How can I use JSON logic in an AWS Cloudwatch custom event?

Question

I'm trying to get a custom event setup in AWS CloudWatch. My goal is to trigger on either:

event:pullRequestMergeStatus AND isMerged:True
OR
event:pullRequestStatusChanged AND isMerged:False

I've tried using JSOM logical operators, such as:

{"$and":[{"event":"pullRequestMergeStatus"}, {"isMerged":"True"}]}

However either AWS doesn't support that or the syntax is incorrect. I've also tried adding an array into my detail part of the JSON string, but that ends with a syntax error, and adding 2 details entries just makes the bottom one stomp on the top.

Any input on how to setup logic, in an AWS CloudWatch custom event, to allow multiple sets of events like this?

My current, working but ugly, solution is to have 2 separate CloudWatch events, one per event/isMerged set. e.g.

{
    "source": [
        "aws.codecommit"
    ],
    "detail-type": [
        "CodeCommit Repository State Change"
    ],
    "detail": {
        "event": [
            "pullRequestStatusChanged"
        ],
        "isMerged": [
            "False"
        ]
    }
}

Answer 1

You can target a Lambda function with the original CW Event, then have the Lambda make the decision (check multiple parameters in the JSON strings), then this Lambda can post an SNS message to a Topic which has a subscription to a Lambda etc -- the options are endless.

A sample code for Lambda may be as follows (Python) - Its purpose is different but you will get the idea:

import json
import boto3
from pprint import pprint
from datetime import datetime

def datetime_handler(x, y):
    if isinstance(y, datetime):
        return y.isoformat()
    raise TypeError("Unknown type")

def alarm_handler(event, context):
    pprint("Received the message and start to check alarm state..........")
    json.JSONEncoder.default = datetime_handler
    cw = boto3.client('cloudwatch')
    response = cw.describe_alarms(ChildrenOfAlarmName='cw-alarm')
    length = len(response["MetricAlarms"])
    count = 0
    flag = 0
    messagetobesent = ""
    print("length is " + str(length))
    while (count < length):
        check_msg = response["MetricAlarms"][count]
        print("count is" + str(count))
        currentvalue = check_msg["StateValue"]
        print ("Current Alarm value is " + str(currentvalue))
        if (currentvalue == 'ALARM'):
            messagetobesent = messagetobesent + response["MetricAlarms"][count]["AlarmName"] + " ,"
            flag = flag + 1
        count = count + 1
    #sendingdata = message["StateReason"]
    pprint("Alarm reason is " + messagetobesent)
    pprint("Alarm state is " + messagetobesent)
    if (flag > 0):
        sns = boto3.client('sns')
        responseSNS = sns.publish(TopicArn='arn:aws:sns:aaaaaaaaa:sns', 
                              Message=messagetobesent, 
                              Subject='Notification from cw-alarm')
        pprint("Send SNS notification!")
        return("Alarm!")
    else:
        pprint("No alarm!")
        return("No alarm!")