services/s3: Don't load_from_env if users already inputs

Cargo.toml

@@ -9,6 +9,10 @@ repository = "https://github.com/datafuselabs/opendal"
 keywords = ["storage", "data", "s3"]
 categories = ["filesystem"]
 
+[[bench]]
+name = "s3"
+harness = false
+
 [dependencies]
 async-compat = "0.2.1"
 async-trait = "0.1.52"
@@ -30,3 +34,4 @@ uuid = { version = "0.8.2", features = ["serde", "v4"] }
 anyhow = "1.0"
 rand = "0.8.5"
 sha2 = "0.10.1"
+criterion = { version = "0.3", features = ["async", "async_tokio"] }

benches/s3.rs

@@ -0,0 +1,36 @@
+// Copyright 2022 Datafuse Labs.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+use criterion::{criterion_group, criterion_main, Criterion};
+use opendal::credential::Credential;
+
+async fn init() {
+    opendal::services::s3::Backend::build()
+        .bucket("test")
+        .region("test")
+        .credential(Credential::hmac("test", "test"))
+        .finish()
+        .await
+        .unwrap();
+}
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let runtime = tokio::runtime::Runtime::new().unwrap();
+
+    c.bench_function("s3_init", |b| {
+        b.to_async(&runtime).iter(|| init());
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);

src/services/s3.rs

@@ -119,20 +119,47 @@ impl Builder {
             String::new()
         };
 
-        // Load config from environment, including:
+        // Config Loader will load config from environment.
+        //
+        // We will take user's input first if any. If there is no user input, we
+        // will fallback to the aws default load chain like the following:
+        //
         // - Environment variables: AWS_ACCESS_KEY_ID, AWS_SECRET_ACCESS_KEY, and AWS_REGION
         // - The default credentials files located in ~/.aws/config and ~/.aws/credentials (location can vary per platform)
         // - Web Identity Token credentials from the environment or container (including EKS)
         // - ECS Container Credentials (IAM roles for tasks)
         // - EC2 Instance Metadata Service (IAM Roles attached to instance)
-        let cfg = aws_config::load_from_env().await;
-
-        let mut cfg = AwsS3::config::Builder::from(&cfg);
+        //
+        // Please keep in mind that the config loader only detect region and credentials.
+        let mut cfg_loader = aws_config::ConfigLoader::default();
 
         if let Some(region) = &self.region {
-            cfg = cfg.region(AwsS3::Region::new(Cow::from(region.clone())));
+            cfg_loader = cfg_loader.region(AwsS3::Region::new(Cow::from(region.clone())));
+        }
+
+        if let Some(cred) = &self.credential {
+            match cred {
+                Credential::HMAC {
+                    access_key_id,
+                    secret_access_key,
+                } => {
+                    cfg_loader = cfg_loader.credentials_provider(AwsS3::Credentials::from_keys(
+                        access_key_id,
+                        secret_access_key,
+                        None,
+                    ));
+                }
+                _ => {
+                    return Err(Error::BackendConfigurationInvalid {
+                        key: "credential".to_string(),
+                        value: "".to_string(),
+                    });
+                }
+            }
         }
 
+        let mut cfg = AwsS3::config::Builder::from(&cfg_loader.load().await);
+
         // Load users input first, if user not input, we will fallback to aws
         // default load logic.
         if let Some(endpoint) = &self.endpoint {
@@ -170,29 +197,6 @@ impl Builder {
             cfg = cfg.endpoint_resolver(AwsS3::Endpoint::immutable(uri));
         }
 
-        // Load users input first, if user not input, we will fallback to aws
-        // default load logic.
-        if let Some(cred) = &self.credential {
-            match cred {
-                Credential::HMAC {
-                    access_key_id,
-                    secret_access_key,
-                } => {
-                    cfg = cfg.credentials_provider(AwsS3::Credentials::from_keys(
-                        access_key_id,
-                        secret_access_key,
-                        None,
-                    ));
-                }
-                _ => {
-                    return Err(Error::BackendConfigurationInvalid {
-                        key: "credential".to_string(),
-                        value: "".to_string(),
-                    });
-                }
-            }
-        }
-
         Ok(Arc::new(Backend {
             // Make `/` as the default of root.
             root,