gracy 1.27.1

Gracefully manage your API interactions

Gracefully manage your API interactions

Gracy helps you handle failures, logging, retries, throttling, and tracking for all your HTTP interactions. Gracy uses httpx under the hood.

"Let Gracy do the boring stuff while you focus on your application"

---

Summary

• 🧑‍💻 Get started
  • Installation
  • Usage
    • Simple example
    • More examples
• Settings
  • Strict/Allowed status code
  • Custom Validators
  • Parsing
  • Retry
  • Throttling
  • Concurrent Requests
  • Logging
  • Custom Exceptions
• Reports
  • Logger
  • List
  • Table
• Replay requests
  • Recording
  • Replay
• Advanced Usage
  • Customizing/Overriding configs per method
  • Customizing HTTPx client
  • Overriding default request timeout
  • Creating a custom Replay data source
  • Hooks before/after request
    • Common Hooks
      • HttpHeaderRetryAfterBackOffHook
      • RateLimitBackOffHook
• 📚 Extra Resources
• Change log
• License
• Credits

🧑‍💻 Get started

Installation

pip install gracy

OR

poetry add gracy

Usage

Examples will be shown using the PokeAPI.

Simple example

# 0. Import
import asyncio
import typing as t
from gracy import BaseEndpoint, Gracy, GracyConfig, LogEvent, LogLevel

# 1. Define your endpoints
class PokeApiEndpoint(BaseEndpoint):
    GET_POKEMON = "/pokemon/{NAME}" # 👈 Put placeholders as needed

# 2. Define your Graceful API
class GracefulPokeAPI(Gracy[str]):
    class Config:  # type: ignore
        BASE_URL = "https://pokeapi.co/api/v2/" # 👈 Optional BASE_URL
        # 👇 Define settings to apply for every request
        SETTINGS = GracyConfig(
          log_request=LogEvent(LogLevel.DEBUG),
          log_response=LogEvent(LogLevel.INFO, "{URL} took {ELAPSED}"),
          parser={
            "default": lambda r: r.json()
          }
        )

    async def get_pokemon(self, name: str) -> t.Awaitable[dict]:
        return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})

pokeapi = GracefulPokeAPI()

async def main():
    try:
      pokemon = await pokeapi.get_pokemon("pikachu")
      print(pokemon)

    finally:
        pokeapi.report_status("rich")


asyncio.run(main())

More examples

• PokeAPI with retries, parsers, logs
• PokeAPI with throttling
• PokeAPI with SQLite replay
• PokeAPI with Mongo replay

Settings

Strict/Allowed status code

By default Gracy considers any successful status code (200-299) as successful.

Strict

You can modify this behavior by defining a strict status code or increase the range of allowed status codes:

from http import HTTPStatus

GracyConfig(
  strict_status_code=HTTPStatus.CREATED
)

or a list of values:

from http import HTTPStatus

GracyConfig(
  strict_status_code={HTTPStatus.OK, HTTPStatus.CREATED}
)

Using strict_status_code means that any other code not specified will raise an error regardless of being successful or not.

Allowed

You can also keep the behavior, but extend the range of allowed codes.

from http import HTTPStatus

GracyConfig(
  allowed_status_code=HTTPStatus.NOT_FOUND
)

or a list of values

from http import HTTPStatus

GracyConfig(
  allowed_status_code={HTTPStatus.NOT_FOUND, HTTPStatus.FORBIDDEN}
)

Using allowed_status_code means that all successful codes plus your defined codes will be considered successful.

This is quite useful for parsing as you'll see soon.

⚠️ Note that strict_status_code takes precedence over allowed_status_code, probably you don't want to combine those. Prefer one or the other.

Custom Validators

You can implement your own custom validator to do further checks on the response and decide whether to consider the request failed (and as consequence trigger retries if they're set).

from gracy import GracefulValidator

class MyException(Exception):
  pass

class MyCustomValidator(GracefulValidator):
    def check(self, response: httpx.Response) -> None:
        jsonified = response.json()
        if jsonified.get('error', None):
          raise MyException("Error is not expected")

        return None

...

class Config:
  SETTINGS = GracyConfig(
    ...,
    retry=GracefulRetry(retry_on=MyException, ...),  # Set up retry to work whenever our validator fails
    validators=MyCustomValidator(),  # Set up validator
  )

Parsing

Parsing allows you to handle the request based on the status code returned.

The basic example is parsing json:

GracyConfig(
  parser={
    "default": lambda r: r.json()
  }
)

In this example all successful requests will automatically return the json() result.

You can also narrow it down to handle specific status codes.

class Config:
  SETTINGS = GracyConfig(
    ...,
    allowed_status_code=HTTPStatusCode.NOT_FOUND,
    parser={
      "default": lambda r: r.json()
      HTTPStatusCode.NOT_FOUND: None
    }
  )

async def get_pokemon(self, name: str) -> dict| None:
  # 👇 Returns either dict or None
  return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})

Or even customize exceptions to improve your code readability:

class PokemonNotFound(GracyUserDefinedException):
  ... # More on exceptions below

class Config:
  GracyConfig(
    ...,
    allowed_status_code=HTTPStatusCode.NOT_FOUND,
    parser={
      "default": lambda r: r.json()
      HTTPStatusCode.NOT_FOUND: PokemonNotFound
    }
  )

async def get_pokemon(self, name: str) -> Awaitable[dict]:
  # 👇 Returns either dict or raises PokemonNotFound
  return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})

Retry

Who doesn't hate flaky APIs? 🙋

Yet there're many of them.

Using tenacity, backoff, retry, aiohttp_retry, and any other retry libs is NOT easy enough. 🙅

You still would need to code the implementation for each request which is annoying.

Here's how Gracy allows you to implement your retry logic:

class Config:
  GracyConfig(
    retry=GracefulRetry(
      delay=1,
      max_attempts=3,
      delay_modifier=1.5,
      retry_on=None,
      log_before=None,
      log_after=LogEvent(LogLevel.WARNING),
      log_exhausted=LogEvent(LogLevel.CRITICAL),
      behavior="break",
    )
  )

Parameter	Description	Example
delay	How many seconds to wait between retries	2 would wait 2 seconds, 1.5 would wait 1.5 seconds, and so on
max_attempts	How many times should Gracy retry the request?	10 means 1 regular request with additional 10 retries in case they keep failing. 1 should be the minimum
delay_modifier	Allows you to specify increasing delay times by multiplying this value to delay	Setting 1 means no delay change. Setting 2 means delay will be doubled every retry
retry_on	Should we retry for which status codes/exceptions? None means for any non successful status code or exception	HTTPStatus.BAD_REQUEST, or {HTTPStatus.BAD_REQUEST, HTTPStatus.FORBIDDEN}, or Exception or {Exception, HTTPStatus.NOT_FOUND}
log_before	Specify log level. None means don't log	More on logging later
log_after	Specify log level. None means don't log	More on logging later
log_exhausted	Specify log level. None means don't log	More on logging later
behavior	Allows you to define how to deal if the retry fails. pass will accept any retry failure	pass or break (default)
overrides	Allows to override delay based on last response status code	{HTTPStatus.BAD_REQUEST: OverrideRetryOn(delay=0), HTTPStatus.INTERNAL_SERVER_ERROR: OverrideRetryOn(delay=10)}

Throttling

Rate limiting issues? No more.

Gracy helps you proactively deal with it before any API throws 429 in your face.

Creating rules

You can define rules per endpoint using regex:

SIMPLE_RULE = ThrottleRule(
  url_pattern=r".*",
  max_requests=2
)
print(SIMPLE_RULE)
# Output: "2 requests per second for URLs matching re.compile('.*')"

COMPLEX_RULE = ThrottleRule(
  url_pattern=r".*\/pokemon\/.*",
  max_requests=10,
  per_time=timedelta(minutes=1, seconds=30),
)
print(COMPLEX_RULE)
# Output: 10 requests per 90 seconds for URLs matching re.compile('.*\\/pokemon\\/.*')

Setting throttling

You can set up logging and assign rules as:

class Config:
  GracyConfig(
    throttling=GracefulThrottle(
        rules=ThrottleRule(r".*", 2), # 2 reqs/s for any endpoint
        log_limit_reached=LogEvent(LogLevel.ERROR),
        log_wait_over=LogEvent(LogLevel.WARNING),
    ),
  )

Concurrent Requests

Maybe the API you're hitting have some slow endpoints and you want to ensure that no more than a custom number of requests are being made concurrently.

You can define a ConcurrentRequestLimit config.

The simplest usage is:

from gracy import ConcurrentRequestLimit


class Config:
  GracyConfig(
    concurrent_requests=ConcurrentRequestLimit(
      limit=1, # How many concurrent requests
      log_limit_reached=LogEvent(LogLevel.WARNING),
      log_limit_freed=LogEvent(LogLevel.INFO),
    ),
  )

But you can also define it easily per method as:

class MyApiClient(Gracy[Endpoint]):

  @graceful(concurrent_requests=5)
  async def get_concurrently_five(self, name: str):
      ...

Logging

You can define and customize logs for events by using LogEvent and LogLevel:

verbose_log = LogEvent(LogLevel.CRITICAL)
custom_warn_log = LogEvent(LogLevel.WARNING, custom_message="{METHOD} {URL} is quite slow and flaky")
custom_error_log = LogEvent(LogLevel.INFO, custom_message="{URL} returned a bad status code {STATUS}, but that's fine")

Note that placeholders are formatted and replaced later on by Gracy based on the event type, like:

Placeholders per event

Placeholder	Description	Example	Supported Events
{URL}	Full url being targetted	https://pokeapi.co/api/v2/pokemon/pikachu	All
{UURL}	Full Unformatted url being targetted	https://pokeapi.co/api/v2/pokemon/{NAME}	All
{ENDPOINT}	Endpoint being targetted	/pokemon/pikachu	All
{UENDPOINT}	Unformatted endpoint being targetted	/pokemon/{NAME}	All
{METHOD}	HTTP Request being used	GET, POST	All
{STATUS}	Status code returned by the response	200, 404, 501	After Request
{ELAPSED}	Amount of seconds taken for the request to complete	Numeric	After Request
{REPLAY}	A placeholder that is displayed only when request is replayed	REPLAYED when replay, otherwise it's a blank str (``)	After Request
{IS_REPLAY}	Boolean value to show whether it's replayed or not	String with TRUE when replayed or FALSE	After Request
{RETRY_DELAY}	How long Gracy will wait before repeating the request	Numeric	Any Retry event
{RETRY_CAUSE}	What caused the retry logic to trigger	[Bad Status Code: 404], [Request Error: ConnectionTimeout]	Any Retry event
{CUR_ATTEMPT}	Current attempt count for the current request	Numeric	Any Retry event
{MAX_ATTEMPT}	Max attempt defined for the current request	Numeric	Any Retry event
{THROTTLE_LIMIT}	How many reqs/s is defined for the current request	Numeric	Any Throttle event
{THROTTLE_TIME}	How long Gracy will wait before calling the request	Numeric	Any Throttle event
{THROTTLE_TIME_RANGE}	Time range defined by the throttling rule	second, 90 seconds	Any Throttle event

and you can set up the log events as follows:

Requests

1. Before request
2. After response
3. Response has non successful errors

GracyConfig(
  log_request=LogEvent(),
  log_response=LogEvent(),
  log_errors=LogEvent(),
)

Retry

1. Before retry
2. After retry
3. When retry exhausted

GracefulRetry(
  ...,
  log_before=LogEvent(),
  log_after=LogEvent(),
  log_exhausted=LogEvent(),
)

Throttling

1. When reqs/s limit is reached
2. When limit decreases again

GracefulThrottle(
  ...,
  log_limit_reached=LogEvent()
  log_wait_over=LogEvent()
)

Dynamic Customization

You can customize it even further by passing a lambda:

LogEvent(
    LogLevel.ERROR,
    lambda r: "Request failed with {STATUS}" f" and it was {'redirected' if r.is_redirect else 'NOT redirected'}"
    if r
    else "",
)

Consider that:

• Not all log events have the response available, so you need to guard yourself against it
• Placeholders still works (e.g. {STATUS})
• You need to watch out for some attrs that might break the formatting logic (e.g. r.headers)

Custom Exceptions

You can define custom exceptions for more fine grained control over your exception messages/types.

The simplest you can do is:

from gracy import Gracy, GracyConfig
from gracy.exceptions import GracyUserDefinedException

class MyCustomException(GracyUserDefinedException):
  pass

class MyApi(Gracy[str]):
  class Config:
    SETTINGS = GracyConfig(
      ...,
      parser={
        HTTPStatus.BAD_REQUEST: MyCustomException
      }
    )

This will raise your custom exception under the conditions defined in your parser.

You can improve it even further by customizing your message:

class PokemonNotFound(GracyUserDefinedException):
    BASE_MESSAGE = "Unable to find a pokemon with the name [{NAME}] at {URL} due to {STATUS} status"

    def _format_message(self, request_context: GracyRequestContext, response: httpx.Response) -> str:
        format_args = self._build_default_args()
        name = request_context.endpoint_args.get("NAME", "Unknown")
        return self.BASE_MESSAGE.format(NAME=name, **format_args)

Reports

Logger

Recommended for production environments.

Gracy reports a short summary using logger.info.

pokeapi = GracefulPokeAPI()
# do stuff with your API
pokeapi.report_status("logger")

# OUTPUT
❯ Gracy tracked that 'https://pokeapi.co/api/v2/pokemon/{NAME}' was hit 1 time(s) with a success rate of 100.00%, avg latency of 0.45s, and a rate of 1.0 reqs/s.
❯ Gracy tracked a total of 2 requests with a success rate of 100.00%, avg latency of 0.24s, and a rate of 1.0 reqs/s.

List

Uses print to generate a short list with all attributes:

pokeapi = GracefulPokeAPI()
# do stuff with your API
pokeapi.report_status("list")

# OUTPUT
   ____
  / ___|_ __ __ _  ___ _   _
 | |  _| '__/ _` |/ __| | | |
 | |_| | | | (_| | (__| |_| |
  \____|_|  \__,_|\___|\__, |
                       |___/  Requests Summary Report


1. https://pokeapi.co/api/v2/pokemon/{NAME}
    Total Reqs (#): 1
       Success (%): 100.00%
          Fail (%): 0.00%
   Avg Latency (s): 0.39
   Max Latency (s): 0.39
         2xx Resps: 1
         3xx Resps: 0
         4xx Resps: 0
         5xx Resps: 0
      Avg Reqs/sec: 1.0 reqs/s


2. https://pokeapi.co/api/v2/generation/{ID}/
    Total Reqs (#): 1
       Success (%): 100.00%
          Fail (%): 0.00%
   Avg Latency (s): 0.04
   Max Latency (s): 0.04
         2xx Resps: 1
         3xx Resps: 0
         4xx Resps: 0
         5xx Resps: 0
      Avg Reqs/sec: 1.0 reqs/s


TOTAL
    Total Reqs (#): 2
       Success (%): 100.00%
          Fail (%): 0.00%
   Avg Latency (s): 0.21
   Max Latency (s): 0.00
         2xx Resps: 2
         3xx Resps: 0
         4xx Resps: 0
         5xx Resps: 0
      Avg Reqs/sec: 1.0 reqs/s

Table

It requires you to install Rich.

pokeapi = GracefulPokeAPI()
# do stuff with your API
pokeapi.report_status("rich")

Here's an example of how it looks:

Replay requests

Gracy allows you to replay requests and responses from previous interactions.

This is powerful because it allows you to test APIs without latency or consuming your rate limit. Now writing unit tests that relies on third-party APIs is doable.

It works in two steps:

Step	Description	Hits the API?
1. Recording	Stores all requests/responses to be later replayed	Yes
2. Replay	Returns all previously generated responses based on your request as a "replay"	No

Recording

The effort to record requests/responses is ZERO. You just need to pass a recording config to your Graceful API:

from gracy import GracyReplay
from gracy.replays.storages.sqlite import SQLiteReplayStorage

record_mode = GracyReplay("record", SQLiteReplayStorage("pokeapi.sqlite3"))
pokeapi = GracefulPokeAPI(record_mode)

Every request will be recorded to the defined data source.

Replay

Once you have recorded all your requests you can enable the replay mode:

from gracy import GracyReplay
from gracy.replays.storages.sqlite import SQLiteReplayStorage

replay_mode = GracyReplay("replay", SQLiteReplayStorage("pokeapi.sqlite3"))
pokeapi = GracefulPokeAPI(replay_mode)

Every request will be routed to the defined data source resulting in faster responses.

⚠️ Note that parsers, retries, throttling, and similar configs will work as usual.

Advanced Usage

Customizing/Overriding configs per method

APIs may return different responses/conditions/payloads based on the endpoint.

You can override any GracyConfig on a per method basis by using the @graceful decorator.

NOTE: Use @graceful_generator if your function uses yield.

from gracy import Gracy, GracyConfig, GracefulRetry, graceful, graceful_generator

retry = GracefulRetry(...)

class GracefulPokeAPI(Gracy[PokeApiEndpoint]):
    class Config:  # type: ignore
        BASE_URL = "https://pokeapi.co/api/v2/"
        SETTINGS = GracyConfig(
            retry=retry,
            log_errors=LogEvent(
                LogLevel.ERROR, "How can I become a pokemon master if {URL} keeps failing with {STATUS}"
            ),
        )

    @graceful(
        retry=None, # 👈 Disables retry set in Config
        log_errors=None, # 👈 Disables log_errors set in Config
        allowed_status_code=HTTPStatus.NOT_FOUND,
        parser={
            "default": lambda r: r.json()["order"],
            HTTPStatus.NOT_FOUND: None,
        },
    )
    async def maybe_get_pokemon_order(self, name: str):
        val: str | None = await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})
        return val

    @graceful( # 👈 Retry and log_errors are still set for this one
      strict_status_code=HTTPStatus.OK,
      parser={"default": lambda r: r.json()["order"]},
    )
    async def get_pokemon_order(self, name: str):
      val: str = await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})
      return val

    @graceful_generator( # 👈 Retry and log_errors are still set for this one
      parser={"default": lambda r: r.json()["order"]},
    )
    async def get_2_pokemons(self):
      names = ["charmander", "pikachu"]

      for name in names:
          r = await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})
          yield r

Customizing HTTPx client

You might want to modify the HTTPx client settings, do so by:

class YourAPIClient(Gracy[str]):
    class Config:  # type: ignore
        ...

    def __init__(self, token: token) -> None:
        self._token = token
        super().__init__()

    # 👇 Implement your logic here
    def _create_client(self) -> httpx.AsyncClient:
        client = super()._create_client()
        client.headers = {"Authorization": f"token {self._token}"}  # type: ignore
        return client

Overriding default request timeout

As default Gracy won't enforce a request timeout.

You can define your own by setting it on Config as:

class GracefulAPI(GracyApi[str]):
  class Config:
    BASE_URL = "https://example.com"
    REQUEST_TIMEOUT = 10.2  # 👈 Here

Creating a custom Replay data source

Gracy was built with extensibility in mind.

You can create your own storage to store/load anywhere (e.g. SQL Database), here's an example:

import httpx
from gracy import GracyReplayStorage

class MyCustomStorage(GracyReplayStorage):
  def prepare(self) -> None: # (Optional) Executed upon API instance creation.
    ...

  async def record(self, response: httpx.Response) -> None:
    ... # REQUIRED. Your logic to store the response object. Note the httpx.Response has request data.

  async def _load(self, request: httpx.Request) -> httpx.Response:
    ... # REQUIRED. Your logic to load a response object based on the request.


# Usage
record_mode = GracyReplay("record", MyCustomStorage())
replay_mode = GracyReplay("replay", MyCustomStorage())

pokeapi = GracefulPokeAPI(record_mode)

Hooks before/after request

You can set up hooks simply by defining async def before and async def after methods.

⚠️ NOTE: Gracy configs are disabled within these methods which means that retries/parsers/throttling won't take effect inside it.

class GracefulPokeAPI(Gracy[PokeApiEndpoint]):
    class Config:  # type: ignore
        BASE_URL = "https://pokeapi.co/api/v2/"
        SETTINGS = GracyConfig(
            retry=RETRY,
            allowed_status_code={HTTPStatus.NOT_FOUND},
            parser={HTTPStatus.NOT_FOUND: None},
        )

    def __init__(self, *args: t.Any, **kwargs: t.Any) -> None:
        self.before_count = 0

        self.after_status_counter = defaultdict[HTTPStatus, int](int)
        self.after_aborts = 0
        self.after_retries_counter = 0

        super().__init__(*args, **kwargs)

    async def before(self, context: GracyRequestContext):
        self.before_count += 1

    async def after(
        self,
        context: GracyRequestContext, # Current request context
        response_or_exc: httpx.Response | Exception,  # Either the request or an error
        retry_state: GracefulRetryState | None,  # Set when this is generated from a retry
    ):
        if retry_state:
            self.after_retries_counter += 1

        if isinstance(response_or_exc, httpx.Response):
            self.after_status_counter[HTTPStatus(response_or_exc.status_code)] += 1
        else:
            self.after_aborts += 1

    async def get_pokemon(self, name: str):
        return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})

In the example above invoking get_pokemon() will trigger before()/after() hooks in sequence.

Common Hooks

HttpHeaderRetryAfterBackOffHook

This hook checks for 429 (TOO MANY REQUESTS), and then reads the retry-after header.

If the value is set, then Gracy pauses ALL client requests until the time is over. This behavior can be modified to happen on a per-endpoint basis if lock_per_endpoint is True.

Example Usage:

from gracy.common_hooks import HttpHeaderRetryAfterBackOffHook

class GracefulAPI(GracyAPI[Endpoint]):
  def __init__(self):
    self._retry_after_hook = HttpHeaderRetryAfterBackOffHook(
        self._reporter,
        lock_per_endpoint=True,
        log_event=LogEvent(
            LogLevel.WARNING,
            custom_message=(
                "{ENDPOINT} produced {STATUS} and requested to wait {RETRY_AFTER}s "
                "- waiting {RETRY_AFTER_ACTUAL_WAIT}s"
            ),
        ),
        # Wait +10s to avoid this from happening again too soon
        seconds_processor=lambda secs_requested: secs_requested + 10,
    )

    super().__init__()

  async def before(self, context: GracyRequestContext):
    await self._retry_after_hook.before(context)

  async def after(
    self,
    context: GracyRequestContext,
    response_or_exc: httpx.Response | Exception,
    retry_state: GracefulRetryState | None,
  ):
    retry_after_result = await self._retry_after_hook.after(context, response_or_exc)

RateLimitBackOffHook

This hook checks for 429 (TOO MANY REQUESTS) and locks requests for an arbitrary amount of time defined by you.

If the value is set, then Gracy pauses ALL client requests until the time is over. This behavior can be modified to happen on a per-endpoint basis if lock_per_endpoint is True.

from gracy.common_hooks import RateLimitBackOffHook

class GracefulAPI(GracyAPI[Endpoint]):
  def __init__(self):
    self._ratelimit_backoff_hook = RateLimitBackOffHook(
      30,
      self._reporter,
      lock_per_endpoint=True,
      log_event=LogEvent(
          LogLevel.INFO,
          custom_message="{UENDPOINT} got rate limited, waiting for {WAIT_TIME}s",
      ),
    )

    super().__init__()

  async def before(self, context: GracyRequestContext):
    await self._ratelimit_backoff_hook.before(context)

  async def after(
    self,
    context: GracyRequestContext,
    response_or_exc: httpx.Response | Exception,
    retry_state: GracefulRetryState | None,
  ):
    backoff_result = await self._ratelimit_backoff_hook.after(context, response_or_exc)

from gracy.common_hooks import HttpHeaderRetryAfterBackOffHook, RateLimitBackOffHook

📚 Extra Resources

Some good practices I learned over the past years guided Gracy's philosophy, you might benefit by reading:

• How to log
• How to handle exceptions
  • How to structure exceptions
• How to use Async correctly
• Book: Python like a PRO
• Book: Effective Python

Change log

See CHANGELOG.

License

MIT

Credits

Thanks to the last three startups I worked which forced me to do the same things and resolve the same problems over and over again. I got sick of it and built this lib.

Most importantly: Thanks to God, who allowed me (a random 🇧🇷 guy) to work for many different 🇺🇸 startups. This is ironic since due to God's grace, I was able to build Gracy. 🙌

Also, thanks to the httpx and rich projects for the beautiful and simple APIs that powers Gracy.