Rust

S3 Get Object Metadata, such as ETag

See more Amazon S3 (new) Examples

Demonstrates how to get an S3 object's metadata using a HEAD request. Rust

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

let rest = chilkat::Rest::new();

// Connect to the Amazon AWS REST server in the desired region.
// In this case we connect to S3 in the "us-west-2" region.
let b_tls = true;
let port = 443;
let b_auto_reconnect = true;
let _ = rest.connect("s3-us-west-2.amazonaws.com", port, b_tls, b_auto_reconnect).is_ok();

// Provide AWS credentials.
let auth_aws = chilkat::AuthAws::new();
auth_aws.set_access_key("AWS_ACCESS_KEY");
auth_aws.set_secret_key("AWS_SECRET_KEY");
auth_aws.set_service_name("s3");

// This particular bucket is in the Oregon region, as opposed to the US Standard,
// therefore the Region must be set appropriately.
// Also note that we connected to "s3-us-west-2.amazonaws.com".
auth_aws.set_region("us-west-2");

let _ = rest.set_auth_aws(&auth_aws).is_ok();

// Note: The above REST connection and setup of the AWS credentials
// can be done once.  After connecting, any number of REST calls can be made.
// The "auto reconnect" property passed to rest.Connect indicates that if
// the connection is lost, a REST method call will automatically reconnect
// if needed.
// --------------------------------------------------------------------------

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat.ocean".
// Note that the Host header should use "bucketName.s3.amazonaws.com", not "bucketName.s3-us-west-2.amazonaws.com"
rest.set_host("chilkat.ocean.s3.amazonaws.com");

// Our object is "starfish.jpg".
// Get the metadata.
// Since we are sending a HEAD request, we shouldn't use any of the Full* methods.
// Instead, send the request, then just read the response header.
if rest.send_req_no_body("HEAD", "/starfish.jpg").is_err() {
    println!("{}", rest.last_error_text());
    return;
}

// Now get the response header.
let status_code = rest.read_response_header();
if status_code < 0 {
    println!("{}", rest.last_error_text());
    return;
}

// When successful, the S3 Storage service will respond with a 200 response code,
// with an XML body.  
if status_code != 200 {
    // Examine the request/response to see what happened.
    println!("response status code = {}", status_code);
    println!("response status text = {}", rest.response_status_text());
    println!("response header: {}", rest.response_header());
    return;
}

// The response header contains information about the S3 object.
// For example:

// 	HTTP/1.1 200 OK
// 	x-amz-id-2: GrV/hrB2EUkBlWc0h3JDdmVIrYDXfPC7CGvo/qSVRmYRPwilAOry8+4r2YWl4xJfa1HRYXrP808=
// 	x-amz-request-id: 4BDC6D6AEA0BDEF3
// 	Date: Mon, 13 May 2019 22:03:13 GMT
// 	Last-Modified: Mon, 10 Nov 2014 16:10:23 GMT
// 	ETag: "2e9c59dbf2662367dc97dfdda85da048"
// 	Accept-Ranges: bytes
// 	Content-Type: image/jpg
// 	Content-Length: 6229
// 	Server: AmazonS3

// Get the ETag response header value:
let etag = rest.response_hdr_by_name("ETag").unwrap_or_default();
println!("ETag: {}", etag);