Callout Tools

Callout Tools

Library of commonly used methods within a callout server.

callouts.python.extproc.service.callout_tools.add_body_mutation(body: str | None = None, clear_body: bool = False, clear_route_cache: bool = False) → envoy.service.ext_proc.v3.external_processor_pb2.BodyResponse

Generate a BodyResponse for incoming callouts.

body and clear_body are mutually exclusive, if body is set, clear_body will be ignored. If both body and clear_body are left as default, the incoming callout’s body will not be modified.

Parameters:

• body – Body text to replace the current body of the incomming callout.

• clear_body – If true, will clear the body of the incomming callout.

• clear_route_cache – If true, will enable clear_route_cache on the generated BodyResponse.

Returns:

A configured body mutation response with the specified modifications.

Return type:

BodyResponse

callouts.python.extproc.service.callout_tools.add_command_line_args() → ArgumentParser

Adds command line args that can be passed to the CalloutServer constructor.

Returns:

Configured argument parser with callout server options.

Return type:

argparse.ArgumentParser

callouts.python.extproc.service.callout_tools.add_header_mutation(add: list[tuple[str, str]] | None = None, remove: list[str] | None = None, clear_route_cache: bool = False, append_action: envoy.config.core.v3.base_pb2.HeaderValueOption.HeaderAppendAction | None = None) → envoy.service.ext_proc.v3.external_processor_pb2.HeadersResponse

Generate a HeadersResponse mutation for incoming callouts.

Parameters:

• add – A list of tuples representing headers to add or replace.

• remove – List of header strings to remove from the callout.

• clear_route_cache – If true, will enable clear_route_cache on the generated HeadersResponse.

• append_action – Supported actions types for header append action.

Returns:

A configured header mutation response with the specified modifications.

Return type:

HeadersResponse

callouts.python.extproc.service.callout_tools.body_contains(http_body: envoy.service.ext_proc.v3.external_processor_pb2.HttpBody, body: str) → bool

Check the body for the presence of a substring.

Parameters:

body – Body substring to look for.

Returns:

True if http_body contains expected_body, false otherwise.

callouts.python.extproc.service.callout_tools.deny_callout(context, msg: str | None = None) → None

Denies a gRPC callout, optionally logging a custom message.

Parameters:

• context (grpc.ServicerContext) – The gRPC service context.

• msg (str, optional) – Custom message to log before denying the callout. Also logged to warning. If no message is specified, defaults to “Callout DENIED.”.

Raises:

grpc.StatusCode.PERMISSION_DENIED – Always raised to deny the callout.

callouts.python.extproc.service.callout_tools.header_immediate_response(code: envoy.type.v3.http_status_pb2.StatusCode, headers: list[tuple[str, str]] | None = None, append_action: envoy.config.core.v3.base_pb2.HeaderValueOption.HeaderAppendAction | None = None) → envoy.service.ext_proc.v3.external_processor_pb2.ImmediateResponse

Creates an immediate HTTP response with specific headers and status code.

Parameters:

• code (StatusCode) – The HTTP status code to return.

• headers – Optional list of tuples (header, value) to include in the response.

• append_action – Optional action specifying how headers should be appended.

Returns:

Configured immediate response with the specified headers and status code.

Return type:

ImmediateResponse

callouts.python.extproc.service.callout_tools.headers_contain(http_headers: envoy.service.ext_proc.v3.external_processor_pb2.HttpHeaders, key: str, value: str | None = None) → bool

Check the headers for a matching key value pair.

If no value is specified, only checks for the presence of the header key.

Parameters:

• http_headers – Headers to check.

• key – Header key to find.

• value – Header value to compare.

Returns:

True if http_headers contains a match, false otherwise.