API documentation#

API documentation serves as an important reference in technical documentation. Sphinx provides many approaches to writing API documentation, from writing them manually as well as automatically generating it from docstrings in your code.

This example uses sphinx.ext.autodoc for generating the API documentation skeleton. sphinx.ext.intersphinx provides links for classes in type annotations.

.. autoclass:: urllib3.util.Retry
    :members:
    :noindex:

.. autoclass:: urllib3.util.Timeout
    :members:
    :noindex:

This is a small example from reStructuredText.
class urllib3.util.Retry(total=10, connect=None, read=None, redirect=None, status=None, other=None, allowed_methods=<object object>, status_forcelist=None, backoff_factor=0, raise_on_redirect=True, raise_on_status=True, history=None, respect_retry_after_header=True, remove_headers_on_redirect=<object object>, method_whitelist=<object object>)[source]

Retry configuration.

Each retry attempt will create a new Retry object with updated values, so they can be safely reused.

Retries can be defined as a default for a pool:

retries = Retry(connect=5, read=2, redirect=5)
http = PoolManager(retries=retries)
response = http.request('GET', 'http://example.com/')

Or per-request (which overrides the default for the pool):

response = http.request('GET', 'http://example.com/', retries=Retry(10))

Retries can be disabled by passing False:

response = http.request('GET', 'http://example.com/', retries=False)

Errors will be wrapped in MaxRetryError unless retries are disabled, in which case the causing exception will be raised.

Parameters:

  • total (int) –

    Total number of retries to allow. Takes precedence over other counts.

    Set to None to remove this constraint and fall back on other counts.

    Set to 0 to fail on the first retry.

    Set to False to disable and imply raise_on_redirect=False.

  • connect (int) –

    How many connection-related errors to retry on.

    These are errors raised before the request is sent to the remote server, which we assume has not triggered the server to process the request.

    Set to 0 to fail on the first retry of this type.

  • read (int) –

    How many times to retry on read errors.

    These errors are raised after the request was sent to the server, so the request may have side-effects.

    Set to 0 to fail on the first retry of this type.

  • redirect (int) –

    How many redirects to perform. Limit this to avoid infinite redirect loops.

    A redirect is a HTTP response with a status code 301, 302, 303, 307 or 308.

    Set to 0 to fail on the first retry of this type.

    Set to False to disable and imply raise_on_redirect=False.

  • status (int) –

    How many times to retry on bad status codes.

    These are retries made on responses, where status code matches status_forcelist.

    Set to 0 to fail on the first retry of this type.

  • other (int) –

    How many times to retry on other errors.

    Other errors are errors that are not connect, read, redirect or status errors. These errors might be raised after the request was sent to the server, so the request might have side-effects.

    Set to 0 to fail on the first retry of this type.

    If total is not set, it’s a good idea to set this to 0 to account for unexpected edge cases and avoid infinite retry loops.

  • allowed_methods (iterable) –

    Set of uppercased HTTP method verbs that we should retry on.

    By default, we only retry on methods which are considered to be idempotent (multiple requests with the same parameters end with the same state). See Retry.DEFAULT_ALLOWED_METHODS.

    Set to a False value to retry on any verb.

    Warning

    Previously this parameter was named method_whitelist, that usage is deprecated in v1.26.0 and will be removed in v2.0.

  • status_forcelist (iterable) –

    A set of integer HTTP status codes that we should force a retry on. A retry is initiated if the request method is in allowed_methods and the response status code is in status_forcelist.

    By default, this is disabled with None.

  • backoff_factor (float) –

    A backoff factor to apply between attempts after the second try (most errors are resolved immediately by a second try without a delay). urllib3 will sleep for:

    {backoff factor} * (2 ** ({number of total retries} - 1))

    seconds. If the backoff_factor is 0.1, then sleep() will sleep for [0.0s, 0.2s, 0.4s, …] between retries. It will never be longer than Retry.DEFAULT_BACKOFF_MAX.

    By default, backoff is disabled (set to 0).

  • raise_on_redirect (bool) – Whether, if the number of redirects is exhausted, to raise a MaxRetryError, or to return a response with a response code in the 3xx range.

  • raise_on_status (bool) – Similar meaning to raise_on_redirect: whether we should raise an exception, or return a response, if status falls in status_forcelist range and retries have been exhausted.

  • history (tuple) – The history of the request encountered during each call to increment(). The list is in the order the requests occurred. Each list item is of class RequestHistory.

  • respect_retry_after_header (bool) – Whether to respect Retry-After header on status codes defined as Retry.RETRY_AFTER_STATUS_CODES or not.

  • remove_headers_on_redirect (iterable) – Sequence of headers to remove from the request when a response indicating a redirect is returned before firing off the redirected request.

DEFAULT_ALLOWED_METHODS = frozenset({'DELETE', 'GET', 'HEAD', 'OPTIONS', 'PUT', 'TRACE'})

Default methods to be used for allowed_methods

DEFAULT_BACKOFF_MAX = 120

Maximum backoff time.

DEFAULT_REMOVE_HEADERS_ON_REDIRECT = frozenset({'Authorization'})

Default headers to be used for remove_headers_on_redirect

RETRY_AFTER_STATUS_CODES = frozenset({413, 429, 503})

Default status codes to be used for status_forcelist

classmethod from_int(retries, redirect=True, default=None)[source]

Backwards-compatibility for the old retries format.

get_backoff_time()[source]

Formula for computing the current backoff

Return type:

float

get_retry_after(response)[source]

Get the value of Retry-After in seconds.

increment(method=None, url=None, response=None, error=None, _pool=None, _stacktrace=None)[source]

Return a new Retry object with incremented retry counters.

Parameters:

  • response (HTTPResponse) – A response object, or None, if the server did not return a response.

  • error (Exception) – An error encountered during the request, or None if the response was received successfully.

Returns:

A new Retry object.

is_exhausted()[source]

Are we out of retries?

is_retry(method, status_code, has_retry_after=False)[source]

Is this method/status code retryable? (Based on allowlists and control variables such as the number of total retries to allow, whether to respect the Retry-After header, whether this header is present, and whether the returned status code is on the list of status codes to be retried upon on the presence of the aforementioned header)

sleep(response=None)[source]

Sleep between retry attempts.

This method will respect a server’s Retry-After response header and sleep the duration of the time requested. If that is not present, it will use an exponential backoff. By default, the backoff factor is 0 and this method will return immediately.

class urllib3.util.Timeout(total=None, connect=<object object>, read=<object object>)[source]

Timeout configuration.

Timeouts can be defined as a default for a pool:

timeout = Timeout(connect=2.0, read=7.0)
http = PoolManager(timeout=timeout)
response = http.request('GET', 'http://example.com/')

Or per-request (which overrides the default for the pool):

response = http.request('GET', 'http://example.com/', timeout=Timeout(10))

Timeouts can be disabled by setting all the parameters to None:

no_timeout = Timeout(connect=None, read=None)
response = http.request('GET', 'http://example.com/, timeout=no_timeout)
Parameters:

  • total (int, float, or None) –

    This combines the connect and read timeouts into one; the read timeout will be set to the time leftover from the connect attempt. In the event that both a connect timeout and a total are specified, or a read timeout and a total are specified, the shorter timeout will be applied.

    Defaults to None.

  • connect (int, float, or None) – The maximum amount of time (in seconds) to wait for a connection attempt to a server to succeed. Omitting the parameter will default the connect timeout to the system default, probably the global default timeout in socket.py. None will set an infinite timeout for connection attempts.

  • read (int, float, or None) –

    The maximum amount of time (in seconds) to wait between consecutive read operations for a response from the server. Omitting the parameter will default the read timeout to the system default, probably the global default timeout in socket.py. None will set an infinite timeout.

Note

Many factors can affect the total amount of time for urllib3 to return an HTTP response.

For example, Python’s DNS resolver does not obey the timeout specified on the socket. Other factors that can affect total request time include high CPU load, high swap, the program running at a low priority level, or other behaviors.

In addition, the read and total timeouts only measure the time between read operations on the socket connecting the client and the server, not the total amount of time for the request to return a complete response. For most requests, the timeout is raised because the server has not sent the first byte in the specified time. This is not always the case; if a server streams one byte every fifteen seconds, a timeout of 20 seconds will not trigger, even though the request will take several minutes to complete.

If your goal is to cut off any request after a set amount of wall clock time, consider having a second “watcher” thread to cut off a slow request.

DEFAULT_TIMEOUT = <object object>

A sentinel object representing the default timeout value

clone()[source]

Create a copy of the timeout object

Timeout properties are stored per-pool but each request needs a fresh Timeout object to ensure each one has its own start/stop configured.

Returns:

a copy of the timeout object

Return type:

Timeout

property connect_timeout

Get the value to use when setting a connection timeout.

This will be a positive float or integer, the value None (never timeout), or the default system timeout.

Returns:

Connect timeout.

Return type:

int, float, Timeout.DEFAULT_TIMEOUT or None

classmethod from_float(timeout)[source]

Create a new Timeout from a legacy timeout value.

The timeout value used by httplib.py sets the same timeout on the connect(), and recv() socket requests. This creates a Timeout object that sets the individual timeouts to the timeout value passed to this function.

Parameters:

timeout (integer, float, sentinel default object, or None) – The legacy timeout value.

Returns:

Timeout object

Return type:

Timeout

get_connect_duration()[source]

Gets the time elapsed since the call to start_connect().

Returns:

Elapsed time in seconds.

Return type:

float

Raises:

urllib3.exceptions.TimeoutStateError – if you attempt to get duration for a timer that hasn’t been started.

property read_timeout

Get the value for the read timeout.

This assumes some time has elapsed in the connection timeout and computes the read timeout appropriately.

If self.total is set, the read timeout is dependent on the amount of time taken by the connect timeout. If the connection time has not been established, a TimeoutStateError will be raised.

Returns:

Value to use for the read timeout.

Return type:

int, float, Timeout.DEFAULT_TIMEOUT or None

Raises:

urllib3.exceptions.TimeoutStateError – If start_connect() has not yet been called on this object.

start_connect()[source]

Start the timeout clock, used during a connect() attempt

Raises:

urllib3.exceptions.TimeoutStateError – if you attempt to start a timer that has been started already.

This is a small example from reStructuredText.

```{eval-rst}
.. autoclass:: urllib3.util.Retry
    :members:
    :noindex:

.. autoclass:: urllib3.util.Timeout
    :members:
    :noindex:
```

This is a small example from Markdown.
class urllib3.util.Retry(total=10, connect=None, read=None, redirect=None, status=None, other=None, allowed_methods=<object object>, status_forcelist=None, backoff_factor=0, raise_on_redirect=True, raise_on_status=True, history=None, respect_retry_after_header=True, remove_headers_on_redirect=<object object>, method_whitelist=<object object>)[source]

Retry configuration.

Each retry attempt will create a new Retry object with updated values, so they can be safely reused.

Retries can be defined as a default for a pool:

retries = Retry(connect=5, read=2, redirect=5)
http = PoolManager(retries=retries)
response = http.request('GET', 'http://example.com/')

Or per-request (which overrides the default for the pool):

response = http.request('GET', 'http://example.com/', retries=Retry(10))

Retries can be disabled by passing False:

response = http.request('GET', 'http://example.com/', retries=False)

Errors will be wrapped in MaxRetryError unless retries are disabled, in which case the causing exception will be raised.

Parameters:

  • total (int) –

    Total number of retries to allow. Takes precedence over other counts.

    Set to None to remove this constraint and fall back on other counts.

    Set to 0 to fail on the first retry.

    Set to False to disable and imply raise_on_redirect=False.

  • connect (int) –

    How many connection-related errors to retry on.

    These are errors raised before the request is sent to the remote server, which we assume has not triggered the server to process the request.

    Set to 0 to fail on the first retry of this type.

  • read (int) –

    How many times to retry on read errors.

    These errors are raised after the request was sent to the server, so the request may have side-effects.

    Set to 0 to fail on the first retry of this type.

  • redirect (int) –

    How many redirects to perform. Limit this to avoid infinite redirect loops.

    A redirect is a HTTP response with a status code 301, 302, 303, 307 or 308.

    Set to 0 to fail on the first retry of this type.

    Set to False to disable and imply raise_on_redirect=False.

  • status (int) –

    How many times to retry on bad status codes.

    These are retries made on responses, where status code matches status_forcelist.

    Set to 0 to fail on the first retry of this type.

  • other (int) –

    How many times to retry on other errors.

    Other errors are errors that are not connect, read, redirect or status errors. These errors might be raised after the request was sent to the server, so the request might have side-effects.

    Set to 0 to fail on the first retry of this type.

    If total is not set, it’s a good idea to set this to 0 to account for unexpected edge cases and avoid infinite retry loops.

  • allowed_methods (iterable) –

    Set of uppercased HTTP method verbs that we should retry on.

    By default, we only retry on methods which are considered to be idempotent (multiple requests with the same parameters end with the same state). See Retry.DEFAULT_ALLOWED_METHODS.

    Set to a False value to retry on any verb.

    Warning

    Previously this parameter was named method_whitelist, that usage is deprecated in v1.26.0 and will be removed in v2.0.

  • status_forcelist (iterable) –

    A set of integer HTTP status codes that we should force a retry on. A retry is initiated if the request method is in allowed_methods and the response status code is in status_forcelist.

    By default, this is disabled with None.

  • backoff_factor (float) –

    A backoff factor to apply between attempts after the second try (most errors are resolved immediately by a second try without a delay). urllib3 will sleep for:

    {backoff factor} * (2 ** ({number of total retries} - 1))

    seconds. If the backoff_factor is 0.1, then sleep() will sleep for [0.0s, 0.2s, 0.4s, …] between retries. It will never be longer than Retry.DEFAULT_BACKOFF_MAX.

    By default, backoff is disabled (set to 0).

  • raise_on_redirect (bool) – Whether, if the number of redirects is exhausted, to raise a MaxRetryError, or to return a response with a response code in the 3xx range.

  • raise_on_status (bool) – Similar meaning to raise_on_redirect: whether we should raise an exception, or return a response, if status falls in status_forcelist range and retries have been exhausted.

  • history (tuple) – The history of the request encountered during each call to increment(). The list is in the order the requests occurred. Each list item is of class RequestHistory.

  • respect_retry_after_header (bool) – Whether to respect Retry-After header on status codes defined as Retry.RETRY_AFTER_STATUS_CODES or not.

  • remove_headers_on_redirect (iterable) – Sequence of headers to remove from the request when a response indicating a redirect is returned before firing off the redirected request.

DEFAULT_ALLOWED_METHODS = frozenset({'DELETE', 'GET', 'HEAD', 'OPTIONS', 'PUT', 'TRACE'})

Default methods to be used for allowed_methods

DEFAULT_BACKOFF_MAX = 120

Maximum backoff time.

DEFAULT_REMOVE_HEADERS_ON_REDIRECT = frozenset({'Authorization'})

Default headers to be used for remove_headers_on_redirect

RETRY_AFTER_STATUS_CODES = frozenset({413, 429, 503})

Default status codes to be used for status_forcelist

classmethod from_int(retries, redirect=True, default=None)[source]

Backwards-compatibility for the old retries format.

get_backoff_time()[source]

Formula for computing the current backoff

Return type:

float

get_retry_after(response)[source]

Get the value of Retry-After in seconds.

increment(method=None, url=None, response=None, error=None, _pool=None, _stacktrace=None)[source]

Return a new Retry object with incremented retry counters.

Parameters:

  • response (HTTPResponse) – A response object, or None, if the server did not return a response.

  • error (Exception) – An error encountered during the request, or None if the response was received successfully.

Returns:

A new Retry object.

is_exhausted()[source]

Are we out of retries?

is_retry(method, status_code, has_retry_after=False)[source]

Is this method/status code retryable? (Based on allowlists and control variables such as the number of total retries to allow, whether to respect the Retry-After header, whether this header is present, and whether the returned status code is on the list of status codes to be retried upon on the presence of the aforementioned header)

sleep(response=None)[source]

Sleep between retry attempts.

This method will respect a server’s Retry-After response header and sleep the duration of the time requested. If that is not present, it will use an exponential backoff. By default, the backoff factor is 0 and this method will return immediately.

class urllib3.util.Timeout(total=None, connect=<object object>, read=<object object>)[source]

Timeout configuration.

Timeouts can be defined as a default for a pool:

timeout = Timeout(connect=2.0, read=7.0)
http = PoolManager(timeout=timeout)
response = http.request('GET', 'http://example.com/')

Or per-request (which overrides the default for the pool):

response = http.request('GET', 'http://example.com/', timeout=Timeout(10))

Timeouts can be disabled by setting all the parameters to None:

no_timeout = Timeout(connect=None, read=None)
response = http.request('GET', 'http://example.com/, timeout=no_timeout)
Parameters:

  • total (int, float, or None) –

    This combines the connect and read timeouts into one; the read timeout will be set to the time leftover from the connect attempt. In the event that both a connect timeout and a total are specified, or a read timeout and a total are specified, the shorter timeout will be applied.

    Defaults to None.

  • connect (int, float, or None) – The maximum amount of time (in seconds) to wait for a connection attempt to a server to succeed. Omitting the parameter will default the connect timeout to the system default, probably the global default timeout in socket.py. None will set an infinite timeout for connection attempts.

  • read (int, float, or None) –

    The maximum amount of time (in seconds) to wait between consecutive read operations for a response from the server. Omitting the parameter will default the read timeout to the system default, probably the global default timeout in socket.py. None will set an infinite timeout.

Note

Many factors can affect the total amount of time for urllib3 to return an HTTP response.

For example, Python’s DNS resolver does not obey the timeout specified on the socket. Other factors that can affect total request time include high CPU load, high swap, the program running at a low priority level, or other behaviors.

In addition, the read and total timeouts only measure the time between read operations on the socket connecting the client and the server, not the total amount of time for the request to return a complete response. For most requests, the timeout is raised because the server has not sent the first byte in the specified time. This is not always the case; if a server streams one byte every fifteen seconds, a timeout of 20 seconds will not trigger, even though the request will take several minutes to complete.

If your goal is to cut off any request after a set amount of wall clock time, consider having a second “watcher” thread to cut off a slow request.

DEFAULT_TIMEOUT = <object object>

A sentinel object representing the default timeout value

clone()[source]

Create a copy of the timeout object

Timeout properties are stored per-pool but each request needs a fresh Timeout object to ensure each one has its own start/stop configured.

Returns:

a copy of the timeout object

Return type:

Timeout

property connect_timeout

Get the value to use when setting a connection timeout.

This will be a positive float or integer, the value None (never timeout), or the default system timeout.

Returns:

Connect timeout.

Return type:

int, float, Timeout.DEFAULT_TIMEOUT or None

classmethod from_float(timeout)[source]

Create a new Timeout from a legacy timeout value.

The timeout value used by httplib.py sets the same timeout on the connect(), and recv() socket requests. This creates a Timeout object that sets the individual timeouts to the timeout value passed to this function.

Parameters:

timeout (integer, float, sentinel default object, or None) – The legacy timeout value.

Returns:

Timeout object

Return type:

Timeout

get_connect_duration()[source]

Gets the time elapsed since the call to start_connect().

Returns:

Elapsed time in seconds.

Return type:

float

Raises:

urllib3.exceptions.TimeoutStateError – if you attempt to get duration for a timer that hasn’t been started.

property read_timeout

Get the value for the read timeout.

This assumes some time has elapsed in the connection timeout and computes the read timeout appropriately.

If self.total is set, the read timeout is dependent on the amount of time taken by the connect timeout. If the connection time has not been established, a TimeoutStateError will be raised.

Returns:

Value to use for the read timeout.

Return type:

int, float, Timeout.DEFAULT_TIMEOUT or None

Raises:

urllib3.exceptions.TimeoutStateError – If start_connect() has not yet been called on this object.

start_connect()[source]

Start the timeout clock, used during a connect() attempt

Raises:

urllib3.exceptions.TimeoutStateError – if you attempt to start a timer that has been started already.

This is a small example from Markdown.