(Ruby) AWS S3 File Streaming Upload

Demonstrates how to do a streaming upload from a file to the AWS S3 storage service. The AWS authorization presents some difficulties when the REST request body is to be streamed from a file (or from some other source). The issue is that the SHA-256 hash of the file data must be calculated. There are only two possible ways to do this: (1) stream the file into memory in its entirety and calculate the SHA-256 hash prior to uploading, or (2) pre-calculate the SHA-256 in a streaming fashion, and then provide it to the AWS authentication object.

If the application does NOT pre-compute the SHA-256, then Chilkat (internally) is forced to stream into memory, calculate the SHA-256, and then upload from the in-memory copy of the file.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

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

# This first part is optional.  AWS authentication requires
# the SHA-256 hash of the request body (i.e. the contents of the file
# to be uploaded).  We can choose to pre-calculate the SHA-256 in a streaming fashion
# and then provide it to the authenticator object.  This way, if the file is
# extremely large, it never needs to completely reside in memory.
crypt = Chilkat::CkCrypt2.new()
crypt.put_EncodingMode("hex")
crypt.put_HashAlgorithm("sha-256")
fileToUploadPath = "qa_data/xml/hamlet.xml"
hashStr = crypt.hashFileENC(fileToUploadPath)

rest = Chilkat::CkRest.new()

# Connect to the Amazon AWS REST server.
bTls = true
port = 443
bAutoReconnect = true
success = rest.Connect("s3.amazonaws.com",port,bTls,bAutoReconnect)

# ----------------------------------------------------------------------------
# Important: For buckets created in regions outside us-east-1,
# there are three important changes that need to be made.
# See Working with S3 Buckets in Non-us-east-1 Regions for the details.
# ----------------------------------------------------------------------------

# Provide AWS credentials for the REST call.
authAws = Chilkat::CkAuthAws.new()
authAws.put_AccessKey("AWS_ACCESS_KEY")
authAws.put_SecretKey("AWS_SECRET_KEY")
authAws.put_ServiceName("s3")
# Provide the pre-computed SHA-256 here:
authAws.put_PrecomputedSha256(hashStr)

success = rest.SetAuthAws(authAws)

# Set the bucket name via the HOST header.
# In this case, the bucket name is "chilkat100".
rest.put_Host("chilkat100.s3.amazonaws.com")

fileStream = Chilkat::CkStream.new()
fileStream.put_SourceFile(fileToUploadPath)

# Upload to the S3 Storage service.
# If the application provided the SHA-256 hash of the file contents (as shown above)
# then file is streamed and never has to completely reside in memory.
# If the application did NOT provide the SHA-256, then Chilkat will (internally) 
# load the entire file into memory, calculate the SHA-256, and then upload.
responseStr = rest.fullRequestStream("PUT","/hamlet.xml",fileStream)
if (rest.get_LastMethodSuccess() != true)
    print rest.lastErrorText() + "\n";
    exit
end

# When successful, the S3 Storage service will respond with a 200 response code,
# with an XML body.  
if (rest.get_ResponseStatusCode() == 200)
    print responseStr + "\n";
    print "File uploaded." + "\n";
else
    # Examine the request/response to see what happened.
    print "response status code = " + rest.get_ResponseStatusCode().to_s() + "\n";
    print "response status text = " + rest.responseStatusText() + "\n";
    print "response header: " + rest.responseHeader() + "\n";
    print "response body: " + responseStr + "\n";
    print "---" + "\n";
    print "LastRequestStartLine: " + rest.lastRequestStartLine() + "\n";
    print "LastRequestHeader: " + rest.lastRequestHeader() + "\n";
end