AWS Systems Manager - RunCommand の定期実行日を判定して、祝日だった場合は翌営業日に延期させてみる（Change Calendar × Lambda）

{
  "schemaVersion": "0.3",
  "description": "AWS-RunPatchBaseline",
  "parameters": {
    "ScheduledDate": {
      "type": "String"
    },
    "InstanceIds": {
      "type": "StringList"
    },
    "Operation": {
      "type": "String",
      "default": "Install"
    }
  },
  "mainSteps": [
    {
      "name": "runPatchBaseline",
      "action": "aws:runCommand",
      "isEnd": true,
      "inputs": {
        "DocumentName": "AWS-RunPatchBaseline",
        "InstanceIds": [
          "{{ InstanceIds }}"
        ],
        "Parameters": {
          "Operation": [
            "{{ Operation }}"
          ]
        }
      }
    }
  ]
}

# lambda_function.py
import os
import json
import hashlib
from datetime import datetime, timedelta, timezone
import boto3
import uuid

ssm = boto3.client('ssm')

CALENDAR_NAMES = [c.strip() for c in os.environ.get('CALENDAR_NAMES', '').split(',') if c.strip()]
TARGET_WEEKDAY = int(os.environ.get('TARGET_WEEKDAY', '1'))  # 0=Mon,1=Tue...
LOOKBACK_DAYS = int(os.environ.get('LOOKBACK_DAYS', '7'))
AUTOMATION_DOCUMENT = os.environ.get('AUTOMATION_DOCUMENT', '<ドキュメント名を記入します>')
AUTOMATION_PARAMETERS_JSON = os.environ.get('AUTOMATION_PARAMETERS_JSON', '{}')
DRY_RUN = os.environ.get('DRY_RUN', 'true').lower() == 'true'
TEST_DATE = os.environ.get('TEST_DATE')  # optional override YYYY-MM-DD

def now_jst():
    return datetime.now(timezone.utc).astimezone(timezone(timedelta(hours=9)))

def iso_at_midnight_jst(date_obj):
    return date_obj.strftime('%Y-%m-%dT00:00:00+09:00')

def is_calendar_open_for_date(date_obj):
    # date_obj is date or datetime
    if isinstance(date_obj, datetime):
        dt = date_obj
    else:
        dt = datetime.combine(date_obj, datetime.min.time())
    at_time = dt.strftime('%Y-%m-%dT00:00:00+09:00')
    resp = ssm.get_calendar_state(CalendarNames=CALENDAR_NAMES, AtTime=at_time)
    state = resp.get('State')
    print(f"GetCalendarState at {at_time} => State={state}")
    return state == 'OPEN'

def client_token_for_date(date_obj):
    if isinstance(date_obj, datetime):
        date_iso = date_obj.date().isoformat()
    else:
        date_iso = date_obj.isoformat()
    token_input = f"{date_iso}|{AUTOMATION_DOCUMENT}"
    return str(uuid.uuid5(uuid.NAMESPACE_DNS, token_input))

def start_automation(scheduled_date_str, parameters):
    token = client_token_for_date(datetime.fromisoformat(scheduled_date_str))
    if DRY_RUN:
        print(f"[DRY_RUN] Would start automation {AUTOMATION_DOCUMENT} for scheduled_date={scheduled_date_str} token={token} params={parameters}")
        return None
    resp = ssm.start_automation_execution(
        DocumentName=AUTOMATION_DOCUMENT,
        Parameters=parameters,
        ClientToken=token
    )
    exec_id = resp.get('AutomationExecutionId')
    print(f"Automation を開始します: {exec_id}")
    return exec_id

def lambda_handler(event, context):
    # TEST_DATE を使うのは DRY_RUN が true のときだけ（誤運用防止）
    if DRY_RUN and TEST_DATE:
        today = datetime.fromisoformat(TEST_DATE).date()
    else:
        today = now_jst().date()

    print(f"Lambda invoked for today (JST): {today.isoformat()}")

    # 今日が実行日かどうかを判定
    if today.weekday() == TARGET_WEEKDAY:
        print("今日はターゲット曜日です")
        if is_calendar_open_for_date(today):
            print("今日は OPEN です -> execute scheduled_date = today")
            try:
                parameters = json.loads(AUTOMATION_PARAMETERS_JSON or "{}")
            except Exception as e:
                print(f"ERROR: Failed to parse AUTOMATION_PARAMETERS_JSON: {e}")
                return
            parameters.setdefault('ScheduledDate', [today.isoformat()])
            start_automation(today.isoformat(), parameters)
            return
        else:
            print("今日は CLOSED です -> skip and leave pending")
            return

    # 実行日ではない場合は過去の日付をチェック
    for d in range(1, LOOKBACK_DAYS + 1):
        sd = today - timedelta(days=d)
        if sd.weekday() != TARGET_WEEKDAY:
            continue
        print(f"スケジュール候補日: {sd.isoformat()}")
        if not is_calendar_open_for_date(sd):
            print(f"scheduled_date {sd.isoformat()} は CLOSED でした")
            if not is_calendar_open_for_date(today):
                print("今日も CLOSED です-> cannot execute now.")
                continue
            try:
                parameters = json.loads(AUTOMATION_PARAMETERS_JSON or "{}")
            except Exception as e:
                print(f"ERROR: Failed to parse AUTOMATION_PARAMETERS_JSON: {e}")
                return
            parameters.setdefault('ScheduledDate', [sd.isoformat()])
            start_automation(sd.isoformat(), parameters)
            return
        else:
            print(f"scheduled_date {sd.isoformat()} was OPEN -> assume handled.")
    print("実行対象の scheduled_date は見つかりませんでした")

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "AllowSSMActionsForLambda",
            "Effect": "Allow",
            "Action": [
                "ssm:GetCalendarState",
                "ssm:StartAutomationExecution",
                "ssm:DescribeAutomationExecutions",
                "ssm:SendCommand",
                "ssm:ListCommands",
                "ssm:ListCommandInvocations",
                "ssm:GetCommandInvocation",
                "ssm:DescribeInstanceInformation"
            ],
            "Resource": "*"
        },
        {
            "Sid": "AllowCloudWatchLogsForLambda",
            "Effect": "Allow",
            "Action": [
                "logs:CreateLogGroup",
                "logs:CreateLogStream",
                "logs:PutLogEvents"
            ],
            "Resource": "arn:aws:logs:*:*:*"
        }
    ]
}

START RequestId: ee89ae0d-71a7-41ec-bd0b-4eabaf2ee935 Version: $LATEST
Lambda invoked for today (JST): 2025-10-08
今日はターゲット曜日です
GetCalendarState at 2025-10-08T00:00:00+09:00 => State=CLOSED
今日は CLOSED です -> skip and leave pending
END RequestId: ee89ae0d-71a7-41ec-bd0b-4eabaf2ee935
REPORT RequestId: ee89ae0d-71a7-41ec-bd0b-4eabaf2ee935	Duration: 471.48 ms	Billed Duration: 984 ms	Memory Size: 128 MB	Max Memory Used: 88 MB	Init Duration: 512.38 ms