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.

  1. Create a directory, for example ~/qinling_test

    mkdir ~/qinling_test

  2. 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

  3. 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.

  4. 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 .

  5. 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

  6. 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                                 |
+----------------+---------------------------------------+

  7. 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                                         |
+------------------+-------------------------------------------------------------+

  8. 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

  9. 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.

Create a function stored in 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.

  1. 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 ./*

  2. 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                       |
+----------------+---------------------------------------+

  3. 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                                                                                     |
+-------------+----------------------------------------------------------------------------------------------+

  4. 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.

Create image(docker) type function

With the help of Docker Hub you would be able to create image type functions in Qinling. As a prerequisite, you need to have a Docker Hub account. In the following instructions replace DOCKER_USER with your own docker hub username.

  1. In this tutorial we would be create docker image with latest Python3 installed. We will create a python script which would be included in the image. Finally we create a Dockerfile to build the image.

    mkdir ~/qinling_test
cd ~/qinling_test
cat <<EOF > ~/qinling_test/hello.py
import sys
import time

def main():
    print('Hello', sys.argv[1])
    time.sleep(3)

if __name__ == '__main__':
    main()
EOF

cat <<EOF > ~/qinling_test/Dockerfile
FROM python:3.7.0-alpine3.7
COPY . /qinling_test
WORKDIR /qinling_test
ENTRYPOINT [ "python", "./hello.py" ]
CMD ["Qinling"]
EOF

  2. You need first run docker login to authenticate, build the image and push to Docker Hub.

    docker login
docker build -t DOCKER_USER/qinling_test .
docker push DOCKER_USER/qinlng_test

  3. Create an image type function by providing the docker image name.

    $ openstack function create --name docker_test --image DOCKER_USER/qinling_test
+-------------+--------------------------------------------------------------+
| Field       | Value                                                        |
+-------------+--------------------------------------------------------------+
| id          | 6fa6932d-ee43-41d4-891c-77a96b52c697                         |
| name        | docker_test                                                  |
| description | None                                                         |
| count       | 0                                                            |
| code        | {u'source': u'image', u'image': u'DOCKER_USER/qinling_test'} |
| runtime_id  | None                                                         |
| entry       | None                                                         |
| project_id  | 6ae7142bff0542d8a8f3859ffa184236                             |
| created_at  | 2018-08-05 00:37:07.336918                                   |
| updated_at  | None                                                         |
| cpu         | 100                                                          |
| memory_size | 33554432                                                     |
+-------------+--------------------------------------------------------------+

  4. Invoke the function by specifying the function name or ID.

    $ openstack function execution create docker_test
+------------------+--------------------------------------+
| Field            | Value                                |
+------------------+--------------------------------------+
| id               | 8fe0e2e9-2133-4abb-8cd4-f2f14935cab4 |
| function_id      | 6fa6932d-ee43-41d4-891c-77a96b52c697 |
| function_version | 0                                    |
| description      | None                                 |
| input            | None                                 |
| result           | {"duration": 3}                      |
| status           | success                              |
| sync             | True                                 |
| project_id       | 6ae7142bff0542d8a8f3859ffa184236     |
| created_at       | 2018-08-05 00:37:25                  |
| updated_at       | 2018-08-05 00:37:29                  |
+------------------+--------------------------------------+

  5. Check the execution log.

    $ openstack function execution log show 8fe0e2e9-2133-4abb-8cd4-f2f14935cab4
Hello Qinling

Config timeout for the function

In the cloud, you need to pay for the cloud resources that are used to run your Qinling function. To prevent your function from running indefinitely, you specify a timeout. When the specified timeout is reached, Qinling terminates execution of the function. We recommend you set this value based on your expected execution time. The default is 5 seconds and you can set it up to 300 seconds.

Note

This guide assumes you already have a Python2 or Python3 runtime available in the deployment

  1. Create a Python function that simply sleeps for 10 seconds to simulate a long-running function.

    mkdir ~/qinling_test && cd ~/qinling_test
cat <<EOF > test_sleep.py
import time
def main(seconds=10, **kwargs):
    time.sleep(seconds)
EOF

  2. Create the Qinling function.

    $ openstack function create --runtime $runtime_id --entry test_sleep.main --file ~/qinling_test/test_sleep.py --name test_sleep
+-------------+-------------------------------------------------------------------------+
| Field       | Value                                                                   |
+-------------+-------------------------------------------------------------------------+
| id          | 6c2cb248-5065-4a0a-9b7a-06818693358c                                    |
| name        | test_sleep                                                              |
| description | None                                                                    |
| count       | 0                                                                       |
| code        | {u'source': u'package', u'md5sum': u'c0830d40dbef48b11af9e63a653799ac'} |
| runtime_id  | ba429da0-b800-4f27-96ea-eb527bd68004                                    |
| entry       | test_sleep.main                                                         |
| project_id  | d256a42b9f8e4d66805d91655b36a318                                        |
| created_at  | 2018-09-10 01:43:06.250137                                              |
| updated_at  | None                                                                    |
| cpu         | 100                                                                     |
| memory_size | 33554432                                                                |
| timeout     | 5                                                                       |
+-------------+-------------------------------------------------------------------------+

  3. Invoke the function. You will see the execution is terminated after about 5 seconds(the default timeout).

    $ openstack function execution create test_sleep
+------------------+--------------------------------------------------------------+
| Field            | Value                                                        |
+------------------+--------------------------------------------------------------+
| id               | e096f4b3-85a7-4356-93e9-5f583e802aa2                         |
| function_id      | 6c2cb248-5065-4a0a-9b7a-06818693358c                         |
| function_version | 0                                                            |
| description      | None                                                         |
| input            | None                                                         |
| result           | {"duration": 5.097, "output": "Function execution timeout."} |
| status           | failed                                                       |
| sync             | True                                                         |
| project_id       | d256a42b9f8e4d66805d91655b36a318                             |
| created_at       | 2018-09-10 01:44:46                                          |
| updated_at       | 2018-09-10 01:44:55                                          |
+------------------+--------------------------------------------------------------+

  4. Update the function by setting a longer timeout value.

    $ openstack function update test_sleep --timeout 15
+-------------+-------------------------------------------------------------------------+
| Field       | Value                                                                   |
+-------------+-------------------------------------------------------------------------+
| id          | 6c2cb248-5065-4a0a-9b7a-06818693358c                                    |
| name        | test_sleep                                                              |
| description | None                                                                    |
| count       | 1                                                                       |
| code        | {u'source': u'package', u'md5sum': u'c0830d40dbef48b11af9e63a653799ac'} |
| runtime_id  | ba429da0-b800-4f27-96ea-eb527bd68004                                    |
| entry       | test_sleep.main                                                         |
| project_id  | d256a42b9f8e4d66805d91655b36a318                                        |
| created_at  | 2018-09-10 01:43:06                                                     |
| updated_at  | 2018-09-10 02:01:38.510319                                              |
| cpu         | 100                                                                     |
| memory_size | 33554432                                                                |
| timeout     | 15                                                                      |
+-------------+-------------------------------------------------------------------------+

  5. Invoke the function again to verify the function is successfully executed.

    $ openstack function execution create test_sleep
+------------------+--------------------------------------+
| Field            | Value                                |
+------------------+--------------------------------------+
| id               | 6dd91e1d-df91-4e19-92b6-3bec474ee09a |
| function_id      | 6c2cb248-5065-4a0a-9b7a-06818693358c |
| function_version | 0                                    |
| description      | None                                 |
| input            | None                                 |
| result           | {"duration": 10.143, "output": null} |
| status           | success                              |
| sync             | True                                 |
| project_id       | d256a42b9f8e4d66805d91655b36a318     |
| created_at       | 2018-09-10 02:03:56                  |
| updated_at       | 2018-09-10 02:04:06                  |
+------------------+--------------------------------------+