NetApp ONTAP

The Python client library is a package you can use when writing scripts to access the ONTAP REST API. It provides support for several underlying services, including connection management, asynchronous request processing, and exception handling. By using the Python client library, you can quickly develop robust code to support the automation of your ONTAP deployments.

Getting started

The Python client library is available as the package netapp_ontap at the Python Package Index (PyPi) web site at https://pypi.org/project/netapp-ontap

Software requirements

Before installing the Python client library, you must make sure the following packages are installed on your system:

1. python 3.5 or later
2. requests 2.21.0 or later
3. marshmallow between 3.0.0rc5 and 3.0.0rc7

Installing and importing the package

You must install the package using the pip utility:

pip install netapp-ontap

After installing the package, you can import the objects you need into your application:

from netapp_ontap.resources import Volume, Snapshot

Creating an object

You can create an object in several different ways. Here are three examples of creating an equivalent netapp_ontap.resources.volume object.

from netapp_ontap.resources import Volume

# Example 1 - keyword arguments
volume = Volume(name='vol1', svm={'name': 'vs1'}, aggregates=[{'name': 'aggr1'}])

# Example 2 - dict as keyword arguments
data = {
    'name': 'vol1',
    'svm': {'name': 'vs1'},
    'aggregates': [{'name': 'aggr1'}],
}
volume = Volume(**data)

# Example 3 - using the from_dict() method
volume = Volume.from_dict({
    'name': 'vol1',
    'svm': {'name': 'vs1'},
    'aggregates': [{'name': 'aggr1'}],
})

Performing actions on an object

After you create an object, you can perform actions on the object based on the purpose and design of your application. The example below illustrates how to create a new volume and then take a snapshot.

Note that when using the library, in all cases you must first establish a connection to the management LIF of the ONTAP system using the netapp_ontap.host_connection.HostConnection object. In the example below, the connection is created and then set as the global default. This means that all objects and the associated actions reuse this same connection. See Host connections for more information.

from netapp_ontap import config
from netapp_ontap.host_connection import HostConnection
from netapp_ontap.resources import Volume, Snapshot

config.CONNECTION = HostConnection('myhost.mycompany.com', 'username', 'password')

volume = Volume(name='vol1', svm={'name': 'vs1'}, aggregates=[{'name': 'aggr1'}])
volume.post()
snapshot = Snapshot.from_dict({
    'name': '%s_snapshot' % volume.name,
    'comment': 'A snapshot of %s' % volume.name,
    'volume': volume.to_dict(),
})
snapshot.post()

Host connections

The netapp_ontap.host_connection.HostConnection object allows a client application to store credentials once and reuse them for each subsequent operation. You can do this in any of the following ways:

• Use the connection object as a context manager with the with keyword.

• Call the function set_connection() on a specific resource so the connection is used for all actions on the resource.

• Set the config.CONNECTION variable to establish a single connection instance for all operations within the scope of that block. This allows you to connect to ONTAP once and use the same connection everywhere, instead of providing credentials every time you make a request.

Note that you can call get_connection() to get the connection used by an object and use it for subsequent operations.

By default, every operation attempts to verify the SSL certificate for the connection. If a certificate cannot be verified, the SSLError exception is thrown. You can disable this verification by setting verify to false when creating the netapp_ontap.host_connection.HostConnection instance.

Asynchronous processing and jobs

All POST, PATCH, and DELETE requests that can take more than two seconds to complete are designed to run asynchronously as non-blocking operations. These operations are executed as background jobs at the ONTAP cluster. The HTTP response generated by an asynchronous request always contains a link to the associated job object. By default, an asynchronous request automatically polls the job using the unique job identifier in the link. Control is returned to your script when a terminal state is reached (success or failure) or the configured timeout value expires. However, you can override this behavior by setting the poll value to false when calling the function, causing control to return before the job completes. Forcing an immediate return can be useful when a job might take a long time to complete and you want to continute execution of the script.

Responses

A request always returns a netapp_ontap.response.NetAppResponse object which contains the details of the HTTP response. It contains information such as whether the response was an error or a job. Refer to netapp_ontap.response.NetAppResponse for further information on how to check the details of the response.

Exception handling

By default, an exception is returned if a request returns an HTTP status code of 400 or greater. The exception object, which is of type netapp_ontap.error.NetAppRestError, holds the HTTP response object so that the exception can be handled in the client code. If you wish not to raise exceptions, you can set raise_api_errors to False. In this case, it is up to the client to check the HTTP response from the netapp_ontap.response.NetAppResponse object and handle any errors. Refer to netapp_ontap.error.NetAppRestError for further information.

# Set RAISE_API_ERRORS to False and check the HTTP response.
config.RAISE_API_ERRORS = False
response = Svm.find(name = "nonexistent_vs)
assert "entry doesn't exist" in response.http_response.text

Additional considerations

In most cases, the objects and actions in the library can be mapped directly to equivalent cURL commands run against the ONTAP REST interface. However, there are a few exceptions you should be aware of.

Property names

If a property of a resource is named the same as one of the Python reserved names, the name is transposed when accessing the member of the resource. For example, if there is a resource named "Foo" that has a property defined in the API named "class", the property name would instead be "class_" when using the library. For example:

from netapp_ontap.resources import Foo

foo = Foo()
foo.class_ = "high"

Compatibility

The version assigned to the library consists of the major ONTAP release it is generated from and a minor version for the library within that release. The minor version allows the library to be updated within the same ONTAP release. For example, valid versions for the library associated with ONTAP 9.6 include 9.6.1, 9.6.2, and so on.

Client libraries that have the same major version as ONTAP are completely compatible. For example, the libraries netapp-ontap-9.6.1 and netapp-ontap-9.6.4 are fully compatible with both ONTAP 9.6 and ONTAP 9.6P1.

A client library with a major version that does not match the ONTAP release can still be used, however it will not be fully compatible with the REST API. For example, the library netapp-ontap-9.6.4 is only partially compatible with ONTAP 9.7. In these cases, the library may encounter unknown fields or APIs. When this occurs, the library will ignore unknown fields, return an error, or raise a runtime exception.

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