The Swift client

The Python Swift client is a command line tool for using object storage systems such as Allas. If you use Allas on Puhti or Mahti, all required packages and software are already installed.

module load allas

Open a connection to Allas:

allas-conf

The allas-conf command above asks for your CSC password (the same that you use to login to CSC servers). It lists your projects in Allas and asks you to define the project that will be used. allas-conf generates and authenticates the connection to the selected project in Allas. The authentication information is stored in the shell variables OS_AUTH_TOKEN and OS_STORAGE_URL that are valid for up to eight hours. However, you can refresh the authentication at any time by running allas-conf again. The environment variables are available only for that login session. If you open another session, you need to authenticate again to access Allas.

This chapter includes instructions for the following operations:

Swift command	Function
post	Create a bucket
upload	Upload an object
list	List objects and buckets
download	Download objects and buckets
copy	Move object
delete	Remove objects or bucket
download --all	Download whole project
delete --all	Remove whole project
md5sum	Get the checksum
stat	View metadata
stat --meta	Add metadata
tempurl	Create a temporary URL
post -r, -w, --read-acl	Manage access rights
upload --use-slo	Upload files larger than 5 GB

You can also install and use Swift outside the CSC computing environment. Make sure that your Swift version is not outdated, since the older Swift versions might not work with Allas.

Create buckets and upload objects

Create a new empty bucket:

swift post <new_bucket_name>

Create a new bucket and add a file to it:

swift upload <new_bucket_name> <file_name>

Add a file to an existing bucket:

swift upload <old_bucket_name> <file_name>

Note: This might trigger the warning "409 Conflict: BucketAlreadyExists", but that does not necessarily mean that the upload has failed. If the next line displays the file name, the file was successfully uploaded to the existing bucket.

$ swift upload my_fishbucket my_fish.jpg
Warning: failed to create container 'my_fishbucket': 409 Conflict: BucketAlreadyExists
my_fish.jpg

List objects and buckets

List all buckets belonging to a project:

$ swift list
my_fishbucket
my_bigfishes

List the content of a bucket:

$ swift list my_fishbucket
my_fish.jpg
salmon.jpg
bass.png

Download objects and buckets

Download an object:

swift download <bucket_name> <file_name>

If you want to rename the object as you download it, you can include -o new_name in the end of the command:

swift download <bucket_name> <file_name> -o <new_name>

Download an entire bucket:

swift download <bucket_name>

Move objects

You can copy data from one bucket to another using the command swift copy. The command below copies file.txt from bucket1 to bucket2.

swift copy --destination /bucket2 bucket1 file.txt

Note: If there is no bucket called bucket2, Swift creates a new bucket with that name. However, even if there is a bucket called bucket2, Swift claims that it created a new one, even though it simply copied the file to the existing bucket:

$ swift copy --destination /other_bucket my_bigfishes bigfish.jpg
created container other_bucket
my_bigfishes/bigfish.jpg copied to /other_bucket/bigfish.jpg
$ swift list other_bucket
bigfish.jpg
other_file.txt

Rename a file while copying it:

$ swift copy --destination /new_bucket/newname.jpg my_fishbucket my_fish.jpg
created container new_bucket
my_fishbucket/my_fish.jpg copied to /new_bucket/newname.jpg

For further information about the command swift copy, see the OpenStack documentation.

Remove objects and buckets

Remove objects and buckets using the command swift delete:

swift delete <bucket_name> <object_name>

For example:

$ swift delete my_fishbucket useless_fish.jpg
useless_fish.jpg

Unlike with the web client and s3cmd, with Swift, you can delete an entire bucket at once:

swift delete <my_old_bucket>

For example:

$ swift delete old_fishbucket
old_fish.png
useless_salmon.jpg
too_tiny_bass.jpg
$ swift list old_fishbucket
Container u'old_fishbucket' not found

Please note: This deletes the bucket permanently, and the data is lost. Before using this command, make sure you do not need the data anymore or that you have a copy of the data.

Download or delete projects

Download the entire project:

swift download --all

Delete the entire project:

swift delete --all

Please note: Be careful with this command since it deletes the entire content of the project. Before using this command, make sure you do not need the data anymore or that you have a copy of the data.

Pseudo folders and checksums

In case you want to observe whether an object has changed, use checksum with the command md5sum.

Pseudo folders can be handled by adding the name of the pseudo folder in front of the file name: my_pseudo_folder_name/my_file

Create a pseudo folder named pictures in the bucket my_bigfishes and add the object bass.png to it:

$ swift upload my_bigfishes/pictures bass.png
pictures/bass.png

The example below uploads a file called salmon.jpg to the pseudo folder called fishes inside the bucket my_fishbucket. The file is then downloaded.

$ md5sum salmon.jpg
22e44aa2b856e4df892b43c63d15138a  salmon.jpg
$ swift upload my_fishbucket/fishes salmon.jpg
fishes/salmon.jpg
$ swift list my_fishbucket
fishes/salmon.jpg
my_fish.jpg
$ swift download my_fishbucket fishes/salmon.jpg -o my_renamed_salmon.jpg
fishes/salmon.jpg [auth 0.664s, headers 0.925s, total 0.969s, 3.605 MB/s]
$ md5sum my_renamed_salmon.jpg
22e44aa2b856e4df892b43c63d15138a  my_renamed_salmon.jpg

Note: The checksums of the object salmon.jpg and the renamed version my_renamed_salmon.jpg are the same since the file is the same and has not changed.

Managing metadata

Define metadata for an object:

swift post my_fishbucket my_fish.jpg --meta foo:bar

Display details about a bucket:

$ swift stat my_fishbucket
                      Account: AUTH_$PROJECT_UUID
                    Container: my_fishbucket
                      Objects: 4
                        Bytes: 2162342
                     Read ACL:
                    Write ACL:
                      Sync To:
                     Sync Key:
                Accept-Ranges: bytes
                   X-Trans-Id: txUUID-cpouta-production-kaj
             X-Storage-Policy: default-placement
X-Container-Bytes-Used-Actual: 1167360
                  X-Timestamp: 1516776076.95812

Set a bucket as read-only to the world (make the content visible at the URL: a3s.fi/bucket_name/object_name) instead of the default (private to the project):

swift post my_fishbucket --read-acl ".r:*"

Find more information about access management in the section Giving another project read and write access to a bucket.

More details about a file:

$ swift stat my_fishbucket fishes/salmon.jpg
         Account: AUTH_$PROJECT_ID
       Container: my_fishbucket
          Object: fishes/salmon.jpg
    Content Type: image/jpeg
  Content Length: 63220
   Last Modified: Wed, 24 Jan 2018 10:17:03 GMT
            ETag: a38f8db198e3fea43c83c465ffb0283b
Meta S3Cmd-Attrs: atime:1516788402/ctime:1513681753/gid:$LOCALGID/gname:$LOCALGROUP/md5:a38f8db198e3fea43c83c465ffb0283b/mode:33188/mtime:1513681747/uid:$LOCALUID/uname:$LOCALUSER
   Accept-Ranges: bytes
     X-Timestamp: 1516789023.84380
      X-Trans-Id: tx0000000000000000001d6-q-q-cpouta-production-kaj

Note that the above file was uploaded with the s3cmd client, and therefore there is the additional metadata S3Cmd-Attrs compared to a file uploaded with Swift or S3. ETag is the hash when viewing the file details in the Pouta dashboard.

Giving another project read and write access to a bucket

Give the project project1 read rights to the bucket my_fishbucket:

swift post my_fishbucket -r "project1:*"

Write access can be given similarly by replacing -r (read) with -w (write):

swift post my_fishbucket -w "project1:*"

The character * after the project name defines that all project members in the project gain the rights.

Alternatively, you can give read and write access only to certain members of another project:

swift post my_fishbucket -r "project2:member1"
swift post my_fishbucket -w \
   "project3:member1,project3:member2,project5:member1,project6:*"

Please note: If you have granted access for specific projects, making the shared project public and private again will remove any previous access permissions.

In case you allow -w access for another project, the members of the other project can upload files to your bucket and remove your files. However, you do not have access to the uploaded files until either you or the sender shares the bucket with your project:

swift post <your_bucket_name> -r "your_project:*"

For example:

swift post my_fishbucket -r "project_1234:*,project_4567:*"

Alternatively, you can set the project public and then access the file.

Files larger than 5 GB

Swift has a single-object size limit of 5 GiB. In order to upload files larger than this, you must create a large object that consists of smaller segments. To achieve this, you can use Swift to upload a so-called Static Large Object (SLO).

Try to upload a large file:

$ md5sum /tmp/6GB.zero
9e6a77a2d5650b2e2a710a08e9e61a81  /tmp/6GB.zero
$ stat /tmp/6GB.zero
File: '/tmp/6GB.zero'
Size: 6424625152      Blocks: 12548104   IO Block: 4096   regular file
...
$ swift upload my_bigfishes /tmp/6GB.zero
Object PUT failed: https://a3s.fi:443/swift/v1/my_bigfishes/tmp/6GB.zero 400 Bad Request   EntityTooLarge

It fails with the message EntityTooLarge, so instead:

$ swift upload my_bigfishes --use-slo --segment-size 1G /tmp/6GB.zero
tmp/6GB.zero segment 3
tmp/6GB.zero segment 5
tmp/6GB.zero segment 1
tmp/6GB.zero segment 0
tmp/6GB.zero segment 4
tmp/6GB.zero segment 2
tmp/6GB.zero

This creates a new bucket:

$ swift list |grep my_bigfishes
my_bigfishes
my_bigfishes_segments

In this case the target bucket (my_bigfishes) contains just a front object that contains information what segments, stored in the segments bucket (my_bigfishes_segments) make the stored file. Operations performed to the front object are automatically reflected to the segments. Normally users don't need to operate with the segments buckets at all and objects inside these buckets should not be deleted or modified.

Download the entire 6GB.zero:

$ swift download my_bigfishes tmp/6GB.zero -o /tmp/6GB.zero
tmp/6GB.zero [auth 0.594s, headers 0.881s, total 74.467s, 86.969 MB/s]
$ md5sum 6GB.zero
9e6a77a2d5650b2e2a710a08e9e61a81  6GB.zero

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Last update: October 5, 2020

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