This is a sample of AWS Lambda function that notifies CodeBuild Notification (only state changes) to Slack via Amazon SNS.

CodeBuiildNotificationToSlack.py

import json
import traceback
from datetime import datetime, timezone, timedelta
from urllib.request import Request, urlopen

SLACK_WEBHOOK_URL = '<your-slack-incomming-webhook-url>'
SLACK_CHANNEL = '<your-slack-channel>'
TEST_EVENT_FILE = './sample__CodeBuild.json'


def lambda_handler(event, context):
    try:
        main(event, context)
    except Exception as e:
        print(traceback.format_exc())


def main(event, context=None):
    event_message = str(event['Records'][0]['Sns']['Message'])
    event_message_json = json.loads(event_message)

    optimezed_info = optimize_notification_info(event_message_json)

    post_to_slack_with_attachment(optimezed_info)


def load_test_event():
    with open(TEST_EVENT_FILE) as f:
        test_event = json.load(f)

    return {
        'Records': [
            {
                'Sns': {
                    'Message': json.dumps(test_event)
                }
            }
        ]
    }


def optimize_notification_info(event):
    ts = int(datetime.fromisoformat(
        event['time'].replace('Z', '')).strftime('%s'))

    color = '#cfd8dc'
    if event['detail']['build-status'] == 'SUCCEEDED':
        color = '#76ff03'
    elif event['detail']['build-status'] == 'STOPPED':
        color = '#ffeb3b'
    elif event['detail']['build-status'] == 'FAILED':
        color = '#d50000'

    attachments = [
        {
            'title': event['detailType'],
            'color': color,
            'ts': ts,
            'fields': [
                {
                    'title': 'project-name',
                    'value': '`{}`'.format(event['detail']['project-name'])
                },
                {
                    'title': 'build-status',
                    'value': '`{}`'.format(event['detail']['build-status'])
                },
                {
                    'title': 'build-id',
                    'value': '`{}`'.format(event['detail']['build-id'])
                }
            ]
        }
    ]

    # not succeeded phases
    if event['detail']['build-status'] != 'IN_PROGRESS':
        not_succeeded_phases_info = get_not_succeeded_phase_info(
            event['detail']['additional-information']['phases'])

        if not_succeeded_phases_info != '':
            attachments[0]['fields'].append(
                {
                    'title': 'NOT-SUCCEEDED-phases',
                    'value': '```\n{}\n```'.format(not_succeeded_phases_info)
                }
            )

    # CloudWatch Logs link
    if 'deep-link' in event['detail']['additional-information']['logs'] and 'group-name' in event['detail']['additional-information']['logs']:
        attachments[0]['fields'].append(
            {
                'title': 'logs',
                'value': '<{deep_link}|{group_name}:{stream_name}>'.format(
                    deep_link=event['detail']['additional-information']['logs']['deep-link'],
                    group_name=event['detail']['additional-information']['logs']['group-name'],
                    stream_name=event['detail']['additional-information']['logs']['stream-name']
                )
            }
        )

    return attachments


def get_not_succeeded_phase_info(phases):
    info = ''

    for phase in phases:
        if 'phase-status' in phase and phase['phase-status'] != 'SUCCEEDED':
            if info != '':
                info += '\n'

            info += '- {type}\n\tstatus: {status}\n\tcontext: "{context}"'.format(
                type=phase['phase-type'],
                status=phase['phase-status'],
                context=', '.join(phase['phase-context'])
            )

    return info


def post_to_slack_with_attachment(attachment):
    post_data = {
        'username': 'CodeBuild Notification',
        'attachments': attachment,
        'channel': SLACK_CHANNEL
    }

    headers = {'Content-Type': 'application/json'}
    data = json.dumps(post_data).encode('utf-8')
    request = Request(SLACK_WEBHOOK_URL, data=data, headers=headers)
    urlopen(request)


if __name__ == '__main__':
    event = load_test_event()
    main(event)

sample__CodeBuildStateEvent.json

{
  "account": "999999999999",
  "detailType": "SampleProject Build State Change",
  "region": "ap-northeast-1",
  "source": "aws.codebuild",
  "time": "2019-11-11T05:05:05Z",
  "notificationRuleArn": "arn:aws:codestar-notifications:ap-northeast-1:999999999999:notificationrule/b5bd8303-f06f-466e-a0a1-XXXXXXXXXXXX",
  "detail": {
      "build-status": "SUCCEEDED",
      "project-name": "SampleProjectBuild",
      "build-id": "arn:aws:codebuild:ap-northeast-1:999999999999:build/SampleProjectBuild:408c5476-c8c0-4aa9-a81b-XXXXXXXXXXXX",
      "additional-information": {
          "cache": {
              "type": "NO_CACHE"
          },
          "timeout-in-minutes": 60,
          "build-complete": true,
          "initiator": "INITIATOR",
          "build-start-time": "Nov 11, 2019 5:03:42 AM",
          "source": {
              "location": "location-link",
              "type": "GITHUB"
          },
          "artifact": {
              "location": ""
          },
          "environment": {
              "image": "aws/codebuild/amazonlinux2-x86_64-standard:1.0",
              "privileged-mode": false,
              "image-pull-credentials-type": "CODEBUILD",
              "compute-type": "BUILD_GENERAL1_SMALL",
              "type": "LINUX_CONTAINER",
              "environment-variables": []
          },
          "logs": {
              "group-name": "/aws/codebuild/SampleProjectBuild",
              "stream-name": "408c5476-c8c0-4aa9-a81b-XXXXXXXXXXXX",
              "deep-link": "https://console.aws.amazon.com/cloudwatch/home?region=ap-northeast-1#logEvent:group=/aws/codebuild/SampleProjectBuild;stream=408c5476-c8c0-4aa9-a81b-XXXXXXXXXXXX"
          },
          "phases": [
              {
                  "phase-context": [],
                  "start-time": "Nov 11, 2019 5:03:42 AM",
                  "end-time": "Nov 11, 2019 5:03:42 AM",
                  "duration-in-seconds": 0,
                  "phase-type": "SUBMITTED",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [],
                  "start-time": "Nov 11, 2019 5:03:42 AM",
                  "end-time": "Nov 11, 2019 5:03:44 AM",
                  "duration-in-seconds": 1,
                  "phase-type": "QUEUED",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:03:44 AM",
                  "end-time": "Nov 11, 2019 5:03:59 AM",
                  "duration-in-seconds": 15,
                  "phase-type": "PROVISIONING",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:03:59 AM",
                  "end-time": "Nov 11, 2019 5:04:02 AM",
                  "duration-in-seconds": 2,
                  "phase-type": "DOWNLOAD_SOURCE",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:04:02 AM",
                  "end-time": "Nov 11, 2019 5:04:35 AM",
                  "duration-in-seconds": 33,
                  "phase-type": "INSTALL",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:04:35 AM",
                  "end-time": "Nov 11, 2019 5:04:35 AM",
                  "duration-in-seconds": 0,
                  "phase-type": "PRE_BUILD",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:04:35 AM",
                  "end-time": "Nov 11, 2019 5:04:53 AM",
                  "duration-in-seconds": 17,
                  "phase-type": "BUILD",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:04:53 AM",
                  "end-time": "Nov 11, 2019 5:05:01 AM",
                  "duration-in-seconds": 8,
                  "phase-type": "POST_BUILD",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:05:01 AM",
                  "end-time": "Nov 11, 2019 5:05:01 AM",
                  "duration-in-seconds": 0,
                  "phase-type": "UPLOAD_ARTIFACTS",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "phase-context": [
                      ": "
                  ],
                  "start-time": "Nov 11, 2019 5:05:01 AM",
                  "end-time": "Nov 11, 2019 5:05:03 AM",
                  "duration-in-seconds": 2,
                  "phase-type": "FINALIZING",
                  "phase-status": "SUCCEEDED"
              },
              {
                  "start-time": "Nov 11, 2019 5:05:03 AM",
                  "phase-type": "COMPLETED"
              }
          ],
          "queued-timeout-in-minutes": 480
      },
      "current-phase": "COMPLETED",
      "current-phase-context": "[: ]",
      "version": "1"
  },
  "resources": [
      "arn:aws:codebuild:ap-northeast-1:999999999999:build/SampleProjectBuild:408c5476-c8c0-4aa9-a81b-XXXXXXXXXXXX"
  ],
  "additionalAttributes": {}
}

slack_notification_cample.png