examples: Improve examples for s3

examples/s3.rs

@@ -13,26 +13,53 @@
 // limitations under the License.
 
 //! Example for initiating a s3 backend.
+use std::env;
 use std::sync::Arc;
 
 use anyhow::Result;
+use futures::AsyncReadExt;
+use log::info;
 use opendal::credential::Credential;
 use opendal::services::s3;
 use opendal::services::s3::Builder;
 use opendal::Accessor;
-use opendal::Object;
 use opendal::Operator;
 
 #[tokio::main]
 async fn main() -> Result<()> {
+    if env::var("RUST_LOG").is_err() {
+        env::set_var("RUST_LOG", "debug");
+    }
+    env_logger::init();
+
+    println!(
+        r#"OpenDAL S3 Example.
+
+Available Environment Values:
+
+RUST_LOG: log level
+OPENDAL_S3_ROOT: root path, default: /
+OPENDAL_S3_BUCKET: bukcet name, required.
+OPENDAL_S3_ENDPOINT: endpoint of s3 service, default: https://s3.amazonaws.com
+OPENDAL_S3_REGION: region of s3 service, could be auto detected.
+OPENDAL_S3_ACCESS_KEY_ID: access key id of s3 service, could be auto detected.
+OPENDAL_S3_SECRET_ACCESS_KEY: secret access key of s3 service, could be auto detected.
+
+Examples:
+
+OPENDAL_S3_BUCKET=opendal OPENDAL_S3_ACCESS_KEY_ID=minioadmin OPENDAL_S3_SECRET_ACCESS_KEY=minioadminx OPENDAL_S3_ENDPOINT=http://127.0.0.1:9900 OPENDAL_S3_REGION=test cargo run --example s3
+
+    "#
+    );
+
     // Create s3 backend builder.
     let mut builder: Builder = s3::Backend::build();
     // Set the root for s3, all operations will happen under this root.
     //
     // NOTE: the root must be absolute path.
-    builder.root("/path/to/dir");
+    builder.root(&env::var("OPENDAL_S3_ROOT").unwrap_or_default());
     // Set the bucket name, this is required.
-    builder.bucket("bucket_name");
+    builder.bucket(&env::var("OPENDAL_S3_BUCKET").expect("env OPENDAL_S3_BUCKET not set"));
     // Set the endpoint.
     //
     // For examples:
@@ -42,21 +69,57 @@ async fn main() -> Result<()> {
     // - "https://cos.ap-seoul.myqcloud.com"
     //
     // Default to "https://s3.amazonaws.com"
-    builder.endpoint("https://s3.amazonaws.com");
+    builder.endpoint(
+        &env::var("OPENDAL_S3_ENDPOINT").unwrap_or_else(|_| "https://s3.amazonaws.com".to_string()),
+    );
+    // Set the region in we have this env.
+    if let Ok(region) = env::var("OPENDAL_S3_REGION") {
+        builder.region(&region);
+    }
     // Set the credential.
     //
     // OpenDAL will try load credential from the env.
     // If credential not set and no valid credential in env, OpenDAL will
     // send request without signing like anonymous user.
-    builder.credential(Credential::hmac("access_key_id", "secret_access_key"));
+    builder.credential(Credential::hmac(
+        &env::var("OPENDAL_S3_ACCESS_KEY_ID").expect("env OPENDAL_S3_ACCESS_KEY_ID not set"),
+        &env::var("OPENDAL_S3_SECRET_ACCESS_KEY")
+            .expect("env OPENDAL_S3_SECRET_ACCESS_KEY not set"),
+    ));
     // Build the `Accessor`.
     let accessor: Arc<dyn Accessor> = builder.finish().await?;
 
     // `Accessor` provides the low level APIs, we will use `Operator` normally.
     let op: Operator = Operator::new(accessor);
 
+    let path = uuid::Uuid::new_v4().to_string();
+
     // Create an object handle to start operation on object.
-    let _: Object = op.object("test_file");
+    info!("try to write file: {}", &path);
+    op.object(&path)
+        .writer()
+        .write_bytes(String::from("Hello, world!").into_bytes())
+        .await?;
+    info!("write file successful!");
+
+    info!("try to read file: {}", &path);
+    let mut content = String::new();
+    op.object(&path)
+        .reader()
+        .read_to_string(&mut content)
+        .await?;
+    info!("read file successful, content: {}", content);
+
+    info!("try to get file metadata: {}", &path);
+    let meta = op.object(&path).metadata().await?;
+    info!(
+        "get file metadata successful, size: {}B",
+        meta.content_length()
+    );
+
+    info!("try to delete file: {}", &path);
+    let _ = op.object(&path).delete().await?;
+    info!("delete file successful");
 
     Ok(())
 }