Initial commit

contains:
* Actual template
* Example function
* Tests
* Integration test (make file)
* Integration tests (deployed as lambda)
* drone CI and CI scripts

.drone.yml

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+---
+kind: pipeline
+type: docker
+name: default
+
+steps:
+  - name: deploy-ci
+    image: python:latest
+    commands:
+      - ci/deploy.sh
+    when:
+      branch:
+        exclude:
+          - master
+
+  - name: deploy-prod
+    image: python:latest
+    commands:
+      - make all env=prod
+    when:
+      branch:
+        - master
+      event:
+        - push
+
+  - name: cleanup-env
+    image: python:latest
+    commands:
+      - ci/cleanup.sh

.gitignore

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+*.pyc
+.*-generated.yaml
+*.kate-swp
+test-response.json
+.coverage
+environments/prod.env

.yamllint.yaml

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+---
+extends: default
+
+rules:
+  line-length:
+    max: 120

LICENSE

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+Copyright 2020 Juan Canham 
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

Makefile

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+.PHONY: help all install lint clean test deploy integration-test delete
+
+ifdef $(env)
+	include environments/$(env).env
+endif
+
+CFN         := cloudformation
+CFN_NAME    := example-cloud-function
+BUCKET      := $(shell aws s3 ls | grep templates | cut -c 24-)
+TEST_DATA   := 100
+TEST_RESULT := "2,4,5,10,20,25,50"
+EMAIL       := "cv@juancanham.com"
+
+help:
+	@echo  'Targets:'
+	@echo  ' * all [install clean lint test deploy integration-test]'
+	@echo  ' * delete'
+	@echo  '   - optionally you can specify an env to load overrides'
+
+all: install clean lint test deploy integration-test
+
+install:
+	pip install -r requirements.txt
+
+clean:
+	rm -f */**/*.pyc
+	rm -f $(CFN)/.*-generated.yaml
+	rm -f test-response.txt
+
+lint:
+	yamllint .
+	black .
+	pylint --disable line-too-long src/ tests/
+	cfn-lint $(CFN)/*.yaml
+	shellcheck ci/*.sh
+
+test:
+	pytest 
+
+deploy:
+	aws cloudformation package \
+		--template-file $(CFN)/lambda-sam-template.yaml \
+		--s3-bucket $(BUCKET) \
+		--output-template-file $(CFN)/.$(CFN_NAME)-generated.yaml
+
+	aws cloudformation deploy \
+		--stack-name $(CFN_NAME) \
+		--template-file $(CFN)/.$(CFN_NAME)-generated.yaml \
+		--capabilities CAPABILITY_IAM \
+		--parameter-overrides \
+			NotificationEmail=$(EMAIL) \
+			TestData=$(TEST_DATA) \
+			TestExpected=$(TEST_RESULT)
+
+delete:
+	aws cloudformation delete-stack --stack-name $(CFN_NAME)
+
+integration-test:
+	aws lambda invoke \
+		--payload $(TEST_DATA)
+		--log-type Tail \
+		--function-name $$(aws cloudformation describe-stacks \
+			--stack-name $(CFN_NAME) \
+			--output text \
+			--query 'Stacks[0].Outputs[?OutputKey==`LambdaArn`].OutputValue' \
+		) \
+		test-response.txt
+	grep $(TEST_RESULT) test-response.txt

README.md

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+# Overview
+
+A simple example project to use SAM/CodeDeploy preTrafficHooks
+to validate a lambda before finishing the deployment
+
+## Install, Linting, Testing, Deploying, Integration-Testing
+
+* Code uses black for formatting and pylint for code-standards
+* Tests use pytest
+* Deployment uses cloudformation via [SAM] for simplification
+* Integration Tests are part of the cloudformation
+
+See `make help` for more details
+
+### Deployment
+
+Environment overrides can be written in environments/<env>.vars
+then launched with `make all env=<env>`
+
+#### CI
+
+This folder has scripts to
+
+* Deploy and Delete a CI environment
+* Deploy a permanent environment based on environments/<env>
+* Cleanup environments after merging
+
+## Contributing
+
+Before contributing, please run all tests in a clean environment,
+e.g run `make all`
+
+[SAM]: https://github.com/awsdocs/aws-sam-developer-guide/blob/master/doc_source/sam-specification.md

ci/cleanup.sh

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+#!/usr/bin/env bash
+# Delete a deployed environment after a merge
+# checks parent commits for environment/<env>.env
+
+PROTECTED=master
+
+function try_and_delete_environment () {
+  if [ -f "environments/${1}.env" ]; then
+    make delete env="${1}"
+    exit 0
+  fi
+}
+
+MERGED_ENVIRONMENT="${DRONE_SOURCE_BRANCH##*/}"
+if [[ ! "$MERGED_ENVIRONMENT" =~ $PROTECTED ]]; then
+  try_and_delete_environment "$MERGED_ENVIRONMENT"
+
+  echo "Checking out parent commits for env file"
+  for PARENT in $(git log --pretty=%P -n 1 | tac -s ' '); do
+    git checkout "$PARENT"
+    try_and_delete_environment "$MERGED_ENVIRONMENT"
+  done
+fi

ci/deploy.sh

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+#!/usr/bin/env bash
+PROTECTED=master
+
+ENVIRONMENT="${DRONE_BRANCH##*/}"
+[ -z "$ENVIRONMENT" ] && ENVIRONMENT="$DRONE_TAG"
+
+if [[ "$ENVIRONMENT" =~ $PROTECTED ]] && [ "$ENVIRONMENT" != "$DRONE_BRANCH" ] ; then
+  echo "Can only deploy to $PROTECTED from named branches"
+  unset ENVIRONMENT
+fi
+
+if [ -f "environments/${ENVIRONMENT}.env" ] ; then
+  make all "env=${ENVIRONMENT}"
+else
+  make all env=ci
+  make delete env=ci
+fi

cloudformation/lambda-sam-template.yaml

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+---
+AWSTemplateFormatVersion: 2010-09-09
+Transform: AWS::Serverless-2016-10-31
+Description: An Lambda function with a monitoring alarm, DLQ & PreTraffic Test
+Metadata:
+  License: magnet:?xt=urn:btih:1f739d935676111cfff4b4693e3816e664797050&dn=gpl-3.0.txt GPL-v3-or-Later
+  cfn-lint:
+    config:
+      ignore_checks:
+        - W3011  # UpdatePolicy generated by SAM
+
+Parameters:
+  NotificationEmail:
+    Type: String
+  TestData:
+    Type: String
+  TestExpected:
+    Type: String
+
+Resources:
+  Function:
+    Type: AWS::Serverless::Function
+    Properties:
+      Handler: lambda_function.handler
+      Runtime: python3.7
+      CodeUri: src/lambda_function.py
+      DeadLetterQueue:
+        TargetArn: !GetAtt DeadLetterQueue.Arn
+        Type: SQS
+      AutoPublishAlias: live
+      DeploymentPreference:
+        Type: CodeDeployDefault.LambdaAllAtOnce
+        Alarms:
+          - !Ref Alarm
+        Hooks:
+          PreTraffic: !Ref TestFunction
+
+
+  Alarm:
+    Type: AWS::CloudWatch::Alarm
+    Properties:
+      ActionsEnabled: true
+      AlarmActions:
+        - !Ref NotificationTopic
+      AlarmDescription: Notify on failures of cloud-interest-rate-calculator function
+      AlarmName: !Sub ${AWS::StackName}-errors
+      MetricName: Errors
+      Namespace: AWS/Lambda
+      Statistic: Sum
+      Dimensions:
+        - Name: FunctionName
+          Value: !Select [6, !Split [':', !GetAtt Function.Arn]]
+        - Name: Resource
+          Value: !Select [6, !Split [':', !GetAtt Function.Arn]]
+      Period: 300
+      EvaluationPeriods: 1
+      DatapointsToAlarm: 1
+      Threshold: 0
+      ComparisonOperator: GreaterThanThreshold
+
+  NotificationTopic:
+    Type: AWS::SNS::Topic
+    Properties:
+      DisplayName: !Sub ${AWS::StackName}-errors
+      Subscription:
+        - Endpoint: !Ref NotificationEmail
+          Protocol: email
+      Tags:
+        - Key: Type
+          Value: Monitoring
+
+  DeadLetterQueue:
+    Type: AWS::SQS::Queue
+    Properties:
+      Tags:
+        - Key: Type
+          Value: DeadLetterQueue
+
+  TestFunction:
+    Type: AWS::Serverless::Function
+    Properties:
+      FunctionName: !Sub CodeDeployHook_PreHook_${AWS::StackName}
+      Handler: lambda_verification.handler
+      Runtime: python3.7
+      CodeUri: src/lambda_verification.py
+      Environment:
+        Variables:
+          CurrentVersion: !Ref Function.Version
+          TestData: !Ref TestData
+          TestExpected: !Ref TestExpected
+      Policies:
+        - Version: 2012-10-17
+          Statement:
+            - Effect: Allow
+              Action: codedeploy:PutLifecycleEventHookExecutionStatus
+              Resource: "*"
+            - Effect: Allow
+              Action: lambda:InvokeFunction
+              Resource: !Sub "${Function.Arn}:*"
+
+Outputs:
+  LambdaArn:
+    Value: !GetAtt Function.Arn

environments/ci.env

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+CFN_NAME = example-cloud-function-ci-$(git rev-parse HEAD | cut -c 1-8)

requirements.txt

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+awscli==1.*
+black==19.10b0
+cfn-lint==0.28.*
+mock==4.*
+pylint==2.*
+pytest==5.*
+yamllint==1.20.*
+pytest-cov==2.8.*
+shellcheck-py==0.7.*

src/lambda_function.py

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+""" An Simple example lambda"""
+from typing import Set
+
+# pylint: disable=unused-argument
+def handler(event, context):
+    """
+    Lambda event handler takes a number and returns it's factors
+
+    event must have an value key which can be cast to an int
+
+    return value is a comma separated list of numbers as a string
+  """
+    try:
+        value = int(event["value"])
+    except Exception as error:
+        print(f"Failure\tFailed to read value\t{error}\t{event}")
+        raise error
+    try:
+        factors = get_factors(value)
+        response = stringify(factors)
+        print(f"Success\tCalculated\t{value}\t{response}")
+        return response
+    except Exception as error:
+        print(f"Failure\tFailed to calculate response\t{error}\t{value}")
+        raise error
+
+
+def get_factors(number: int) -> Set[int]:
+    """ Calculate factors of an integer """
+    result = set()
+    for i in range(1, int(number ** 0.5) + 1):
+        div, mod = divmod(number, i)
+        if mod == 0:
+            result.add(i)
+            result.add(div)
+    return result
+
+
+def stringify(numbers: Set[int]) -> str:
+    """ Convert a list of numbers to an order comma separated list """
+    numbers = list(numbers)
+    numbers.sort()
+    numbers = [str(i) for i in numbers]
+    response = ",".join(numbers)
+    return response

src/lambda_verification.py

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+""" Generic lambda function tester that uses environmental variables """
+# pylint: disable=broad-except
+import os
+import boto3
+
+AWSLAMBDA = boto3.client("lambda")
+CODEDEPLOY = boto3.client("codedeploy")
+
+# pylint: disable=unused-argument
+def handler(event, context):
+    """ Entry point for test """
+    try:
+        function = os.environ["CurrentVersion"]
+        expected = os.environ["TestExpected"]
+        payload = os.environ["TestData"]
+
+        codedeploy_params = {
+            "deploymentId": event["DeploymentId"],
+            "lifecycleEventHookExecutionId": event["LifecycleEventHookExecutionId"],
+            "status": "Failed",
+        }
+    except Exception as error:
+        print(f"Exception, failed to unpack event, {function}, {error}, event, {event}")
+        raise error
+
+    try:
+        print(f"Info, testing, {function}, {payload}")
+        response = AWSLAMBDA.invoke(FunctionName=function, Payload=payload)
+        response_value = response["Payload"].read()
+    except Exception as error:
+        print(f"Failed, invocation failed, {function}, {error}")
+        CODEDEPLOY.put_lifecycle_event_hook_execution_status(**codedeploy_params)
+        return
+
+    try:
+        assert response_value == expected
+    except Exception as error:
+        print(
+            f"Failed, incorrect response, {function}, {error}, expected, {expected}, actual, {response}"
+        )
+        CODEDEPLOY.put_lifecycle_event_hook_execution_status(**codedeploy_params)
+        return
+
+    try:
+        print(f"Success, notifying codedeploy, {function}, {event['DeploymentId']}")
+        codedeploy_params["status"] = "Succeeded"
+        CODEDEPLOY.put_lifecycle_event_hook_execution_status(**codedeploy_params)
+        return
+    except Exception as error:
+        print(f"Exception, failed to notify codedeploy, {function}, {error}")
+        raise error

tests/test_lambda_function.py

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+""" Tests for cloud_interest_rate_calculator """
+# pylint: disable=no-self-use,missing-function-docstring,missing-class-docstring
+
+import pytest
+import mock
+from src import lambda_function
+
+
+class TestExampleFunction:
+    @pytest.mark.parametrize("event", [{"value": "One Thousand"}, {"not_value": 1000}])
+    def test_handler_bad_input(self, event):
+        with pytest.raises(Exception):
+            assert lambda_function.handler(event, {})
+
+    @mock.patch("src.lambda_function.get_factors")
+    def test_handler_unexpected_error(self, mock_calculate_interest):
+        event = {"value": "10"}
+        mock_calculate_interest.side_effect = Exception()
+        with pytest.raises(Exception):
+            assert lambda_function.handler(event, {})
+
+    def test_handler(self):
+        event = {"value": "10"}
+        response = lambda_function.handler(event, {})
+        assert response == "1,2,5,10"
+
+    @pytest.mark.parametrize(
+        "initial,expected",
+        [
+            (1, {1}),
+            (10, {1, 2, 5, 10}),
+            (60, {1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60}),
+            (64, {1, 2, 4, 8, 16, 32, 64}),
+        ],
+    )
+    def test_get_factors(self, initial, expected):
+        response = lambda_function.get_factors(initial)
+        assert response == expected
+
+    @pytest.mark.parametrize(
+        "initial,expected",
+        [([], ""), ([1], "1"), ([2], "2"), ([1, 2, 3], "1,2,3"), ([1, 3, 2], "1,2,3"),],
+    )
+    def test_stringify(self, initial, expected):
+        response = lambda_function.stringify(initial)
+        assert response == expected

tests/test_lambda_verification.py

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+""" Tests for lambda_verification function """
+# pylint: disable=no-self-use,missing-function-docstring,missing-class-docstring
+
+import os
+import pytest
+import mock
+from src import lambda_verification
+
+PAYLOAD = {
+    "DeploymentId": "TestDeployment001",
+    "LifecycleEventHookExecutionId": "LifeCycleTest001",
+}
+
+os.environ["CurrentVersion"] = "CurVer"
+os.environ["TestData"] = '{"value":"10"}'
+os.environ["TestExpected"] = "2,5"
+
+
+class TestLambdaVerfication:
+    def test_handler_bad_payload(self):
+        with pytest.raises(Exception):
+            assert lambda_verification.handler({}, {})
+
+    @mock.patch("src.lambda_verification.CODEDEPLOY")
+    @mock.patch("src.lambda_verification.AWSLAMBDA")
+    @pytest.mark.parametrize(
+        "response,expected", [("2,4", "Failed"), ("2,5", "Succeeded")],
+    )
+    def test_handler(self, mock_lambda, mock_codedeploy, response, expected):
+        response_mock = mock.MagicMock()
+        response_mock.read.return_value = response
+        mock_lambda.invoke.return_value = {"Payload": response_mock}
+
+        lambda_verification.handler(PAYLOAD, {})
+
+        mock_codedeploy.put_lifecycle_event_hook_execution_status.assert_called_with(
+            status=expected,
+            deploymentId="TestDeployment001",
+            lifecycleEventHookExecutionId="LifeCycleTest001",
+        )
+
+    @mock.patch("src.lambda_verification.CODEDEPLOY")
+    @mock.patch("src.lambda_verification.AWSLAMBDA")
+    def test_handler_lambda_failure(self, mock_lambda, mock_codedeploy):
+        mock_lambda.invoke.side_effect = Exception()
+        with pytest.raises(Exception):
+            assert lambda_verification.handler(PAYLOAD, {})
+
+        mock_codedeploy.put_lifecycle_event_hook_execution_status.assert_called_with(
+            status="Failed",
+            deploymentId="TestDeployment001",
+            lifecycleEventHookExecutionId="LifeCycleTest001",
+        )
+
+    @mock.patch("src.lambda_verification.CODEDEPLOY")
+    @mock.patch("src.lambda_verification.AWSLAMBDA")
+    def test_handler_codedeploy_failure(self, mock_lambda, mock_codedeploy):
+        response_mock = mock.MagicMock()
+        response_mock.read.return_value = "2,5"
+        mock_lambda.invoke.return_value = {"Payload": response_mock}
+        mock_codedeploy.put_lifecycle_event_hook_execution_status.side_effect = (
+            Exception()
+        )
+
+        with pytest.raises(Exception):
+            assert lambda_verification.handler(PAYLOAD, {})

tox.ini

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+[pytest]
+addopts = --cov-branch --cov-report=term-missing --cov=src --cov-fail-under=100