Re: [pbs-devel] [PATCH proxmox-backup v8 14/45] api: reader: fetch chunks based on datastore backend

[Christian Ebner <c.ebner@proxmox.com>]

On 7/18/25 12:03 PM, Lukas Wagner wrote:
> On  2025-07-18 11:58, Christian Ebner wrote:
>> On 7/18/25 10:38 AM, Lukas Wagner wrote:
>>> One comment inline, but nothing prohibitive of a R-b:
>>>
>>> Reviewed-by: Lukas Wagner <l.wagner@proxmox.com>
>>>
>>>
>>> On  2025-07-15 14:53, Christian Ebner wrote:
>>>> Read the chunk based on the datastores backend, reading from local
>>>> filesystem or fetching from S3 object store.
>>>>
>>>> Signed-off-by: Christian Ebner <c.ebner@proxmox.com>
>>>> ---
>>>> changes since version 7:
>>>> - no changes
>>>>
>>>>    src/api2/reader/environment.rs | 12 ++++++----
>>>>    src/api2/reader/mod.rs         | 41 +++++++++++++++++++++++-----------
>>>>    2 files changed, 36 insertions(+), 17 deletions(-)
>>>>
>>>> diff --git a/src/api2/reader/environment.rs b/src/api2/reader/environment.rs
>>>> index 3b2f06f43..8924352b0 100644
>>>> --- a/src/api2/reader/environment.rs
>>>> +++ b/src/api2/reader/environment.rs
>>>> @@ -1,13 +1,14 @@
>>>>    use std::collections::HashSet;
>>>>    use std::sync::{Arc, RwLock};
>>>>    +use anyhow::Error;
>>>>    use serde_json::{json, Value};
>>>>      use proxmox_router::{RpcEnvironment, RpcEnvironmentType};
>>>>      use pbs_api_types::Authid;
>>>>    use pbs_datastore::backup_info::BackupDir;
>>>> -use pbs_datastore::DataStore;
>>>> +use pbs_datastore::{DataStore, DatastoreBackend};
>>>>    use proxmox_rest_server::formatter::*;
>>>>    use proxmox_rest_server::WorkerTask;
>>>>    use tracing::info;
>>>> @@ -23,6 +24,7 @@ pub struct ReaderEnvironment {
>>>>        pub worker: Arc<WorkerTask>,
>>>>        pub datastore: Arc<DataStore>,
>>>>        pub backup_dir: BackupDir,
>>>> +    pub backend: DatastoreBackend,
>>>>        allowed_chunks: Arc<RwLock<HashSet<[u8; 32]>>>,
>>>>    }
>>>>    @@ -33,8 +35,9 @@ impl ReaderEnvironment {
>>>>            worker: Arc<WorkerTask>,
>>>>            datastore: Arc<DataStore>,
>>>>            backup_dir: BackupDir,
>>>> -    ) -> Self {
>>>> -        Self {
>>>> +    ) -> Result<Self, Error> {
>>>> +        let backend = datastore.backend()?;
>>>> +        Ok(Self {
>>>>                result_attributes: json!({}),
>>>>                env_type,
>>>>                auth_id,
>>>> @@ -43,8 +46,9 @@ impl ReaderEnvironment {
>>>>                debug: tracing::enabled!(tracing::Level::DEBUG),
>>>>                formatter: JSON_FORMATTER,
>>>>                backup_dir,
>>>> +            backend,
>>>>                allowed_chunks: Arc::new(RwLock::new(HashSet::new())),
>>>> -        }
>>>> +        })
>>>>        }
>>>>          pub fn log<S: AsRef<str>>(&self, msg: S) {
>>>> diff --git a/src/api2/reader/mod.rs b/src/api2/reader/mod.rs
>>>> index a77216043..997d9ca77 100644
>>>> --- a/src/api2/reader/mod.rs
>>>> +++ b/src/api2/reader/mod.rs
>>>> @@ -3,6 +3,7 @@
>>>>    use anyhow::{bail, format_err, Context, Error};
>>>>    use futures::*;
>>>>    use hex::FromHex;
>>>> +use http_body_util::BodyExt;
>>>>    use hyper::body::Incoming;
>>>>    use hyper::header::{self, HeaderValue, CONNECTION, UPGRADE};
>>>>    use hyper::http::request::Parts;
>>>> @@ -27,8 +28,9 @@ use pbs_api_types::{
>>>>    };
>>>>    use pbs_config::CachedUserInfo;
>>>>    use pbs_datastore::index::IndexFile;
>>>> -use pbs_datastore::{DataStore, PROXMOX_BACKUP_READER_PROTOCOL_ID_V1};
>>>> +use pbs_datastore::{DataStore, DatastoreBackend, PROXMOX_BACKUP_READER_PROTOCOL_ID_V1};
>>>>    use pbs_tools::json::required_string_param;
>>>> +use proxmox_s3_client::S3Client;
>>>>      use crate::api2::backup::optional_ns_param;
>>>>    use crate::api2::helpers;
>>>> @@ -162,7 +164,7 @@ fn upgrade_to_backup_reader_protocol(
>>>>                        worker.clone(),
>>>>                        datastore,
>>>>                        backup_dir,
>>>> -                );
>>>> +                )?;
>>>>                      env.debug = debug;
>>>>    @@ -323,17 +325,10 @@ fn download_chunk(
>>>>                ));
>>>>            }
>>>>    -        let (path, _) = env.datastore.chunk_path(&digest);
>>>> -        let path2 = path.clone();
>>>> -
>>>> -        env.debug(format!("download chunk {:?}", path));
>>>> -
>>>> -        let data =
>>>> -            proxmox_async::runtime::block_in_place(|| std::fs::read(path)).map_err(move |err| {
>>>> -                http_err!(BAD_REQUEST, "reading file {:?} failed: {}", path2, err)
>>>> -            })?;
>>>> -
>>>> -        let body = Body::from(data);
>>>> +        let body = match &env.backend {
>>>> +            DatastoreBackend::Filesystem => load_from_filesystem(env, &digest)?,
>>>> +            DatastoreBackend::S3(s3_client) => fetch_from_object_store(s3_client, &digest).await?,
>>>> +        };
>>>>              // fixme: set other headers ?
>>>>            Ok(Response::builder()
>>>> @@ -345,6 +340,26 @@ fn download_chunk(
>>>>        .boxed()
>>>>    }
>>>>    +async fn fetch_from_object_store(s3_client: &S3Client, digest: &[u8; 32]) -> Result<Body, Error> {
>>>> +    let object_key = pbs_datastore::s3::object_key_from_digest(digest)?;
>>>> +    if let Some(response) = s3_client.get_object(object_key).await? {
>>>
>>> ^ Do we maybe want some kind of retry-logic for retrieving objects as well? Disregard
>>> in case you implement it in a later patch, I'm reviewing this series patch by patch.
>>
>> While a retry might be of interest in case of inter-mitten issues, for the time being I would like to refrain from doing so for the reasons stated in my reply to proxmox-backup patch 0004. If the need for this truly arises, adding this later on should be rather simple. If you already see this as an issue now, I can of course add the retry logic right away.
> 
> No, I'm fine with revisiting this later, e.g. after a potential rollout where we have some initial user feedback. It's still
> experimental after all :)

Yes, could well be that this is needed and makes sense, after all I 
added the put retry logic and rate limiting option only after seeing 
that this is indeed an issue when I encountered errors when uploading to 
fast to Cloudflare R2 object stores, which seems was rather easily 
overwhelm.



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