test_logger.py

import inspect
import io
import json
import logging
from collections import namedtuple

import pytest

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.logging.exceptions import InvalidLoggerSamplingRateError
from aws_lambda_powertools.logging.logger import set_package_logger


@pytest.fixture
def stdout():
    return io.StringIO()


@pytest.fixture
def lambda_context():
    lambda_context = {
        "function_name": "test",
        "memory_limit_in_mb": 128,
        "invoked_function_arn": "arn:aws:lambda:eu-west-1:809313241:function:test",
        "aws_request_id": "52fdfc07-2182-154f-163f-5f0f9a621d72",
    }

    return namedtuple("LambdaContext", lambda_context.keys())(*lambda_context.values())


@pytest.fixture
def lambda_event():
    return {"greeting": "hello"}


def capture_logging_output(stdout):
    return json.loads(stdout.getvalue().strip())


def capture_multiple_logging_statements_output(stdout):
    return [json.loads(line.strip()) for line in stdout.getvalue().split("\n") if line]


def test_setup_service_name(stdout):
    service_name = "payment"
    # GIVEN Logger is initialized
    # WHEN service is explicitly defined
    logger = Logger(service=service_name, stream=stdout)

    logger.info("Hello")

    # THEN service field should be equals service given
    log = capture_logging_output(stdout)
    assert service_name == log["service"]


def test_setup_no_service_name(stdout):
    # GIVEN Logger is initialized
    # WHEN no service is explicitly defined
    logger = Logger(stream=stdout)

    logger.info("Hello")

    # THEN service field should be "service_undefined"
    log = capture_logging_output(stdout)
    assert "service_undefined" == log["service"]


def test_setup_service_env_var(monkeypatch, stdout):
    service_name = "payment"
    # GIVEN Logger is initialized
    # WHEN service is explicitly defined via POWERTOOLS_SERVICE_NAME env
    monkeypatch.setenv("POWERTOOLS_SERVICE_NAME", service_name)
    logger = Logger(stream=stdout)

    logger.info("Hello")

    # THEN service field should be equals POWERTOOLS_SERVICE_NAME value
    log = capture_logging_output(stdout)
    assert service_name == log["service"]


def test_setup_sampling_rate_env_var(monkeypatch, stdout):
    # GIVEN Logger is initialized
    # WHEN samping rate is explicitly set to 100% via POWERTOOLS_LOGGER_SAMPLE_RATE env
    sampling_rate = "1"
    monkeypatch.setenv("POWERTOOLS_LOGGER_SAMPLE_RATE", sampling_rate)
    logger = Logger(stream=stdout)
    logger.debug("I am being sampled")

    # THEN sampling rate should be equals POWERTOOLS_LOGGER_SAMPLE_RATE value
    # log level should be DEBUG
    # and debug log statements should be in stdout
    log = capture_logging_output(stdout)
    assert sampling_rate == log["sampling_rate"]
    assert "DEBUG" == log["level"]
    assert "I am being sampled" == log["message"]


def test_inject_lambda_context(lambda_context, stdout):
    # GIVEN Logger is initialized
    logger = Logger(stream=stdout)

    # WHEN a lambda function is decorated with logger
    @logger.inject_lambda_context
    def handler(event, context):
        logger.info("Hello")

    handler({}, lambda_context)

    # THEN lambda contextual info should always be in the logs
    log = capture_logging_output(stdout)
    expected_logger_context_keys = (
        "function_name",
        "function_memory_size",
        "function_arn",
        "function_request_id",
    )
    for key in expected_logger_context_keys:
        assert key in log


def test_inject_lambda_context_log_event_request(lambda_context, stdout, lambda_event):
    # GIVEN Logger is initialized
    logger = Logger(stream=stdout)

    # WHEN a lambda function is decorated with logger instructed to log event
    @logger.inject_lambda_context(log_event=True)
    def handler(event, context):
        logger.info("Hello")

    handler(lambda_event, lambda_context)

    # THEN logger should log event received from Lambda
    logged_event, _ = capture_multiple_logging_statements_output(stdout)
    assert logged_event["message"] == lambda_event


def test_inject_lambda_context_log_event_request_env_var(monkeypatch, lambda_context, stdout, lambda_event):
    # GIVEN Logger is initialized
    monkeypatch.setenv("POWERTOOLS_LOGGER_LOG_EVENT", "true")
    logger = Logger(stream=stdout)

    # WHEN a lambda function is decorated with logger instructed to log event
    # via POWERTOOLS_LOGGER_LOG_EVENT env
    @logger.inject_lambda_context
    def handler(event, context):
        logger.info("Hello")

    handler(lambda_event, lambda_context)

    # THEN logger should log event received from Lambda
    logged_event, _ = capture_multiple_logging_statements_output(stdout)
    assert logged_event["message"] == lambda_event


def test_inject_lambda_context_log_no_request_by_default(monkeypatch, lambda_context, stdout, lambda_event):
    # GIVEN Logger is initialized
    logger = Logger(stream=stdout)

    # WHEN a lambda function is decorated with logger
    @logger.inject_lambda_context
    def handler(event, context):
        logger.info("Hello")

    handler(lambda_event, lambda_context)

    # THEN logger should not log event received by lambda handler
    log = capture_logging_output(stdout)
    assert log["message"] != lambda_event


def test_inject_lambda_cold_start(lambda_context, stdout):
    # cold_start can be false as it's a global variable in Logger module
    # so we reset it to simulate the correct behaviour
    # since Lambda will only import our logger lib once per concurrent execution
    from aws_lambda_powertools.logging import logger

    logger.is_cold_start = True

    # GIVEN Logger is initialized
    logger = Logger(stream=stdout)

    # WHEN a lambda function is decorated with logger, and called twice
    @logger.inject_lambda_context
    def handler(event, context):
        logger.info("Hello")

    handler({}, lambda_context)
    handler({}, lambda_context)

    # THEN cold_start key should only be true in the first call
    first_log, second_log = capture_multiple_logging_statements_output(stdout)
    assert first_log["cold_start"] is True
    assert second_log["cold_start"] is False


def test_package_logger_stream(stdout):
    # GIVEN package logger "aws_lambda_powertools" is explicitly set with no params
    set_package_logger(stream=stdout)

    # WHEN Tracer is initialized in disabled mode
    Tracer(disabled=True)

    # THEN Tracer debug log statement should be logged
    output = stdout.getvalue()
    logger = logging.getLogger("aws_lambda_powertools")
    assert "Tracing has been disabled" in output
    assert logger.level == logging.DEBUG


def test_package_logger_format(capsys):
    # GIVEN package logger "aws_lambda_powertools" is explicitly
    # with a custom formatter
    formatter = logging.Formatter("message=%(message)s")
    set_package_logger(formatter=formatter)

    # WHEN Tracer is initialized in disabled mode
    Tracer(disabled=True)

    # THEN Tracer debug log statement should be logged using `message=` format
    output = capsys.readouterr().out
    logger = logging.getLogger("aws_lambda_powertools")
    assert "message=" in output
    assert logger.level == logging.DEBUG


def test_logger_append_duplicated(stdout):
    # GIVEN Logger is initialized with request_id field
    logger = Logger(stream=stdout, request_id="value")

    # WHEN `request_id` is appended to the existing structured log
    # using a different value
    logger.structure_logs(append=True, request_id="new_value")
    logger.info("log")

    # THEN subsequent log statements should have the latest value
    log = capture_logging_output(stdout)
    assert "new_value" == log["request_id"]


def test_logger_invalid_sampling_rate():
    # GIVEN Logger is initialized
    # WHEN sampling_rate non-numeric value
    # THEN we should raise InvalidLoggerSamplingRateError
    with pytest.raises(InvalidLoggerSamplingRateError):
        Logger(stream=stdout, sampling_rate="TEST")


def test_inject_lambda_context_with_structured_log(lambda_context, stdout):
    # GIVEN Logger is initialized
    logger = Logger(stream=stdout)

    # WHEN structure_logs has been used to add an additional key upfront
    # and a lambda function is decorated with logger.inject_lambda_context
    logger.structure_logs(append=True, additional_key="test")

    @logger.inject_lambda_context
    def handler(event, context):
        logger.info("Hello")

    handler({}, lambda_context)

    # THEN lambda contextual info should always be in the logs
    log = capture_logging_output(stdout)
    expected_logger_context_keys = (
        "function_name",
        "function_memory_size",
        "function_arn",
        "function_request_id",
        "additional_key",
    )
    for key in expected_logger_context_keys:
        assert key in log


def test_logger_children_propagate_changes(stdout):
    # GIVEN Loggers are initialized
    # create child logger before parent to mimick
    # importing logger from another module/file
    # as loggers are created in global scope
    child = Logger(stream=stdout, service="order", child=True)
    parent = Logger(stream=stdout, service="order")

    # WHEN a child Logger adds an additional key
    child.structure_logs(append=True, customer_id="value")

    # THEN child Logger changes should propagate to parent
    # and subsequent log statements should have the latest value
    parent.info("Hello parent")
    child.info("Hello child")

    parent_log, child_log = capture_multiple_logging_statements_output(stdout)
    assert "customer_id" in parent_log
    assert "customer_id" in child_log
    assert child.parent.name == "order"


def test_logger_child_not_set_returns_same_logger():
    # GIVEN two Loggers are initialized with the same service name
    # WHEN child param isn't set
    logger_one = Logger(service="something")
    logger_two = Logger(service="something")

    # THEN we should have two Logger instances
    # however inner logger wise should be the same
    assert id(logger_one) != id(logger_two)
    assert logger_one._logger is logger_two._logger
    assert logger_one.name is logger_two.name


def test_logger_level_case_insensitive():
    # GIVEN a Loggers is initialized
    # WHEN log level is set as "info" instead of "INFO"
    logger = Logger(level="info")

    # THEN we should correctly set log level as INFO
    assert logger.level == logging.INFO


def test_logger_level_not_set():
    # GIVEN a Loggers is initialized
    # WHEN no log level was passed
    logger = Logger()

    # THEN we should default to INFO
    assert logger.level == logging.INFO


def test_logger_level_as_int():
    # GIVEN a Loggers is initialized
    # WHEN log level is int
    logger = Logger(level=logging.INFO)

    # THEN we should be expected int (20, in this case)
    assert logger.level == logging.INFO


def test_logger_level_env_var_as_int(monkeypatch):
    # GIVEN Logger is initialized
    # WHEN log level is explicitly defined via LOG_LEVEL env as int
    # THEN Logger should propagate ValueError
    # since env vars can only be string
    # and '50' is not a correct log level
    monkeypatch.setenv("LOG_LEVEL", 50)
    with pytest.raises(ValueError, match="Unknown level: '50'"):
        Logger()


def test_logger_record_caller_location(stdout):
    # GIVEN Logger is initialized
    logger = Logger(stream=stdout)

    # WHEN log statement is run
    logger.info("log")

    # THEN 'location' field should have
    # the correct caller resolution
    caller_fn_name = inspect.currentframe().f_code.co_name
    log = capture_logging_output(stdout)
    assert caller_fn_name in log["location"]


def test_logger_do_not_log_twice_when_root_logger_is_setup(stdout):
    # GIVEN Lambda configures the root logger with a handler
    root_logger = logging.getLogger()
    root_logger.addHandler(logging.StreamHandler(stream=stdout))

    # WHEN we create a new Logger and child Logger
    logger = Logger(stream=stdout)
    child_logger = Logger(child=True, stream=stdout)
    logger.info("hello")
    child_logger.info("hello again")

    # THEN it should only contain only two log entries
    # since child's log records propagated to root logger should be rejected
    logs = list(stdout.getvalue().strip().split("\n"))
    assert len(logs) == 2