Re: [pbs-devel] [PATCH proxmox-backup 2/3] server/email_notifications: do not panic on template registration

[Thomas Lamprecht <t.lamprecht@proxmox.com>]

On 16.03.21 12:56, Dominik Csapak wrote:
> 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

how can they error?
And any error (with or without this patch) would lead to emails notification not
working anymore, some may seem this as quite fatal error if they do not get notified
on erroneous jobs anymore? We may not be able to do much here, that's why above
question about what the error source can be.

> 
> Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
> ---
>  src/server/email_notifications.rs | 35 +++++++++++++++++++------------
>  1 file changed, 22 insertions(+), 13 deletions(-)
> 
> diff --git a/src/server/email_notifications.rs b/src/server/email_notifications.rs
> index 229443f6..59cd016a 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
>      };
>