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Using Allas with Python

CSC's instructions for Installing OpenStack and other required Python libraries.

Download the OpenStack RC File v3 as instructed in the last section Configure your terminal environment for OpenStack.

The Python pip libraries required in the examples:
python-keystoneclient and python-swiftclient.

This page includes Python scripts for the following operations:

Function
Create a connection to server
Create a bucket
Upload an object
List buckets and objects
Download an object
Remove buckets and objects

Create a connection

This Python script creates a connection to the server: 

from keystoneauth1 import session
from keystoneauth1.identity import v3
import os
import swiftclient
from swiftclient.multithreading import OutputManager
from swiftclient.service import SwiftError, SwiftService, SwiftUploadObject


_authurl = os.environ['OS_AUTH_URL']
_auth_version = os.environ['OS_IDENTITY_API_VERSION']
_user = os.environ['OS_USERNAME']
_key = os.environ['OS_PASSWORD']
_os_options = {
    'user_domain_name': os.environ['OS_USER_DOMAIN_NAME'],
    'project_domain_name': os.environ['OS_USER_DOMAIN_NAME'],
    'project_name': os.environ['OS_PROJECT_NAME']
}

conn = swiftclient.Connection(
    authurl=_authurl,
    user=_user,
    key=_key,
    os_options=_os_options,
    auth_version=_auth_version
)

Alternatively, you can enter the information directly in the script from the downloaded RC file:

import swiftclient

_authurl = 'https://pouta.csc.fi:5001/v3'
_auth_version = '3'
_user = 'John'
_key = 'John1234'
_os_options = {
    'user_domain_name': 'Default',
    'project_domain_name': 'Default',
    'project_name': 'project_123456'
}

conn = swiftclient.Connection(
    authurl=_authurl,
    user=_user,
    key=_key,
    os_options=_os_options,
    auth_version=_auth_version
)

In the above example:
OS_AUTH_URL = _authurl = https://pouta.csc.fi:5001/v3
OS_IDENTITY_API_VERSION = _auth_version = 3
OS_USERNAME = _user = John
OS_PASSWORD = _key = John1234
OS_PROJECT_NAME = project_name = project_123456

Further information of the Keystone authentication:
https://docs.openstack.org/python-swiftclient/newton/client-api.html

Create a bucket

Create a new bucket using the following script:

bucket_name='snakebucket'
conn.put_container(bucket_name)

Upload an object

Upload a small file called my_snake.txt to the bucket snakebucket:

object_name='my_snake.txt'
with open(object_name, 'r') as f:
    conn.put_object(bucket_name, object_name,
                    contents=f.read(),
                    content_type='text/plain')
The upload process above works only for files that are smaller than 5 GB. In the case of larger files, you should use SwiftService.

object_list = [ 'my_snake.txt' ]
# limit upload threads to 4
opts = {'object_uu_threads': 4}

with SwiftService(options=opts) as swift:
    try:
        for r in swift.upload(bucket_name, object_list, { 'segment_size': 5000000000, }):
            if r['success']:
                if 'object' in r:
                    print(r['object'])
                elif 'for_object' in r:
                    print(
                        '%s segment %s' % (r['for_object'],
                            r['segment_index'])
                         )
            else:
                print(r)

    except SwiftError as e:
        print(e.value)

List buckets and objects

List all buckets belonging to a project: 

resp_headers, containers = conn.get_account()

for container in containers:
   print(container)

And all objects belonging to a bucket: 

for info in conn.get_container('snakebucket')[1]:
    print('{0}\t{1}\t{2}'.format(info['name'], info['bytes'], info['last_modified']))

Download an object

Download an object: 

my_obj = conn.get_object(bucket_name, object_name)[1]
with open('new_name_for_file.txt', 'w') as f:
    f.write(my_obj)

Please note: If you get the error 

TypeError: write() argument must be str, not bytes
open the file in the binary mode 
with open('new_name_for_file.txt', 'bw') as f:
    f.write(my_obj)
instead of the text mode.

Remove buckets and objects

Delete a bucket: 

conn.delete_container(bucket_name)

Note: Only empty buckets can be removed.

Remove an object: 

conn.delete_object(bucket_name, 'my_snake.txt')

Last update: September 21, 2022