Tutorial: Python

In this tutorial you will learn to setup your environment, create a volume, then take its snapshot, create cloud credentials, and create a backup of the volume.

The sources for this tutorial are available in the examples/python directory in the repo for this website.

If you would like to try this tutorial on the web, check out our Katacoda Scenario: OpenStorage SDK Python Client Tutorial.

Setting up your environment

To setup your environment, you will need to copy openstorage and google directories from openstorage-sdk-clients/sdk/python to your project.

NOTE: We will be adding this package to pip in future releases.

We will now use virutalenv to install a python local environment:

$ virtualenv sdk
$ source sdk/bin/activate
$ pip install grpcio grpcio-tools

You will now have access to the OpenStorage SDK Python client which was generated from the protobuf file api.proto.

With the mock-sdk-server running, the following steps will provide an introduction to programming with the OpenStorage SDK.

Import dependencies

For most of the examples below, you will need the following import's.

import grpc
from openstorage import api_pb2
from openstorage import api_pb2_grpc

Creating a connection

To use any of the gRPC functions, you must first create a connection with the OpenStorage SDK server:

# Cluster connection
channel = grpc.insecure_channel('localhost:9100')

NOTE: Notice the call grpc.insecure_channel(). The mock-sdk-server supports HTTPS and authentication starting at v0.38.0. See Tutorial for more information.

Cluster operations

Now that we have made a connection, we can use the channel object to create clients for each of the services we would like to use. Let's use the OpenStorageCluster service to print the id of the cluster:

try:
    # Cluster connection
    clusters = api_pb2_grpc.OpenStorageClusterStub(channel)
    ic_resp = clusters.InspectCurrent(api_pb2.SdkClusterInspectCurrentRequest())
    print('Connected to {0} with status {1}'.format(
        ic_resp.cluster.id,
        api_pb2.Status.Name(ic_resp.cluster.status)
    ))
except grpc.RpcError as e:
    print('Failed: args={0} msg={1}'.format(e.args, e.message))

Notice the except above. As mentioned in the Architecture all errors are encoded using the standard gRPC status. To gain access to the error code and its message you must use except grpc.RpcError as e which decodes the error value and the message.

Volume Operations

Now that we have connected to the cluster, let's go ahead and create a volume of size 100Gi:

    volumes = api_pb2_grpc.OpenStorageVolumeStub(channel)
    v_resp = volumes.Create(api_pb2.SdkVolumeCreateRequest(
        name="myvol",
        spec=api_pb2.VolumeSpec(
            size=100*1024*1024*1024,
            ha_level=3,
        )
    ))
    print('Volume id is {0}'.format(v_resp.volume_id))

Notice the value of name provided above. This value is important since it allows for the function to be idempotent. In other words, this function will always return the same volume id for the volume of same name.

You can now create a snapshot of this volume:

    # Create a snapshot
    snap = volumes.SnapshotCreate(api_pb2.SdkVolumeSnapshotCreateRequest(
        volume_id=v_resp.volume_id,
        name="mysnap"
    ))
    print('Snapshot created with id {0}'.format(snap.snapshot_id))

Backup

In this section we will be making a backup of our volume to a cloud provider. To do this, we must first create a set of credentials which will enable the storage system to save the backup in the cloud.

    # Create a credentials
    creds = api_pb2_grpc.OpenStorageCredentialsStub(channel)
    cred_resp = creds.Create(api_pb2.SdkCredentialCreateRequest(
        name='aws',
        aws_credential=api_pb2.SdkAwsCredentialRequest(
            access_key='dummy',
            secret_key='dummy',
            endpoint='dummy',
            region='dummy'
        )
    ))
    print('Credential id is {0}'.format(cred_resp.credential_id))

Notice above the api_pb2.SdkCredentialCreateRequest. This struct in protobuf uses oneof. Oneof states that one of these types will be used. In SdkCredentialCreateRequest, only aws_credential is set, showing the server which type of credentials are being registered.

The backup of the volume can now be started with the newly acquired credential id:

    # Create backup
    backups = api_pb2_grpc.OpenStorageCloudBackupStub(channel)
    backup_resp = backups.Create(api_pb2.SdkCloudBackupCreateRequest(
        volume_id=v_resp.volume_id,
        credential_id=cred_resp.credential_id,
        full=False
    ))

This request will not block while the backup is running. Instead you should call OpenStorageCloudBackup.Status() to get information about the backup:

    status_resp = backups.Status(api_pb2.SdkCloudBackupStatusRequest(
        volume_id=v_resp.volume_id
    ))
    backup_status = status_resp.statuses[v_resp.volume_id]
    print('Status of the backup is {0}'.format(
        api_pb2.SdkCloudBackupStatusType.Name(backup_status.status)
    ))

Lastly, once the backup is complete, we can get a history of this and any other backups we have created from our volume:

    # Show history
    history = backups.History(api_pb2.SdkCloudBackupHistoryRequest(
        src_volume_id=v_resp.volume_id
    ))
    print('Backup history for volume {0}'.format(v_resp.volume_id))
    for item in history.history_list:
        print('Time:{0} Status:{1}'.format(
            item.timestamp.ToJsonString(),
            api_pb2.SdkCloudBackupStatusType.Name(item.status)
        ))

Example output

Below is an example output run of this tutorial:

Conntected to portworx with status STATUS_OK
Volume id is 9b64012f-db53-4a7b-8393-94b3d1ba0b02
Snapshot created with id 26a7262c-3eec-4352-a0be-3710d25f8335
Credential id is 716ed48f-f089-453d-ba07-7072eacd2ba0
Status of the backup is SdkCloudBackupStatusTypeDone
Backup history for volume 9b64012f-db53-4a7b-8393-94b3d1ba0b02
Time:2018-07-18T02:04:53.278579951Z Status:SdkCloudBackupStatusTypeDone

Next

As you can see from the above, working with OpenStorage SDK is quite easy, fun, and powerful. Please refer to the API Reference for a complete list of services.

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