notifications: add type for ACME notification template data

This commit adds a separate type for the data passed to this type of
notification template. Also we make sure that we do not expose any
non-primitive types to the template renderer, any data needed in the
template is mapped into the new dedicated template data type.

This ensures that any changes in types defined in other places do not
leak into the template rendering process by accident.
These changes are also preparation for allowing user-overrides for
notification templates.

This commit also tries to unify the style and naming of template
variables.

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>
Reviewed-by: Maximiliano Sandoval <m.sandoval@proxmox.com>

src/server/notifications/mod.rs

@@ -23,7 +23,7 @@ const SPOOL_DIR: &str = concatcp!(pbs_buildcfg::PROXMOX_BACKUP_STATE_DIR, "/noti
 
 mod template_data;
 
-use template_data::{GcErrTemplateData, GcOkTemplateData};
+use template_data::{AcmeErrTemplateData, CommonData, GcErrTemplateData, GcOkTemplateData};
 
 /// Initialize the notification system by setting context in proxmox_notify
 pub fn init() -> Result<(), Error> {
@@ -489,24 +489,26 @@ pub fn send_updates_available(updates: &[&APTUpdateInfo]) -> Result<(), Error> {
 /// send email on certificate renewal failure.
 pub fn send_certificate_renewal_mail(result: &Result<(), Error>) -> Result<(), Error> {
     let error: String = match result {
-        Err(e) => e.to_string(),
+        Err(e) => format!("{e:#}"),
         _ => return Ok(()),
     };
 
-    let (fqdn, port) = get_server_url();
-
-    let data = json!({
-        "fqdn": fqdn,
-        "port": port,
-        "error": error,
-    });
-
     let metadata = HashMap::from([
         ("hostname".into(), proxmox_sys::nodename().into()),
         ("type".into(), "acme".into()),
     ]);
 
-    let notification = Notification::from_template(Severity::Info, "acme-err", data, metadata);
+    let template_data = AcmeErrTemplateData {
+        common: CommonData::new(),
+        error,
+    };
+
+    let notification = Notification::from_template(
+        Severity::Info,
+        "acme-err",
+        serde_json::to_value(template_data)?,
+        metadata,
+    );
 
     send_notification(notification)?;
     Ok(())

src/server/notifications/template_data.rs

@@ -133,3 +133,14 @@ impl GcErrTemplateData {
         }
     }
 }
+
+/// Template data for the acme-err template.
+#[derive(Serialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct AcmeErrTemplateData {
+    /// Common properties.
+    #[serde(flatten)]
+    pub common: CommonData,
+    /// The error that occured when trying to request the certificate.
+    pub error: String,
+}

templates/default/acme-err-body.txt.hbs

@@ -4,4 +4,4 @@ Error: {{error}}
 
 Please visit the web interface for further details:
 
-<https://{{fqdn}}:{{port}}/#pbsCertificateConfiguration>
+<{{base-url}}/#pbsCertificateConfiguration>