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.. _guide_migration_s3:
Amazon S3
=========
Boto 2.x contains a number of customizations to make working with Amazon S3 buckets and keys easy. Boto 3 exposes these same objects through its resources interface in a unified and consistent way.
Creating the Connection
-----------------------
Boto 3 has both low-level clients and higher-level resources. For Amazon S3, the higher-level resources are the most similar to Boto 2.x's ``s3`` module::
# Boto 2.x
import boto
s3_connection = boto.connect_s3()
# Boto 3
import boto3
s3 = boto3.resource('s3')
Creating a Bucket
-----------------
Creating a bucket in Boto 2 and Boto 3 is very similar, except that in Boto 3 all action parameters must be passed via keyword arguments and a bucket configuration must be specified manually::
# Boto 2.x
s3_connection.create_bucket('mybucket')
s3_connection.create_bucket('mybucket', location=Location.USWest)
# Boto 3
s3.create_bucket(Bucket='mybucket')
s3.create_bucket(Bucket='mybucket', CreateBucketConfiguration={
'LocationConstraint': 'us-west-1'})
Storing Data
------------
Storing data from a file, stream, or string is easy::
# Boto 2.x
from boto.s3.key import Key
key = Key('hello.txt')
key.set_contents_from_file('/tmp/hello.txt')
# Boto 3
s3.Key('mybucket', 'hello.txt').put(Body=open('/tmp/hello.txt'))
Accessing a Bucket
------------------
Getting a bucket is easy with Boto 3's resources, however these do not automatically validate whether a bucket exists::
# Boto 2.x
bucket = s3_connection.get_bucket('mybucket', validate=False)
exists = s3_connection.lookup('mybucket')
# Boto 3
bucket = s3.Bucket('mybucket')
exists = True
try:
s3.meta.client.head_bucket(Bucket='mybucket')
except ClientError as e:
# If a client error is thrown, then check that it was a 404 error.
# If it was a 404 error, then the bucket does not exist.
error_code = int(e.response['Error']['Code'])
if error_code == 404:
exists = False
Deleting a Bucket
-----------------
All of the keys in a bucket must be deleted before the bucket itself can be deleted::
# Boto 2.x
for key in bucket:
key.delete()
bucket.delete()
# Boto 3
for key in bucket.objects.all():
key.delete()
bucket.delete()
Iteration of Buckets and Keys
-----------------------------
Bucket and key objects are no longer iterable, but now provide collection attributes which can be iterated::
# Boto 2.x
for bucket in s3_connection:
for key in bucket:
print(key.name)
# Boto 3
for bucket in s3.buckets.all():
for key in bucket.objects.all():
print(key.name)
Access Controls
---------------
Getting and setting canned access control values in Boto 3 operates on an ``ACL`` resource object::
# Boto 2.x
bucket.set_acl('public-read')
key.set_acl('public-read')
# Boto 3
bucket.Acl().put(ACL='public-read')
obj.put(ACL='public-read')
It's also possible to retrieve the policy grant information::
# Boto 2.x
acp = bucket.get_acl()
for grant in acp.acl.grants:
print(grant.display_name, grant.permission)
# Boto 3
acl = bucket.Acl()
for grant in acl.grants:
print(grant['DisplayName'], grant['Permission'])
Boto 3 lacks the grant shortcut methods present in Boto 2.x, but it is still fairly simple to add grantees::
# Boto 2.x
bucket.add_email_grant('READ', 'user@domain.tld')
# Boto 3
bucket.Acl.put(GrantRead='emailAddress=user@domain.tld')
Key Metadata
------------
It's possible to set arbitrary metadata on keys::
# Boto 2.x
key.set_metadata('meta1', 'This is my metadata value')
print(key.get_metadata('meta1'))
# Boto 3
key.put(Metadata={'meta1': 'This is my metadata value'})
print(key.metadata['meta1'])
Managing CORS Configuration
---------------------------
Allows you to manage the cross-origin resource sharing configuration for S3 buckets::
# Boto 2.x
cors = bucket.get_cors()
config = CORSConfiguration()
config.add_rule('GET', '*')
bucket.set_cors(config)
bucket.delete_cors()
# Boto 3
cors = bucket.Cors()
config = {
'CORSRules': [
{
'AllowedMethods': ['GET'],
'AllowedOrigins': ['*']
}
]
}
cors.put(CORSConfiguration=config)
cors.delete()
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