Declarative HTTP service entry point.
Project description
py2http
Dispatching Python functions as http services.
You have some python objects and want to get an "equivalent" http service from them...
Usage
Run a basic HTTP service from a list of functions.
from py2http.service import run_app
# Define or import functions
def add(a, b):
return a + b
def multiply(a, b):
return a * b
class Divider:
def __init__(self, dividend):
self.dividend = divident
def divide(self, divisor):
return self.dividend / divisor
divider_from_ten = Divider(10)
# Make a list of functions or instance methods
func_list = [add, multiply, divider_from_ten.divide]
# Create an HTTP server
run_app(func_list)
The HTTP server will listen on port 3030 by default.
# Test the server in a separate process
import requests
url = 'http://localhost:3030/add'
add_args = {'a': 20, 'b': 22}
requests.post(url, json=add_args).json()
# should return 42
Configuration
run_app
accept many configuration values to customize the handling of HTTP requests and responses. Configuration documentation is listed in the file config.yaml
.
Method transformation
Expose class methods by flattening the init -> method call process.
from py2http import run_app
from py2http.decorators import mk_flat
class Adder:
def __init__(self, a):
self.a = a
def add(self, b):
return self.a + b
add = mk_flat(Adder, Adder.add, func_name='add')
func_list = [add]
run_app(func_list)
Input mapping
By default, the server will only accept JSON requests and parse the values from the request body as keyword arguments. You can define custom input mappers to perform extra handling on the JSON body or directly on the HTTP library request object, such as default injection or type mapping.
from numpy import array
import soundfile
from py2http.decorators import handle_json_req
from my_service.data import fetch_user_data
@handle_json_req # extracts the JSON body and passes it to the input mapper as a dict
def array_input_mapper(input_kwargs):
return {'arr': array(input_kwargs.get('arr', [])),
'scalar': input_kwargs.get('scalar', 1)}
@handle_multipart_req # extracts a multipart body and passes it as a dict
def sound_file_input_mapper(input_kwargs):
file_input = input_kwargs['file_upload']
filename = file_input.filename
file_bytes = BytesIO(file_input.file)
wf, sr = soundfile.read(file_bytes)
return dict(input_kwargs, wf=wf, sr=sr, filename=filename)
def custom_header_input_mapper(req): # takes a raw aiohttp request
user = req.headers.get('User', '')
return {'user': user}
def array_multiplier(arr, scalar):
return arr * scalar
def save_audio(wf, sr, filename, storage_path='/audio'):
target = os.path.join(storage_path, filename)
soundfile.write(target, wf, sr)
def get_user_data(user):
return fetch_user_data(user)
array_multiplier.input_mapper = array_input_mapper
save_audio.input_mapper = sound_file_input_mapper
get_user_data.input_mapper = custom_header_input_mapper
Output mapping
By default, the server will send the return value of the handler function in an HTTP response in JSON format. You can define custom output mappers to perform extra handling or type conversion.
from io import BytesIO
import soundfile
from py2http.decorators import send_json_resp, send_html_resp
from my_service.data import fetch_blog
@send_json_resp # sends a JSON response
def array_output_mapper(output, input_kwargs):
return {'array_value': output['array_value'].tolist()}
@send_html_resp # sends an HTML response
def mk_html_list(output, input_kwargs):
tag = input_kwargs.get('tag', 'p')
item_list = output.split('\n')
result = [f'<{tag}>{item}</{tag}>' for item in item_list]
return ''.join(result)
def return_wav(output, input_kwargs):
wf, sr = output
wf_bytes = BytesIO()
soundfile.write(wf_bytes, wf, sr)
binary_result = wf_bytes.read()
return web.Response(body=binary_result, content_type='application/octet-stream')
def array_multiplier(arr, scalar):
return arr * scalar
def get_blog_posts(page):
return fetch_blog(page)
def download_audio(filename):
with open(filename) as fp:
wf, sr = soundfile.read(fp)
return wf, sr
array_multipler.output_mapper = array_output_mapper
get_blog_posts.output_mapper = mk_html_list
download_audio.output_mapper = return_wav
Error handling
TODO
Client generation
Py2http generates an OpenAPI specification for the server before running. You can use this document with any OpenAPI-compatible client tools. To extract the specification, you can generate a server application object before running it.
import json
from py2http import mk_app, run_app
def add(a, b):
return a + b
func_list = [add]
app = mk_app(func_list)
openapi_spec = app.openapi_spec
with open('~/openapi.json', 'w') as fp:
json.dump(openapi_spec, fp)
run_app(app, port=3030)
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