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Interacting with Walrus (1.4)

Walrus is a storage service included with Eucalyptus that is interface compatible with Amazon's S3. Walrus allows users to store persistent data, organized as buckets and objects (see Amazon's S3 Getting Started Guide for more information). Walrus system options can be modified via the administrator web interface.

If you would like to use Walrus to manage Eucalyptus VM images, you can use Amazon's tools to store/register/delete them from Walrus.

Otherwise, you may use S3 Curl to interact with Walrus directly. S3 Curl is a command line tool that computes the signature and invokes curl.

You may create, delete, list buckets, put, get, delete objects, set access control policies, etc. Please refer to the Amazon S3 documentation for the S3 interface specification.

You will need the perl-Digest-HMAC package for S3 Curl, if it is not already installed on your system.

You will need to modify the file s3curl.pl in your favorite editor to change the hostname endpoint.

For example, change 

my @endpoints = ( 's3.amazonaws.com' );

to 

my @endpoints = ( 'your-host' );

where, your-host is the IP or the hostname on which Walrus runs. For authentication to succeed, it is crucial that your-host is the same as the host portion of the $S3_URL environment variable set by eucarc.

When modifying the file s3curl.pl, please specify just the hostname and not the port number or the entire path (e.g., you would specify xyz.com instead of xyz.com:8773/services/Walrus. However, you need to use the entire path in the command-line when using the tool).

Be sure to source your 'eucarc' file before running the commands below. 

s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY <curl options>

It is preferable to add your credentials to the ".s3curl" config file. Please read the README file bundled with s3curl for details.

  • For example, to create a bucket, 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --put /dev/null -- -s -v $S3_URL/bucketName

where bucketName is the name of the bucket that you want to create.

  • To put an object, 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --put <filename> -- -s -v $S3_URL/bucketName/objectName

where objectName is the name of the object that you want to create.

  • To get the MD5 checksum, size and last modification time for an object. 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --head -- -s -v $S3_URL/bucketName/objectName > object.head

cat object.head
  • To get an object 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --get -- -s -v $S3_URL/bucketName/objectName > object
  • To delete an object, 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --del -- -s -v $S3_URL/bucketName/objectName
  • To delete a bucket, 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --del -- -s -v $S3_URL/bucketName

Note that, according to the S3 specification, a bucket needs to be empty before it can be deleted.

You may pipe the output through "xmlindent" (you might need to install it, if it is not already installed on your system).

  • For example, to get the access control policy for a bucket, 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --get -- -s -v $S3_URL/bucketName?acl | xmlindent > bucket.acl
  • To get the contents of a bucket. 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --get -- -s -v $S3_URL/bucketName  | xmlindent > bucket.list
  • To list all buckets for a user. 
s3curl.pl --id $EC2_ACCESS_KEY --key $EC2_SECRET_KEY --get -- -s -v $S3_URL  | xmlindent > bucketlisting
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