[pbs-devel] [RFC proxmox-backup 20/39] api: reader: fetch chunks based on datastore backend

[Christian Ebner]

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 at proxmox.com>
---
 src/api2/reader/environment.rs | 12 +++++++----
 src/api2/reader/mod.rs         | 38 ++++++++++++++++++++++------------
 2 files changed, 33 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 cc791299c..3417f49be 100644
--- a/src/api2/reader/mod.rs
+++ b/src/api2/reader/mod.rs
@@ -24,7 +24,8 @@ 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_s3_client::S3Client;
 use pbs_tools::json::required_string_param;
 
 use crate::api2::backup::optional_ns_param;
@@ -159,7 +160,7 @@ fn upgrade_to_backup_reader_protocol(
                     worker.clone(),
                     datastore,
                     backup_dir,
-                );
+                )?;
 
                 env.debug = debug;
 
@@ -320,17 +321,10 @@ 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()
@@ -342,6 +336,24 @@ fn download_chunk(
     .boxed()
 }
 
+async fn fetch_from_object_store(s3_client: &S3Client, digest: &[u8; 32]) -> Result<Body, Error> {
+    if let Some(response) = s3_client.get_object(digest.into()).await? {
+        return Ok(response.content);
+    }
+    bail!("cannot find chunk with digest {}", hex::encode(digest));
+}
+
+fn load_from_filesystem(env: &ReaderEnvironment, digest: &[u8; 32]) -> Result<Body, Error> {
+    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 {path2:?} failed: {err}"))?;
+    Ok(Body::from(data))
+}
+
 /* this is too slow
 fn download_chunk_old(
     _parts: Parts,
-- 
2.39.5