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

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

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?

> 
> Signed-off-by: Dominik Csapak <d.csapak@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


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