treefile: Add an edition

This will allow us to clean up some defaults and change some semantics.
In particular, I'd like to add an opinionated mechanism to copy files
from git into the build.

For now, `edition: "2024"` just flips on `tmp-is-dir: true` and fixes
`boot-location`.

Signed-off-by: Colin Walters <[email protected]>

docs/treefile.md

@@ -14,6 +14,10 @@ Jenkins to operate on them as it changes.
 
 It supports the following parameters:
 
+ * `edition`: string, optional: If not set, the default value is
+   treated as `2014`. The only other supported value is `2024`, which
+   changes some defaults.
+
  * `ref`: string, mandatory: Holds a string which will be the name of
    the branch for the content. This field supports variable substitution.
 
@@ -47,7 +51,8 @@ It supports the following parameters:
       upgrading from very old versions of libostree.
     * "modules": Kernel data goes just in `/usr/lib/modules`.  Use
       this for new systems, and systems that don't need to be upgraded
-      from very old libostree versions.
+      from very old libostree versions. This is the default for editions 2024
+      and above.
 
  * `etc-group-members`: Array of strings, optional: Unix groups in this
    list will be stored in `/etc/group` instead of `/usr/lib/group`.  Use
@@ -441,8 +446,8 @@ It supports the following parameters:
    supported. For more details, see the OSTree manual:
    https://ostreedev.github.io/ostree/deployment/
 
- * `tmp-is-dir`: boolean, optional: Defaults to `false`.  By default,
-   rpm-ostree creates symlink `/tmp` → `sysroot/tmp`.  When set to `true`,
+ * `tmp-is-dir`: boolean, optional: Defaults to `false` in editions < 2024, otherwise `true`.
+   By default, rpm-ostree creates symlink `/tmp` → `sysroot/tmp`.  When set to `true`,
    `/tmp` will be a regular directory, which allows the `systemd` unit
    `tmp.mount` to mount it as `tmpfs`. It's more flexible to leave it
    as a directory, and further, we don't want to encourage `/sysroot`

rust/src/treefile.rs

@@ -160,6 +160,12 @@ fn treefile_parse_stream<R: io::Read>(
         treefile.check_groups = Some(CheckGroups::None);
     }
 
+    // Change these defaults for 2024 edition
+    if treefile.edition.unwrap_or_default() >= Edition::Twenty24 {
+        treefile.boot_location = Some(BootLocation::Modules);
+        treefile.tmp_is_dir = Some(true);
+    }
+
     // Special handling for packages, since we allow whitespace within items.
     // We also canonicalize bootstrap_packages to packages here so it's
     // easier to append the basearch packages after.
@@ -389,6 +395,7 @@ fn treefile_merge(dest: &mut TreeComposeConfig, src: &mut TreeComposeConfig) {
     }
 
     merge_basics!(
+        edition,
         treeref,
         basearch,
         rojig,
@@ -2391,10 +2398,22 @@ impl std::ops::DerefMut for TreeComposeConfig {
     }
 }
 
+#[derive(Serialize, Deserialize, Debug, Default, PartialEq, Eq, Copy, Clone, PartialOrd, Ord)]
+#[serde(rename_all = "kebab-case")]
+pub(crate) enum Edition {
+    #[serde(rename = "2014")]
+    #[default]
+    Twenty14,
+    #[serde(rename = "2024")]
+    Twenty24,
+}
+
 /// These fields are only useful when composing a new ostree commit.
 #[derive(Clone, Serialize, Deserialize, Debug, Default, PartialEq, Eq)]
 #[serde(rename_all = "kebab-case")]
 pub(crate) struct BaseComposeConfigFields {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(crate) edition: Option<Edition>,
     // Compose controls
     #[serde(rename = "ref")]
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -3792,6 +3811,17 @@ conditional-include:
         assert!(tf.parsed.base.tmp_is_dir.unwrap());
     }
 
+    #[test]
+    fn test_edition() {
+        let workdir = tempfile::tempdir().unwrap();
+        let workdir: &Utf8Path = workdir.path().try_into().unwrap();
+        let tf = indoc! { r#"
+            edition: "2024"
+        "#};
+        let tf = new_test_treefile(workdir, tf, None).unwrap();
+        assert!(tf.parsed.base.tmp_is_dir.unwrap());
+    }
+
     #[test]
     fn test_check_passwd() {
         {