[pbs-devel] [PATCH proxmox-backup v2 2/5] server/email_notifications: do not panic on template registration

[Dominik Csapak <d.csapak@proxmox.com>]

instead print an error and continue, the rendering functions will error
out if one of the templates could not be registered

if we `.unwrap()` here, it can lead to problems if the templates are
not correct, i.e. we could panic while holding a lock, if something holds
a mutex while this is called for the first time

add a test to catch registration issues during package build

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
changes from v1:
* add test to actually test registering, this will fail
  on package build if the template registering fails

 src/server/email_notifications.rs | 55 +++++++++++++++++++++++--------
 1 file changed, 42 insertions(+), 13 deletions(-)

diff --git a/src/server/email_notifications.rs b/src/server/email_notifications.rs
index 229443f6..cd5a43fe 100644
--- a/src/server/email_notifications.rs
+++ b/src/server/email_notifications.rs
@@ -1,10 +1,11 @@
 use anyhow::Error;
 use serde_json::json;
 
-use handlebars::{Handlebars, Helper, Context, RenderError, RenderContext, Output, HelperResult};
+use handlebars::{Handlebars, Helper, Context, RenderError, RenderContext, Output, HelperResult, TemplateError};
 
 use proxmox::tools::email::sendmail;
 use proxmox::api::schema::parse_property_string;
+use proxmox::try_block;
 
 use crate::{
     config::datastore::DataStoreConfig,
@@ -181,25 +182,33 @@ lazy_static::lazy_static!{
 
     static ref HANDLEBARS: Handlebars<'static> = {
         let mut hb = Handlebars::new();
+        let result: Result<(), TemplateError> = try_block!({
 
-        hb.set_strict_mode(true);
+            hb.set_strict_mode(true);
 
-        hb.register_helper("human-bytes", Box::new(handlebars_humam_bytes_helper));
-        hb.register_helper("relative-percentage", Box::new(handlebars_relative_percentage_helper));
+            hb.register_helper("human-bytes", Box::new(handlebars_humam_bytes_helper));
+            hb.register_helper("relative-percentage", Box::new(handlebars_relative_percentage_helper));
 
-        hb.register_template_string("gc_ok_template", GC_OK_TEMPLATE).unwrap();
-        hb.register_template_string("gc_err_template", GC_ERR_TEMPLATE).unwrap();
+            hb.register_template_string("gc_ok_template", GC_OK_TEMPLATE)?;
+            hb.register_template_string("gc_err_template", GC_ERR_TEMPLATE)?;
 
-        hb.register_template_string("verify_ok_template", VERIFY_OK_TEMPLATE).unwrap();
-        hb.register_template_string("verify_err_template", VERIFY_ERR_TEMPLATE).unwrap();
+            hb.register_template_string("verify_ok_template", VERIFY_OK_TEMPLATE)?;
+            hb.register_template_string("verify_err_template", VERIFY_ERR_TEMPLATE)?;
 
-        hb.register_template_string("sync_ok_template", SYNC_OK_TEMPLATE).unwrap();
-        hb.register_template_string("sync_err_template", SYNC_ERR_TEMPLATE).unwrap();
+            hb.register_template_string("sync_ok_template", SYNC_OK_TEMPLATE)?;
+            hb.register_template_string("sync_err_template", SYNC_ERR_TEMPLATE)?;
 
-        hb.register_template_string("tape_backup_ok_template", TAPE_BACKUP_OK_TEMPLATE).unwrap();
-        hb.register_template_string("tape_backup_err_template", TAPE_BACKUP_ERR_TEMPLATE).unwrap();
+            hb.register_template_string("tape_backup_ok_template", TAPE_BACKUP_OK_TEMPLATE)?;
+            hb.register_template_string("tape_backup_err_template", TAPE_BACKUP_ERR_TEMPLATE)?;
 
-        hb.register_template_string("package_update_template", PACKAGE_UPDATES_TEMPLATE).unwrap();
+            hb.register_template_string("package_update_template", PACKAGE_UPDATES_TEMPLATE)?;
+
+            Ok(())
+        });
+
+        if let Err(err) = result {
+            eprintln!("error during template registration: {}", err);
+        }
 
         hb
     };
@@ -600,3 +609,23 @@ fn handlebars_relative_percentage_helper(
     }
     Ok(())
 }
+
+#[test]
+fn test_template_register() {
+    HANDLEBARS.get_helper("human-bytes").unwrap();
+    HANDLEBARS.get_helper("relative-percentage").unwrap();
+
+    assert!(HANDLEBARS.has_template("gc_ok_template"));
+    assert!(HANDLEBARS.has_template("gc_err_template"));
+
+    assert!(HANDLEBARS.has_template("verify_ok_template"));
+    assert!(HANDLEBARS.has_template("verify_err_template"));
+
+    assert!(HANDLEBARS.has_template("sync_ok_template"));
+    assert!(HANDLEBARS.has_template("sync_err_template"));
+
+    assert!(HANDLEBARS.has_template("tape_backup_ok_template"));
+    assert!(HANDLEBARS.has_template("tape_backup_err_template"));
+
+    assert!(HANDLEBARS.has_template("package_update_template"));
+}
-- 
2.20.1