pegasus-s3 - Online in the Cloud

PROGRAM:

NAME

pegasus-s3 - Upload, download, delete objects in Amazon S3

SYNOPSIS

pegasus-s3 help
pegasus-s3 ls [options] URL
pegasus-s3 mkdir [options] URL...
pegasus-s3 rmdir [options] URL...
pegasus-s3 rm [options] [URL...]
pegasus-s3 put [options] FILE URL
pegasus-s3 get [options] URL [FILE]
pegasus-s3 lsup [options] URL
pegasus-s3 rmup [options] URL [UPLOAD]
pegasus-s3 cp [options] SRC... DEST

DESCRIPTION

pegasus-s3 is a client for the Amazon S3 object storage service and any other storage
services that conform to the Amazon S3 API, such as Eucalyptus Walrus.

OPTIONS

Global Options
-h, --help
Show help message for subcommand and exit

-d, --debug
Turn on debugging

-v, --verbose
Show progress messages

-C FILE, --conf=FILE
Path to configuration file

rm Options
-f, --force
If the URL does not exist, then ignore the error.

-F FILE, --file=FILE
File containing a list of URLs to delete

put Options
-c X, --chunksize=X
Set the chunk size for multipart uploads to X MB. A value of 0 disables multipart
uploads. The default is 10MB, the min is 5MB and the max is 1024MB. This parameter
only applies for sites that support multipart uploads (see multipart_uploads
configuration parameter in the CONFIGURATION section). The maximum number of chunks is
10,000, so if you are uploading a large file, then the chunk size is automatically
increased to enable the upload. Choose smaller values to reduce the impact of
transient failures.

-p N, --parallel=N
Use N threads to upload FILE in parallel. The default value is 4, which enables
parallel uploads with 4 threads. This parameter is only valid if the site supports
mulipart uploads and the --chunksize parameter is not 0. Otherwise parallel uploads
are disabled.

-b, --create-bucket
Create the destination bucket if it does not already exist

get Options
-c X, --chunksize=X
Set the chunk size for parallel downloads to X megabytes. A value of 0 will avoid
chunked reads. This option only applies for sites that support ranged downloads (see
ranged_downloads configuration parameter). The default chunk size is 10MB, the min is
1MB and the max is 1024MB. Choose smaller values to reduce the impact of transient
failures.

-p N, --parallel=N
Use N threads to upload FILE in parallel. The default value is 4, which enables
parallel downloads with 4 threads. This parameter is only valid if the site supports
ranged downloads and the --chunksize parameter is not 0. Otherwise parallel downloads
are disabled.

rmup Options
-a, --all
Cancel all uploads for the specified bucket

cp Options
-c, --create-dest
Create the destination bucket if it does not exist.

-r, --recursive
If SRC is a bucket, copy all of the keys in that bucket to DEST. In that case DEST
must be a bucket.

-f, --force
If DEST exists, then overwrite it.

SUBCOMMANDS

pegasus-s3 has several subcommands for different storage service operations.

help
The help subcommand lists all available subcommands.

ls
The ls subcommand lists the contents of a URL. If the URL does not contain a bucket,
then all the buckets owned by the user are listed. If the URL contains a bucket, but
no key, then all the keys in the bucket are listed. If the URL contains a bucket and a
key, then all keys in the bucket that begin with the specified key are listed.

mkdir
The mkdir subcommand creates one or more buckets.

rmdir
The rmdir subcommand deletes one or more buckets from the storage service. In order to
delete a bucket, the bucket must be empty.

rm
The rm subcommand deletes one or more keys from the storage service.

put
The put subcommand stores the file specified by FILE in the storage service under the
bucket and key specified by URL. If the URL contains a bucket, but not a key, then the
file name is used as the key.

If a transient failure occurs, then the upload will be retried several times before
pegasus-s3 gives up and fails.

The put subcommand can do both chunked and parallel uploads if the service supports
multipart uploads (see multipart_uploads in the CONFIGURATION section). Currently only
Amazon S3 supports multipart uploads.

This subcommand will check the size of the file to make sure it can be stored before
attempting to store it.

Chunked uploads are useful to reduce the probability of an upload failing. If an
upload is chunked, then pegasus-s3 issues separate PUT requests for each chunk of the
file. Specifying smaller chunks (using --chunksize) will reduce the chances of an
upload failing due to a transient error. Chunksizes can range from 5 MB to 1GB (chunk
sizes smaller than 5 MB produced incomplete uploads on Amazon S3). The maximum number
of chunks for any single file is 10,000, so if a large file is being uploaded with a
small chunksize, then the chunksize will be increased to fit within the 10,000 chunk
limit. By default, the file will be split into 10 MB chunks if the storage service
supports multipart uploads. Chunked uploads can be disabled by specifying a chunksize
of 0. If the upload is chunked, then each chunk is retried independently under
transient failures. If any chunk fails permanently, then the upload is aborted.

Parallel uploads can increase performance for services that support multipart uploads.
In a parallel upload the file is split into N chunks and each chunk is uploaded
concurrently by one of M threads in first-come, first-served fashion. If the chunksize
is set to 0, then parallel uploads are disabled. If M > N, then the actual number of
threads used will be reduced to N. The number of threads can be specified using the
--parallel argument. If --parallel is 1, then only a single thread is used. The
default value is 4. There is no maximum number of threads, but it is likely that the
link will be saturated by 4 to 8 threads.

Under certain circumstances, when a multipart upload fails it could leave behind data
on the server. When a failure occurs the put subcommand will attempt to abort the
upload. If the upload cannot be aborted, then a partial upload may remain on the
server. To check for partial uploads run the lsup subcommand. If you see an upload
that failed in the output of lsup, then run the rmup subcommand to remove it.

get
The get subcommand retrieves an object from the storage service identified by URL and
stores it in the file specified by FILE. If FILE is not specified, then the key is
used as the file name (Note: if the key has slashes, then the file name will be a
relative subdirectory, but pegasus-s3 will not create the subdirectory if it does not
exist).

If a transient failure occurs, then the download will be retried several times before
pegasus-s3 gives up and fails.

The get subcommand can do both chunked and parallel downloads if the service supports
ranged downloads (see ranged_downloads in the CONFIGURATION section). Currently only
Amazon S3 has good support for ranged downloads. Eucalyptus Walrus supports ranged
downloads, but the current release, 1.6, is inconsistent with the Amazon interface and
has a bug that causes ranged downloads to hang in some cases. It is recommended that
ranged downloads not be used with Eucalyptus until these issues are resolved.

Chunked downloads can be used to reduce the probability of a download failing. When a
download is chunked, pegasus-s3 issues separate GET requests for each chunk of the
file. Specifying smaller chunks (using --chunksize) will reduce the chances that a
download will fail to do a transient error. Chunk sizes can range from 1 MB to 1 GB.
By default, a download will be split into 10 MB chunks if the site supports ranged
downloads. Chunked downloads can be disabled by specifying a --chunksize of 0. If a
download is chunked, then each chunk is retried independently under transient
failures. If any chunk fails permanently, then the download is aborted.

Parallel downloads can increase performance for services that support ranged
downloads. In a parallel download, the file to be retrieved is split into N chunks and
each chunk is downloaded concurrently by one of M threads in a first-come,
first-served fashion. If the chunksize is 0, then parallel downloads are disabled. If
M > N, then the actual number of threads used will be reduced to N. The number of
threads can be specified using the --parallel argument. If --parallel is 1, then only
a single thread is used. The default value is 4. There is no maximum number of
threads, but it is likely that the link will be saturated by 4 to 8 threads.

lsup
The lsup subcommand lists active multipart uploads. The URL specified should point to
a bucket. This command is only valid if the site supports multipart uploads. The
output of this command is a list of keys and upload IDs.

This subcommand is used with rmup to help recover from failures of multipart uploads.

rmup
The rmup subcommand cancels and active upload. The URL specified should point to a
bucket, and UPLOAD is the long, complicated upload ID shown by the lsup subcommand.

This subcommand is used with lsup to recover from failures of multipart uploads.

cp
The cp subcommand copies keys on the server. Keys cannot be copied between accounts.

URL FORMAT

All URLs for objects stored in S3 should be specified in the following format:

s3[s]://USER@SITE[/BUCKET[/KEY]]

The protocol part can be s3:// or s3s://. If s3s:// is used, then pegasus-s3 will force
the connection to use SSL and override the setting in the configuration file. If s3:// is
used, then whether the connection uses SSL or not is determined by the value of the
endpoint variable in the configuration for the site.

The USER@SITE part is required, but the BUCKET and KEY parts may be optional depending on
the context.

The USER@SITE portion is referred to as the “identity”, and the SITE portion is referred
to as the “site”. Both the identity and the site are looked up in the configuration file
(see CONFIGURATION) to determine the parameters to use when establishing a connection to
the service. The site portion is used to find the host and port, whether to use SSL, and
other things. The identity portion is used to determine which authentication tokens to
use. This format is designed to enable users to easily use multiple services with multiple
authentication tokens. Note that neither the USER nor the SITE portion of the URL have any
meaning outside of pegasus-s3. They do not refer to real usernames or hostnames, but are
rather handles used to look up configuration values in the configuration file.

The BUCKET portion of the URL is the part between the 3rd and 4th slashes. Buckets are
part of a global namespace that is shared with other users of the storage service. As
such, they should be unique.

The KEY portion of the URL is anything after the 4th slash. Keys can include slashes, but
S3-like storage services do not have the concept of a directory like regular file systems.
Instead, keys are treated like opaque identifiers for individual objects. So, for example,
the keys a/b and a/c have a common prefix, but cannot be said to be in the same directory.

Some example URLs are:

s3://ewa@amazon
s3://juve@skynet/gideon.isi.edu
s3://juve@magellan/pegasus-images/centos-5.5-x86_64-20101101.part.1
s3s://ewa@amazon/pegasus-images/data.tar.gz

CONFIGURATION

Each user should specify a configuration file that pegasus-s3 will use to look up
connection parameters and authentication tokens.

Search Path
This client will look in the following locations, in order, to locate the user’s
configuration file:

1. The -C/--conf argument

2. The S3CFG environment variable

3. $HOME/.pegasus/s3cfg

4. $HOME/.s3cfg

If it does not find the configuration file in one of these locations it will fail with an
error. The $HOME/.s3cfg location is only supported for backward-compatibility.
$HOME/.pegasus/s3cfg should be used instead.

Configuration File Format
The configuration file is in INI format and contains two types of entries.

The first type of entry is a site entry, which specifies the configuration for a storage
service. This entry specifies the service endpoint that pegasus-s3 should connect to for
the site, and some optional features that the site may support. Here is an example of a
site entry for Amazon S3:

[amazon]
endpoint = http://s3.amazonaws.com/

The other type of entry is an identity entry, which specifies the authentication
information for a user at a particular site. Here is an example of an identity entry:

[pegasus@amazon]
access_key = 90c4143642cb097c88fe2ec66ce4ad4e
secret_key = a0e3840e5baee6abb08be68e81674dca

It is important to note that user names and site names used are only logical—they do not
correspond to actual hostnames or usernames, but are simply used as a convenient way to
refer to the services and identities used by the client.

The configuration file should be saved with limited permissions. Only the owner of the
file should be able to read from it and write to it (i.e. it should have permissions of
0600 or 0400). If the file has more liberal permissions, then pegasus-s3 will fail with an
error message. The purpose of this is to prevent the authentication tokens stored in the
configuration file from being accessed by other users.

Configuration Variables
endpoint (site)
The URL of the web service endpoint. If the URL begins with https, then SSL will be
used.

max_object_size (site)
The maximum size of an object in GB (default: 5GB)

multipart_uploads (site)
Does the service support multipart uploads (True/False, default: False)

ranged_downloads (site)
Does the service support ranged downloads? (True/False, default: False)

access_key (identity)
The access key for the identity

secret_key (identity)
The secret key for the identity

Example Configuration
This is an example configuration that specifies a two sites (amazon and magellan) and
three identities (pegasus@amazon,juve@magellan, and voeckler@magellan). For the amazon
site the maximum object size is 5TB, and the site supports both multipart uploads and
ranged downloads, so both uploads and downloads can be done in parallel.

[amazon]
endpoint = https://s3.amazonaws.com/
max_object_size = 5120
multipart_uploads = True
ranged_downloads = True

[pegasus@amazon]
access_key = 90c4143642cb097c88fe2ec66ce4ad4e
secret_key = a0e3840e5baee6abb08be68e81674dca

[magellan]
# NERSC Magellan is a Eucalyptus site. It doesn't support multipart uploads,
# or ranged downloads (the defaults), and the maximum object size is 5GB
# (also the default)
endpoint = https://128.55.69.235:8773/services/Walrus

[juve@magellan]
access_key = quwefahsdpfwlkewqjsdoijldsdf
secret_key = asdfa9wejalsdjfljasldjfasdfa

[voeckler@magellan]
# Each site can have multiple associated identities
access_key = asdkfaweasdfbaeiwhkjfbaqwhei
secret_key = asdhfuinakwjelfuhalsdflahsdl

EXAMPLE

List all buckets owned by identity user@amazon:

$ pegasus-s3 ls s3://user@amazon

List the contents of bucket bar for identity user@amazon:

$ pegasus-s3 ls s3://user@amazon/bar

List all objects in bucket bar that start with hello:

$ pegasus-s3 ls s3://user@amazon/bar/hello

Create a bucket called mybucket for identity user@amazon:

$ pegasus-s3 mkdir s3://user@amazon/mybucket

Delete a bucket called mybucket:

$ pegasus-s3 rmdir s3://user@amazon/mybucket

Upload a file foo to bucket bar:

$ pegasus-s3 putfoo s3://user@amazon/bar/foo

Download an object foo in bucket bar:

$ pegasus-s3 get s3://user@amazon/bar/foo foo

Upload a file in parallel with 4 threads and 100MB chunks:

$ pegasus-s3 put --parallel 4 --chunksize 100 foo s3://user@amazon/bar/foo

Download an object in parallel with 4 threads and 100MB chunks:

$ pegasus-s3 get --parallel 4 --chunksize 100 s3://user@amazon/bar/foo foo

List all partial uploads for bucket bar:

$ pegasus-s3 lsup s3://user@amazon/bar

Remove all partial uploads for bucket bar:

$ pegasus-s3 rmup --all s3://user@amazon/bar

RETURN VALUE

pegasus-s3 returns a zero exist status if the operation is successful. A non-zero exit
status is returned in case of failure.

Use pegasus-s3 online using onworks.net services