Function Cookbook

updated: 2018-08-29 05:10

Function Cookbook¶

Introduction¶

Qinling function lets you execute your code in a serverless environment without having to first create a VM or container. This cookbook contains several examples for how to create functions in Qinling.

Examples¶

Create python function with libraries in a package¶

This guide describes how to create a python function with libraries in a package and how to invoke the function in a Python runtime(the steps assume there is already a Python 2.7 runtime available in the deployment).

The function resizes an image which stores in Swift and uploads the resized image to a new container with a same object name. For the function to work, a python library called Pillow needs to be installed together with the function code, the python-swiftclient doesn’t need to be installed because Qinling supports it as a built-in library in Qinling’s default Python 2.7 runtime implementation.

The function needs two positional parameters:

container_name: The container name in Swift that the original image file is stored in.
object_name: The object name in the container.

There is no output for the function itself, but you can check the function execution log to see the whole process.

Note

The following process has been tested in a Devstack environment in which Swift is also installed.

Create a directory, for example ~/qinling_test
```
$ mkdir ~/qinling_test
```

Write a custom python code for resizing an image at the root level of the directory created above.

$ cat <<EOF > ~/qinling_test/resize_image.py
import os

from PIL import Image
import swiftclient
from swiftclient.exceptions import ClientException


def resize_image(image_path, resized_path):
    with Image.open(image_path) as image:
        image.thumbnail(tuple(x / 4 for x in image.size))
        image.save(resized_path)


def main(context, container_name, object_name):
    conn = swiftclient.Connection(
        session=context['os_session'],
        os_options={'region_name': 'RegionOne'},
    )

    # Download original image
    image_path = os.path.abspath('./%s' % object_name)
    _, obj_contents = conn.get_object(container_name, object_name)
    with open(image_path, 'w') as local:
        local.write(obj_contents)

    print('Downloaded object %s from container %s' % (object_name, container_name))

    thumb_path = os.path.abspath('./%s_resized.png' % object_name)
    resize_image(image_path, thumb_path)

    print('Resized.')

    # Create new container if needed
    new_container_name = '%s_resized' % container_name
    try:
        conn.head_container(new_container_name)
    except ClientException:
        conn.put_container(new_container_name)
        print("New container %s created." % new_container_name)

    # Upload resized image
    with open(thumb_path, 'r') as new_local:
        conn.put_object(
            new_container_name,
            object_name,
            contents=new_local,
            content_type='text/plain'
        )
    os.remove(image_path)
    os.remove(thumb_path)

    print('Uploaded object %s to container %s' % (object_name, new_container_name))
EOF

Install the python libraries necessary for the program execution using pip. The libraries need to be installed at the root level of the directory.
```
pip install module-name -t path/to/dir
```
In this example, we would install the library Pillow in the project directory.
```
$ pip install Pillow -t ~/qinling_test
```
Note

Qinling’s default Python runtime includes most of the OpenStack project SDKs, so you don’t need to include python-swiftclient in your function code package, but you can optionally include it for your local testing.
Add the contents of the whole directory to a zip file which is now your function code package. Make sure you zip the contents of the directory and not the directory itself.
```
$ cd ~/qinling_test; zip -r9 ~/qinling_test/resize_image.zip .
```

Create function and get the function ID, replace the runtime_id with the one in your deployment.

$ runtime_id=601efeb8-3e41-4e5c-a12a-986dbda252e3
$ openstack function create --name resize_image \
    --runtime $runtime_id \
    --entry resize_image.main \
    --package ~/qinling_test/resize_image.zip
+-------------+-------------------------------------------------------------------------+
| Field       | Value                                                                   |
+-------------+-------------------------------------------------------------------------+
| id          | f8b18de6-1751-46d6-8c0d-0f1ecf943d12                                    |
| name        | resize_test                                                             |
| description | None                                                                    |
| count       | 0                                                                       |
| code        | {u'source': u'package', u'md5sum': u'ae7ad9ae450a8c5c31dca8e96f42247c'} |
| runtime_id  | 685c1e6c-e175-4b32-9ec4-244d39c1077e                                    |
| entry       | resize_image.main                                                       |
| project_id  | a1e58c83923a4e2ca9370df6007c7fe6                                        |
| created_at  | 2018-07-03 04:38:50.147277                                              |
| updated_at  | None                                                                    |
| cpu         | 100                                                                     |
| memory_size | 33554432                                                                |
+-------------+-------------------------------------------------------------------------+
$ function_id=f8b18de6-1751-46d6-8c0d-0f1ecf943d12

Upload an image to Swift.

$ curl -SL https://docs.openstack.org/arch-design/_images/osog_0001.png -o ~/origin.jpg
$ openstack container create origin_folder
+---------------------------------------+---------------+------------------------------------+
| account                               | container     | x-trans-id                         |
+---------------------------------------+---------------+------------------------------------+
| AUTH_a1e58c83923a4e2ca9370df6007c7fe6 | origin_folder | tx664a23a4a6e345b6af30d-005b3b6127 |
+---------------------------------------+---------------+------------------------------------+
$ openstack object create origin_folder ~/origin.jpg --name image
+--------+---------------+----------------------------------+
| object | container     | etag                             |
+--------+---------------+----------------------------------+
| image  | origin_folder | 07855978284adfcbbf76954a7c654a74 |
+--------+---------------+----------------------------------+
$ openstack object show origin_folder image
+----------------+---------------------------------------+
| Field          | Value                                 |
+----------------+---------------------------------------+
| account        | AUTH_a1e58c83923a4e2ca9370df6007c7fe6 |
| container      | origin_folder                         |
| content-length | 45957                                 |
| content-type   | application/octet-stream              |
| etag           | 07855978284adfcbbf76954a7c654a74      |
| last-modified  | Tue, 03 Jul 2018 11:44:33 GMT         |
| object         | image                                 |
+----------------+---------------------------------------+

Invoke the function by specifying function_id and the function inputs as well.

$ openstack function execution create $function_id --input '{"container_name": "origin_folder", "object_name": "image"}'
+------------------+-------------------------------------------------------------+
| Field            | Value                                                       |
+------------------+-------------------------------------------------------------+
| id               | 04c60ae7-08c9-454c-9b2c-0bbf36391159                        |
| function_id      | d3de49fc-7488-4635-aa48-84e754881eb8                        |
| function_version | 0                                                           |
| description      | None                                                        |
| input            | {"object_name": "image", "container_name": "origin_folder"} |
| result           | {"duration": 2.74, "output": null}                          |
| status           | success                                                     |
| sync             | True                                                        |
| project_id       | a1e58c83923a4e2ca9370df6007c7fe6                            |
| created_at       | 2018-07-03 09:12:12                                         |
| updated_at       | 2018-07-03 09:12:16                                         |
+------------------+-------------------------------------------------------------+

Check the function execution log.

$ openstack function execution log show 04c60ae7-08c9-454c-9b2c-0bbf36391159
Start execution: 04c60ae7-08c9-454c-9b2c-0bbf36391159
Downloaded object image from container origin_folder
Resized.
New container origin_folder_resized created.
Uploaded object image to container origin_folder_resized
Finished execution: 04c60ae7-08c9-454c-9b2c-0bbf36391159

Verify that a new object of smaller size was created in a new container in Swift.

$ openstack container list
+-----------------------+
| Name                  |
+-----------------------+
| origin_folder         |
| origin_folder_resized |
+-----------------------+
$ openstack object list origin_folder_resized
+-------+
| Name  |
+-------+
| image |
+-------+
$ openstack object show origin_folder_resized image
+----------------+---------------------------------------+
| Field          | Value                                 |
+----------------+---------------------------------------+
| account        | AUTH_a1e58c83923a4e2ca9370df6007c7fe6 |
| container      | origin_folder_resized                 |
| content-length | 31779                                 |
| content-type   | text/plain                            |
| etag           | f737cc7f0fe5c15d8a6897c8fe159c02      |
| last-modified  | Tue, 03 Jul 2018 11:46:40 GMT         |
| object         | image                                 |
+----------------+---------------------------------------+

Pay attention to the object content-length value which is smaller than the original object.

Creating a function using OpenStack Swift¶

OpenStack object storage service, swift can be integrated with Qinling to create functions. You can upload your function package to swift and create the function by specifying the container name and object name in Swift. In this example the function would return "Hello, World" by default, you can replace the string with the function input. The steps assume there is already a Python 2.7 runtime available in the deployment.

Create a function deployment package.

$ mkdir ~/qinling_swift_test
$ cd ~/qinling_swift_test
$ cat <<EOF > hello_world.py

def main(name='World',**kwargs):
    ret = 'Hello, %s' % name
    return ret
EOF

$ cd ~/qinling_swift_test && zip -r ~/qinling_swift_test/hello_world.zip ./*

Upload the file to swift

$ openstack container create functions

+---------------------------------------+------------------+------------------------------------+
| account                               | container        | x-trans-id                         |
+---------------------------------------+------------------+------------------------------------+
| AUTH_6ae7142bff0542d8a8f3859ffa184236 | functions        | 9b45bef5ab2658acb9b72ee32f39dbc8   |
+---------------------------------------+------------------+------------------------------------+

$ openstack object create functions hello_world.zip

+-----------------+-----------+----------------------------------+
| object          | container | etag                             |
+-----------------+-----------+----------------------------------+
| hello_world.zip | functions | 9b45bef5ab2658acb9b72ee32f39dbc8 |
+-----------------+-----------+----------------------------------+

$ openstack object show functions hello_world.zip

+----------------+---------------------------------------+
| Field          | Value                                 |
+----------------+---------------------------------------+
| account        | AUTH_6ae7142bff0542d8a8f3859ffa184236 |
| container      | functions                             |
| content-length | 246                                   |
| content-type   | application/zip                       |
| etag           | 9b45bef5ab2658acb9b72ee32f39dbc8      |
| last-modified  | Wed, 18 Jul 2018 17:45:23 GMT         |
| object         | hello_world.zip                       |
+----------------+---------------------------------------+

Create a function and get the function ID, replace the runtime_id with the one in your deployment. Also, specify swift container and object name.

$ openstack function create --name hello_world \
--runtime $runtime_id \
--entry hello_world.main \
--container functions \
--object hello_world.zip

+-------------+----------------------------------------------------------------------------------------------+
| Field       | Value                                                                                        |
+-------------+----------------------------------------------------------------------------------------------+
| id          | f1102bca-fbb4-4baf-874d-ed33bf8251f7                                                         |
| name        | hello_world                                                                                  |
| description | None                                                                                         |
| count       | 0                                                                                            |
| code        | {u'source': u'swift', u'swift': {u'object': u'hello_world.zip', u'container': u'functions'}} |
| runtime_id  | 0d8bcf73-910b-4fec-86b1-38ace8bd0766                                                         |
| entry       | hello_world.main                                                                             |
| project_id  | 6ae7142bff0542d8a8f3859ffa184236                                                             |
| created_at  | 2018-07-18 17:46:29.974506                                                                   |
| updated_at  | None                                                                                         |
| cpu         | 100                                                                                          |
| memory_size | 33554432                                                                                     |
+-------------+----------------------------------------------------------------------------------------------+

Invoke the function by specifying function_id

$ function_id=f1102bca-fbb4-4baf-874d-ed33bf8251f7
$ openstack function execution create $function_id

+------------------+-----------------------------------------------+
| Field            | Value                                         |
+------------------+-----------------------------------------------+
| id               | 3451393d-60c6-4172-bbdf-c681929fae07          |
| function_id      | f1102bca-fbb4-4baf-874d-ed33bf8251f7          |
| function_version | 0                                             |
| description      | None                                          |
| input            | None                                          |
| result           | {"duration": 0.031, "output": "Hello, World"} |
| status           | success                                       |
| sync             | True                                          |
| project_id       | 6ae7142bff0542d8a8f3859ffa184236              |
| created_at       | 2018-07-18 17:49:46                           |
| updated_at       | 2018-07-18 17:49:48                           |
+------------------+-----------------------------------------------+

It is very easy and simple to use Qinling with swift. We have successfully created and invoked a function using OpenStack Swift.

updated: 2018-08-29 05:10

Except where otherwise noted, this document is licensed under Creative Commons Attribution 3.0 License. See all OpenStack Legal Documents.