[pbs-devel] [RFC proxmox-backup 14/39] datastore: allow to get the backend for a datastore

[Christian Ebner]

Implements an enum with variants Filesystem and S3 to distinguish
between available backends. Filesystem will be used as default, if no
backend is configured in the datastores configuration. If the
datastore has an s3 backend configured, the backend method will
instantiate and s3 client and return it with the S3 variant.

This allows to instantiate the client once, keeping and reusing the
same open connection to the api for the lifetime of task or job, e.g.
in the backup writer/readers runtime environment.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-datastore/Cargo.toml       |  1 +
 pbs-datastore/src/datastore.rs | 46 ++++++++++++++++++++++++++++++++--
 pbs-datastore/src/lib.rs       |  1 +
 3 files changed, 46 insertions(+), 2 deletions(-)

diff --git a/pbs-datastore/Cargo.toml b/pbs-datastore/Cargo.toml
index 7623adc28..3ee06c9bb 100644
--- a/pbs-datastore/Cargo.toml
+++ b/pbs-datastore/Cargo.toml
@@ -44,4 +44,5 @@ pbs-api-types.workspace = true
 pbs-buildcfg.workspace = true
 pbs-config.workspace = true
 pbs-key-config.workspace = true
+pbs-s3-client.workspace = true
 pbs-tools.workspace = true
diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index cbf78ecb6..42d27d249 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -8,6 +8,7 @@ use std::time::Duration;
 
 use anyhow::{bail, format_err, Context, Error};
 use nix::unistd::{unlinkat, UnlinkatFlags};
+use pbs_s3_client::{S3Client, S3ClientOptions};
 use pbs_tools::lru_cache::LruCache;
 use tracing::{info, warn};
 
@@ -23,8 +24,9 @@ use proxmox_worker_task::WorkerTaskContext;
 
 use pbs_api_types::{
     ArchiveType, Authid, BackupGroupDeleteStats, BackupNamespace, BackupType, ChunkOrder,
-    DataStoreConfig, DatastoreFSyncLevel, DatastoreTuning, GarbageCollectionStatus,
-    MaintenanceMode, MaintenanceType, Operation, UPID,
+    DataStoreConfig, DatastoreBackendConfig, DatastoreFSyncLevel, DatastoreTuning,
+    GarbageCollectionStatus, MaintenanceMode, MaintenanceType, Operation, S3ClientConfig,
+    S3ClientSecretsConfig, UPID,
 };
 use pbs_config::BackupLockGuard;
 
@@ -125,6 +127,7 @@ pub struct DataStoreImpl {
     chunk_order: ChunkOrder,
     last_digest: Option<[u8; 32]>,
     sync_level: DatastoreFSyncLevel,
+    backend_config: DatastoreBackendConfig,
 }
 
 impl DataStoreImpl {
@@ -139,6 +142,7 @@ impl DataStoreImpl {
             chunk_order: Default::default(),
             last_digest: None,
             sync_level: Default::default(),
+            backend_config: Default::default(),
         })
     }
 }
@@ -194,6 +198,12 @@ impl Drop for DataStore {
     }
 }
 
+#[derive(Clone)]
+pub enum DatastoreBackend {
+    Filesystem,
+    S3(Arc<S3Client>),
+}
+
 impl DataStore {
     // This one just panics on everything
     #[doc(hidden)]
@@ -204,6 +214,32 @@ impl DataStore {
         })
     }
 
+    /// Get the backend for this datastore based on it's configuration
+    pub fn backend(&self) -> Result<DatastoreBackend, Error> {
+        let backend_type = match self.inner.backend_config {
+            DatastoreBackendConfig::Filesystem => DatastoreBackend::Filesystem,
+            DatastoreBackendConfig::S3(ref s3_client_id) => {
+                let (config, _config_digest) = pbs_config::s3::config()?;
+                let (secrets, _secrets_digest) = pbs_config::s3::secrets_config()?;
+                let config: S3ClientConfig = config.lookup("s3client", s3_client_id)?;
+                let secrets: S3ClientSecretsConfig = secrets.lookup("s3secrets", s3_client_id)?;
+                let options = S3ClientOptions {
+                    host: config.host,
+                    port: config.port,
+                    bucket: config.bucket,
+                    region: config.region.unwrap_or("us-west-1".to_string()),
+                    fingerprint: config.fingerprint,
+                    access_key: config.access_key,
+                    secret_key: secrets.secret_key,
+                };
+                let s3_client = S3Client::new(options)?;
+                DatastoreBackend::S3(Arc::new(s3_client))
+            }
+        };
+
+        Ok(backend_type)
+    }
+
     pub fn lookup_datastore(
         name: &str,
         operation: Option<Operation>,
@@ -381,6 +417,11 @@ impl DataStore {
                 .parse_property_string(config.tuning.as_deref().unwrap_or(""))?,
         )?;
 
+        let backend_config = match config.backend {
+            Some(config) => config.parse()?,
+            None => Default::default(),
+        };
+
         Ok(DataStoreImpl {
             chunk_store,
             gc_mutex: Mutex::new(()),
@@ -389,6 +430,7 @@ impl DataStore {
             chunk_order: tuning.chunk_order.unwrap_or_default(),
             last_digest,
             sync_level: tuning.sync_level.unwrap_or_default(),
+            backend_config,
         })
     }
 
diff --git a/pbs-datastore/src/lib.rs b/pbs-datastore/src/lib.rs
index 5014b6c09..e6f65575b 100644
--- a/pbs-datastore/src/lib.rs
+++ b/pbs-datastore/src/lib.rs
@@ -203,6 +203,7 @@ pub use store_progress::StoreProgress;
 mod datastore;
 pub use datastore::{
     check_backup_owner, ensure_datastore_is_mounted, get_datastore_mount_status, DataStore,
+    DatastoreBackend,
 };
 
 mod hierarchy;
-- 
2.39.5