do-function-tester A small codebase to test DigitalOcean Function blocking=false functionality

Code repository author: Alexandre Harano

This project provides a small DigitalOcean Function using Python to validate blocking=false functionality.

Project Configuration

This project uses the twelve-factor app methodology.

Environment variables in this project can be stored using a .env (dot env) file. For initial setup, a sample is provided as .env.sample.

A description of each of the variables is provided as the following list.

• FUNCTION_URL: the DigitalOcean Function URL to be called
• AUTHORIZATION_TOKEN: a string value to be used as the Functions REST API Authorization token

Project Installation

First, clone this repo:

$ git clone https://github.com/ayharano/do-function-tester.git

After cloning the repository, change the directory to the project root. All instructions below, including configuring the virtual environment and running the project, depend on being in the project root directory.

Consistency of contributions using pre-commit

To maintain consistency between individual commits, this repo is adopting the use of pre-commit.

The recommended way to install it for this repo is by installing via pipx. After installing pipx, issue the following commands:

$ pipx install pre-commit
$ pre-commit install --install-hooks --overwrite

pre-commit is configured to also run per push and pull requests in GitHub workflow.

Python Version and Virtual Environment Setup

This project was tested by using CPython 3.10. In order to keep multiple versions of the Python interpreter, we recommend the use of pyenv.

• pyenv (Linux, macOS): link
• pyenv for Windows (Windows): link

Once it is installed, we can use the same version as the one used during this project development, which was CPython 3.12.1.

Run the following:

$ pyenv install 3.10.3  # install CPython 3.10.3
$ pyenv local 3.10.3    # select CPython 3.10.3 as the local interpreter

As a directory name for the virtual env, for this tutorial we will use it as virtualenvironment. If you prefer another name, just replace all the occurrences from here.

To install a virtual env, run the following:

$ python -m venv virtualenvironment

This way, a directory named virtualenvironment will be created at the project root to store the Python project dependencies.

Using the local virtual env

Regarding the installation and the use of virtual envs, more details can be found at the venv module documentation.

To use the virutal env, the instructions depend on the target operating system:

• venv for Linux or macOS

$ source virtualenvironment/bin/activate

• venv for Windows (PowerShell)

virtualenvironment\Scripts\Activate.ps1

Installing the project dependencies in the virtual env

Once the virtual env is activated, run:

python -m pip install --upgrade pip && python -m pip install --editable '.[local]' && python -m pip install --upgrade tzdata

This command is a chained call of 3 executions, being

1. upgrading the local pip to its most recent version
2. installing all the project dependencies, including the ones for local dev use, and installing the project as an editable install, and
3. enforce the most recent version of tzdata, which is used by Python to manage timezone data without relying on the data from the target operating system (more details at the zoneinfo module documentation)

DigitalOcean Functions Usage

DigitalOcean Functions Deployment

To deploy this function, a DigitalOcean account is required.

For this tutorial, we rely on doctl CLI (installation instructions).

Following the Functions Quickstart, we must create a namespace before deploying a Function. Two parameters are required:

• label: an arbitrary label for the namespace
• region: one of the available DigitalOcean's datacenter - list for Functions

For this example, we used functions-ns as its label and nyc as its region:

$ doctl serverless namespaces create --label functions-ns --region nyc

If it is correctly configured, an output similar to the following should be displayed

Connected to functions namespace 'fn-01234567-89ab-cdef-0123-456789abcdef' on API host 'https://faas-nyc1-abcdef01.doserverless.co'

To deploy the function(s), run:

$ doctl serverless deploy .  # yes, it is a dot after deploy

If it is correctly runs, an output such as the following should be displayed

Deploying '/home/user/projects/do-function-tester'
  to namespace 'fn-01234567-89ab-cdef-0123-456789abcdef'
  on host 'https://faas-nyc1-abcdef01.doserverless.co'

Deployed functions ('doctl sls fn get <funcName> --url' for URL):
  - tester/blocking_false_handler

DigitalOcean Functions Tester

Environmental Variables

To test the Function, we need to populate the environmental variables:

FUNCTION_URL

As we will need the Function URL, we should run the suggested command:

$ doctl sls fn get tester/blocking_false_handler --url

The output is a URL similar to this

https://faas-nyc1-abcdef01.doserverless.co/api/v1/web/fn-01234567-89ab-cdef-0123-456789abcdef/tester/blocking_false_handler

We can set that value in the .env file as FUNCTION_URL:

FUNCTION_URL=https://faas-nyc1-abcdef01.doserverless.co/api/v1/web/fn-01234567-89ab-cdef-0123-456789abcdef/tester/blocking_false_handler

AUTHORIZATION_TOKEN

Follow the instructions described in Call a Function Asynchronously using curl and the REST API to retrieve the token.

Having its full value (everything after Authorization:), set it in the .env file as AUTHORIZATION_TOKEN:

AUTORIZATION_TOKEN=Basic VeryBase64EncodedValue=

Issue Asynchronous Function Call

If the project was correctly installed as described in the Project Installation section, we can just test the Function by running

$ python -m tester issue any value here after issue will be grouped as a list

Example output:

{'after_request': '2024-02-16T18:46:24.745284+00:00',
 'before_request': '2024-02-16T18:46:24.319217+00:00',
 'body': {'activationId': 'abcdef0123456789abcdef0123456789'},
 'status_code': 202,
 'time_diff': 0.426067}

Retrieve Activation Record

As described in Retrieve Activation Records Using curl and the REST API, we can retrieve the actual values using the activationId.

If the project was correctly installed as described in the Project Installation section, we can just test the Function by running

$ python -m tester retrieve abcdef0123456789abcdef0123456789

where abcdef0123456789abcdef0123456789 would be the activationId value.

Example output:

{'after_request': '2024-02-16T18:47:09.740636+00:00',
 'before_request': '2024-02-16T18:47:09.255087+00:00',
 'body': {'activationId': 'abcdef0123456789abcdef0123456789',
          'annotations': [{'key': 'path',
                           'value': 'fn-01234567-89ab-cdef-0123-456789abcdef/tester/blocking_false_handler'},
                          {'key': 'waitTime', 'value': 769},
                          {'key': 'uuid',
                           'value': 'fedcba98-7654-3210-0123-456789abcdef'},
                          {'key': 'entry', 'value': 'main'},
                          {'key': 'user_id', 'value': '12345678'},
                          {'key': 'gbs', 'value': 0.0125},
                          {'key': 'kind', 'value': 'python:3.9'},
                          {'key': 'timeout', 'value': False},
                          {'key': 'limits',
                           'value': {'logs': 5,
                                     'memory': 128,
                                     'timeout': 1000}},
                          {'key': 'initTime', 'value': 10}],
          'duration': 2,
          'end': 1708109185446,
          'logs': [],
          'name': 'blocking_false_handler',
          'namespace': 'fn-01234567-89ab-cdef-0123-456789abcdef',
          'publish': False,
          'response': {'result': {'body': {'list_args': ['any',
                                                         'value',
                                                         'here',
                                                         'after',
                                                         'issue',
                                                         'will',
                                                         'be',
                                                         'grouped',
                                                         'as',
                                                         'a',
                                                         'list'],
                                           'received_at': '2024-02-16T18:46:25.445336+00:00',
                                           'sent_at_arg': '2024-02-16T18:46:24.319205+00:00'},
                                  'statusCode': 202},
                       'size': 232,
                       'status': 'success',
                       'success': True},
          'start': 1708109185444,
          'subject': '01234567-89ab-cdef-0123-456789abcdef',
          'version': '0.0.1'},
 'status_code': 200,
 'time_diff': 0.485549}