Python's most graceful API Client Framework
Gracy handles failures, logging, retries, throttling, parsing, and reporting for all your HTTP interactions. Gracy uses httpx under the hood.
"Let Gracy do the boring stuff while you focus on your application"
Summary
π§βπ» Get started
Installation
pip install gracy
OR
poetry add gracy
Usage
Examples will be shown using the PokeAPI.
Simple example
import asyncio
import typing as t
from gracy import BaseEndpoint, Gracy, GracyConfig, LogEvent, LogLevel
class PokeApiEndpoint(BaseEndpoint):
GET_POKEMON = "/pokemon/{NAME}"
class GracefulPokeAPI(Gracy[str]):
class Config:
BASE_URL = "https://pokeapi.co/api/v2/"
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
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.
β οΈ 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, ...),
validators=MyCustomValidator(),
)
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:
return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})
Or even customize exceptions to improve your code readability:
class PokemonNotFound(GracyUserDefinedException):
...
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]:
return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})
Parsing Typing
Because parsers allow you to dynamically parse a payload based on the status code your IDE will not identify the return type by itself.
To avoid boring typing.cast
for every method, Gracy provides typed http methods, so you can define a specific return type:
async def list(self, offset: int = 0, limit: int = 20):
params = dict(offset=offset, limit=limit)
return await self.get[ResourceList](
PokeApiEndpoint.BERRY_LIST, params=params
)
async def get_one(self, name_or_id: str | int):
return await self.get[models.Berry | None](
PokeApiEndpoint.BERRY_GET, params=dict(KEY=str(name_or_id))
)
Retry
Who doesn't hate flaky APIs? π
Yet there're many of them.
Using tenacity, backoff, retry, aiohttp_retry, and any other retry libs is NOT easy enough. π
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)
COMPLEX_RULE = ThrottleRule(
url_pattern=r".*\/pokemon\/.*",
max_requests=10,
per_time=timedelta(minutes=1, seconds=30),
)
print(COMPLEX_RULE)
Setting throttling
You can set up logging and assign rules as:
class Config:
GracyConfig(
throttling=GracefulThrottle(
rules=ThrottleRule(r".*", 2),
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,
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
- Before request
- After response
- Response has non successful errors
GracyConfig(
log_request=LogEvent(),
log_response=LogEvent(),
log_errors=LogEvent(),
)
Retry
- Before retry
- After retry
- When retry exhausted
GracefulRetry(
...,
log_before=LogEvent(),
log_after=LogEvent(),
log_exhausted=LogEvent(),
)
Throttling
- When reqs/s limit is reached
- 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()
pokeapi.report_status("logger")
β― 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.
β― 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()
pokeapi.report_status("list")
____
/ ___|_ __ __ _ ___ _ _
| | _| '__/ _` |/ __| | | |
| |_| | | | (_| | (__| |_| |
\____|_| \__,_|\___|\__, |
|___/ 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()
pokeapi.report_status("rich")
Here's an example of how it looks:

Plotly
It requires you to install plotly π and pandas πΌ.
pokeapi = GracefulPokeAPI()
plotly_fig = pokeapi.report_status("plotly")
plotly_fig.show()
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.
β οΈ Note that parsers, retries, throttling, and similar configs will work as usual.
Resource Namespacing
You can have multiple namespaces to organize your API endpoints as you wish.
To do so, you just have to inherit from GracyNamespace
and instantiate it within the GracyAPI
:
from gracy import Gracy, GracyNamespace, GracyConfig
class PokemonNamespace(GracyNamespace[PokeApiEndpoint]):
async def get_one(self, name: str):
return await self.get(PokeApiEndpoint.GET_POKEMON, {"NAME": name})
class BerryNamespace(GracyNamespace[PokeApiEndpoint]):
async def get_one(self, name: str):
return await self.get(PokeApiEndpoint.GET_BERRY, {"NAME": name})
class GracefulPokeAPI(Gracy[PokeApiEndpoint]):
class Config:
BASE_URL = "https://pokeapi.co/api/v2/"
SETTINGS = GracyConfig(
retry=RETRY,
allowed_status_code={HTTPStatus.NOT_FOUND},
parser={HTTPStatus.NOT_FOUND: None},
)
berry: BerryNamespace
pokemon: PokemonNamespace
And the usage will work as:
await pokeapi.pokemon.get_one("pikachu")
await pokeapi.berry.get_one("cheri")
Note all configs are propagated to namespaces, but namespaces can still have their own which would cause merges when instantiatedg.
There're endpoints that may require pagination. For that you can use GracyPaginator
.
For a simple case where you pass offset
and limit
, you can use GracyOffsetPaginator
:
from gracy import GracyOffsetPaginator
class BerryNamespace(GracyNamespace[PokeApiEndpoint]):
@parsed_response(ResourceList)
async def list(self, offset: int = 0, limit: int = 20):
params = dict(offset=offset, limit=limit)
return await self.get(PokeApiEndpoint.BERRY_LIST, params=params)
def paginate(self, limit: int = 20) -> GracyOffsetPaginator[ResourceList]:
return GracyOffsetPaginator[ResourceList](
gracy_func=self.list,
has_next=lambda r: bool(r["next"]) if r else True,
page_size=limit,
)
and then use it as:
async def main():
api = PokeApi()
paginator = api.berry.paginate(2)
first = await paginator.next_page()
print(first)
paginator.set_page(0)
async for page in paginator:
print(page)
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:
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,
log_errors=None,
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(
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(
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:
...
def __init__(self, token: token) -> None:
self._token = token
super().__init__()
def _create_client(self) -> httpx.AsyncClient:
client = super()._create_client()
client.headers = {"Authorization": f"token {self._token}"}
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
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:
...
async def record(self, response: httpx.Response) -> None:
...
async def _load(self, request: httpx.Request) -> httpx.Response:
...
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.
β οΈ 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:
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,
response_or_exc: httpx.Response | Exception,
retry_state: GracefulRetryState | None,
):
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
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"
),
),
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
Some good practices I learned over the past years guided Gracy's philosophy, you might benefit by reading:
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 π§π· guy) to work for many different πΊπΈ startups. This is ironic since due to God's grace, I was able to build Gracy. π
Also, thanks to the httpx and rich projects for the beautiful and simple APIs that powers Gracy.