AWS X-Ray Remote Sampler Part 1 - Initial Rules Poller Implementation

[jj22ee]

Issue #, if available:
First PR of 3 parts for adding the X-Ray remote sampling support for OTel Python SDK.

Description of changes:

• Python Classes
  • AwsXRayRemoteSampler - extends opentelemetry.sdk.trace.sampling.Sampler and implements should_sample.
    • Upon initialization, starts polling for sampling rules by scheduling a threading.Timer to execute a poll after a configurable interval of time. After this interval, it will repeat this process indefinitely by scheduling the same threading.Timer upon completion of the previous timer.
    • OTel resource, Collector endpoint, rules polling_interval are configurable.
  • AwsXRaySamplingClient - client to call GetSamplingRules
  • SamplingRule - Class for SamplingRules type

Testing Script to poll Sampling Rules every 5 seconds:

import logging
import time

from amazon.opentelemetry.distro.sampler.aws_xray_remote_sampler import AwsXRayRemoteSampler
from opentelemetry.sdk.resources import Resource

logging.basicConfig(level=logging.INFO)
sampler = AwsXRayRemoteSampler(Resource.get_empty(), polling_interval=5)

time.sleep(15)

Output:

88665a53c0dd:sampler jjllee$ python3 mytesting.py 
INFO:amazon.opentelemetry.distro.sampler.aws_xray_remote_sampler:Got Sampling Rules: {'[{"Attributes": {}, "FixedRate": 0.05, "HTTPMethod": "*", "Host": "*", "Priority": 10000, "ReservoirSize": 100, "ResourceARN": "*", "RuleARN": "arn:aws:xray:us-east-1:999999999999:sampling-rule/Default", "RuleName": "Default", "ServiceName": "*", "ServiceType": "*", "URLPath": "*", "Version": 1}, {"Attributes": {"abc": "1234"}, "FixedRate": 0.11, "HTTPMethod": "*", "Host": "*", "Priority": 20, "ReservoirSize": 1, "ResourceARN": "*", "RuleARN": "arn:aws:xray:us-east-1:999999999999:sampling-rule/test", "RuleName": "test", "ServiceName": "*", "ServiceType": "*", "URLPath": "*", "Version": 1}]'}
INFO:amazon.opentelemetry.distro.sampler.aws_xray_remote_sampler:Got Sampling Rules: {'[{"Attributes": {}, "FixedRate": 0.05, "HTTPMethod": "*", "Host": "*", "Priority": 10000, "ReservoirSize": 100, "ResourceARN": "*", "RuleARN": "arn:aws:xray:us-east-1:999999999999:sampling-rule/Default", "RuleName": "Default", "ServiceName": "*", "ServiceType": "*", "URLPath": "*", "Version": 1}, {"Attributes": {"abc": "1234"}, "FixedRate": 0.11, "HTTPMethod": "*", "Host": "*", "Priority": 20, "ReservoirSize": 1, "ResourceARN": "*", "RuleARN": "arn:aws:xray:us-east-1:999999999999:sampling-rule/test", "RuleName": "test", "ServiceName": "*", "ServiceType": "*", "URLPath": "*", "Version": 1}]'}
INFO:amazon.opentelemetry.distro.sampler.aws_xray_remote_sampler:Got Sampling Rules: {'[{"Attributes": {}, "FixedRate": 0.05, "HTTPMethod": "*", "Host": "*", "Priority": 10000, "ReservoirSize": 100, "ResourceARN": "*", "RuleARN": "arn:aws:xray:us-east-1:999999999999:sampling-rule/Default", "RuleName": "Default", "ServiceName": "*", "ServiceType": "*", "URLPath": "*", "Version": 1}, {"Attributes": {"abc": "1234"}, "FixedRate": 0.11, "HTTPMethod": "*", "Host": "*", "Priority": 20, "ReservoirSize": 1, "ResourceARN": "*", "RuleARN": "arn:aws:xray:us-east-1:999999999999:sampling-rule/test", "RuleName": "test", "ServiceName": "*", "ServiceType": "*", "URLPath": "*", "Version": 1}]'}
88665a53c0dd:sampler jjllee$ 

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[srprash]

In the PR description can you also post the output from your testing script?

[srprash]

Also, I didn't go through the unit tests in this pass. Will review them some time soon.

[jj22ee]

Pending #36 to fix failing checks

[srprash]

Minor comments regarding the types of SamplingRule properties. Since typing in python is very fluid, it can easily lead to confusion and possible bugs if we don't treat the properties with correct types.