assertion is useful to prevent such a broken system from being built.
+
+```nix
+{ config, lib, ... }:
+{
+  config = lib.mkIf config.services.syslogd.enable {
+    assertions =
+      [ { assertion = !config.services.rsyslogd.enable;
+          message = "rsyslogd conflicts with syslogd";
+        }
+      ];
+  }
+}
+```
diff --git a/nixos/doc/manual/development/assertions.xml b/nixos/doc/manual/development/assertions.xml
deleted file mode 100644
index 32f90cf2e7c..00000000000
--- a/nixos/doc/manual/development/assertions.xml
+++ /dev/null
@@ -1,74 +0,0 @@
-<section xmlns="http://docbook.org/ns/docbook"
-        xmlns:xlink="http://www.w3.org/1999/xlink"
-        xmlns:xi="http://www.w3.org/2001/XInclude"
-        version="5.0"
-        xml:id="sec-assertions">
- <title>Warnings and Assertions</title>
-
- <para>
-  When configuration problems are detectable in a module, it is a good idea to
-  write an assertion or warning. Doing so provides clear feedback to the user
-  and prevents errors after the build.
- </para>
-
- <para>
-  Although Nix has the <literal>abort</literal> and
-  <literal>builtins.trace</literal>
-  <link xlink:href="https://nixos.org/nix/manual/#ssec-builtins">functions</link>
-  to perform such tasks, they are not ideally suited for NixOS modules. Instead
-  of these functions, you can declare your warnings and assertions using the
-  NixOS module system.
- </para>
-
- <section xml:id="sec-assertions-warnings">
-  <title>Warnings</title>
-
-  <para>
-   This is an example of using <literal>warnings</literal>.
-  </para>
-
-<programlisting>
-<![CDATA[
-{ config, lib, ... }:
-{
-  config = lib.mkIf config.services.foo.enable {
-    warnings =
-      if config.services.foo.bar
-      then [ ''You have enabled the bar feature of the foo service.
-               This is known to cause some specific problems in certain situations.
-               '' ]
-      else [];
-  }
-}
-]]>
-</programlisting>
- </section>
-
- <section xml:id="sec-assertions-assertions">
-  <title>Assertions</title>
-
-  <para>
-   This example, extracted from the
-   <link xlink:href="https://github.com/NixOS/nixpkgs/blob/release-17.09/nixos/modules/services/logging/syslogd.nix">
-   <literal>syslogd</literal> module </link> shows how to use
-   <literal>assertions</literal>. Since there can only be one active syslog
-   daemon at a time, an assertion is useful to prevent such a broken system
-   from being built.
-  </para>
-
-<programlisting>
-<![CDATA[
-{ config, lib, ... }:
-{
-  config = lib.mkIf config.services.syslogd.enable {
-    assertions =
-      [ { assertion = !config.services.rsyslogd.enable;
-          message = "rsyslogd conflicts with syslogd";
-        }
-      ];
-  }
-}
-]]>
-</programlisting>
- </section>
-</section>
diff --git a/nixos/doc/manual/development/writing-modules.xml b/nixos/doc/manual/development/writing-modules.xml
index fad4637f51f..04497db77b8 100644
--- a/nixos/doc/manual/development/writing-modules.xml
+++ b/nixos/doc/manual/development/writing-modules.xml
@@ -182,7 +182,7 @@ in {
  <xi:include href="option-declarations.xml" />
  <xi:include href="option-types.xml" />
  <xi:include href="option-def.xml" />
- <xi:include href="assertions.xml" />
+ <xi:include href="../from_md/development/assertions.section.xml" />
  <xi:include href="meta-attributes.xml" />
  <xi:include href="importing-modules.xml" />
  <xi:include href="replace-modules.xml" />