[pdm-devel] [RFC PATCH datacenter-manager] server: api: resources: use root cause for errors for remote fetching

[Dominik Csapak]

On 9/10/25 10:15 AM, Wolfgang Bumiller wrote:
> On Tue, Sep 09, 2025 at 10:25:51AM +0200, Dominik Csapak wrote:
>> when we can't reach a remote for any reason, we want to return the error
>> as a string here over the API. Since most errors that can occur here are
>> client/network related (wrong credentials, no route to host, timeout,
>> etc.) converting this error directly to a string gives us
>> errors like:
>>
>> `client error (Connect)`
>>
>> which is not really helpful most of the time.
>> Instead if we use the `root_cause()`, we get the most underlying error
>>
>> e.g.
>>
>> `error connecting to https://0.0.0.0:8006/ - tcp connect error: No route to host (os error 113)`
>>
>> which is much more helpful.
>>
>> We could also think about printing the whole error chain, but in my test
>> cases here this was not more helpful, e.g. i got two times the above
>> `client error (Connect)` and once the root cause from above.
> 
> Curious, because from a quick grep, `client error (*)` comes from hyper.
> Otherwise I'd say it may have been one our own error types or
> one-too-many same `.context()` calls.
> 
> I'm still not sure this is a good idea though, as we may still lose some
> useful contest. I wish anyhow had an easy method to just shave off a
> single layer.
> 
> What if we do this, but first throw in a:
> 
>      tracing::debug!("{error:?}");
> 
> just so we still have the option to see everything if we need to?

just to clarify: you want me to use root_cause and additionally log the 
error into the debug tracing? (not returning the whole `chain()` here)

> 
>>
>> Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
>> ---
>>   server/src/api/resources.rs | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/server/src/api/resources.rs b/server/src/api/resources.rs
>> index 98c4dea..cca8bcb 100644
>> --- a/server/src/api/resources.rs
>> +++ b/server/src/api/resources.rs
>> @@ -245,7 +245,7 @@ pub(crate) async fn get_resources_impl(
>>           let handle = tokio::spawn(async move {
>>               let (mut resources, error) = match get_resources_for_remote(remote, max_age).await {
>>                   Ok(resources) => (resources, None),
>> -                Err(error) => (Vec::new(), Some(error.to_string())),
>> +                Err(error) => (Vec::new(), Some(error.root_cause().to_string())),
>>               };
>>   
>>               if remotes_only {
>> -- 
>> 2.47.2