{
  "AWSTemplateFormatVersion": "2010-09-09",
  
  "Description" : "[INFRA] Lambda code to start/stop EC2 instances based on tag Schedule. Examples of valid content for Schedule tag are: 08:00-18:00 EC2 instance will run from 08:00 till 18:00 every day. -17:00 wil stop the instance today at 17:00 and rewrite the tag to #-17:00. -17:00T will TERMINATE the instance at 17:00. Any invalid content will be rewritten to start with a #. Any content starting with # will be ignored",
  "Resources" : {
  
    "EC2SchedulerLambda": {
      "Type": "AWS::Lambda::Function",
      "Properties": {
        "Handler": "index.EC2Scheduler",
        "FunctionName" : "EC2Scheduler",
	"Description" : "[INFRA] Lambda code to start/stop EC2 instances based on tag Schedule. NOTE times are UTC. See stack description for further information",
        "Role": { "Fn::GetAtt" : ["EC2SchedulerRole", "Arn"] },
        "Code": {
          "ZipFile":  { "Fn::Join": ["\n", [
		"from datetime import datetime, time",
		"import boto3",
		"import re",
		"",
		"theTag='Schedule'",
		"",
		"doLog = True",
		"",
		"def EC2Scheduler(event, context):",
		"",
		"  now = datetime.now().replace(second=0, microsecond=0)",
		"",
		"  if doLog:",
		"    print 'Reference time is ', now.time()",
		"",
		"  ec2 = boto3.resource('ec2')",
		"",
		"  allInstances = ec2.instances.filter(Filters=[{'Name': 'instance-state-name', 'Values': ['running', 'stopped']}])",
		"",
		"  for instance in allInstances:",
		"    if instance.tags :",
		"      for tag in instance.tags:",
		"        if tag['Key'] == theTag :",
		"          Range=tag['Value']",
		"",
		"          if doLog :",
		"            print instance.instance_id, ",
		"",
		"          shouldrun=shouldRunNow(instance, now, Range)",
		"",
		"          if doLog :",
		"            print 'should %s' %( 'run' if shouldrun else 'NOT run'),",
		"",
		"          alignInstance(instance, shouldrun)",
		"",
		"def shouldRunNow(instance, now, tRange):",
		"",
		"  currentState = instance.state['Code'] == 16",
		"",
		"  # is the tRange commented out",
		"",
		"  if tRange[0:1] == '#':",
		"    if doLog:",
		"      print 'Range starts with # -- no changes',",
		"    return currentState",
		"",
		"  # does the time indicate an end-time only [eg -13:15]",
		"",
		"  if tRange[0:1] == '-':",
		"    tEnd=time(int(tRange[1:3]),int(tRange[4:6]))",
		"",
		"    if doLog:",
		"      print 'End time:', tEnd,",
		"",
		"    if now.time() > tEnd:",
		"",
		"      msg='stop'",
		"      if tRange[6:7] == 'T':",
		"",
		"        terminateAllowed=instance.describe_attribute(Attribute='disableApiTermination')['DisableApiTermination']['Value'] == False",
		"",
		"        if terminateAllowed:",
		"          instance.modify_attribute( Attribute='instanceInitiatedShutdownBehavior', Value='terminate' )",
		"          msg='terminate'",
		"        else:",
		"          msg='stop [terminate not allowed]'",
		"",
		"      # re-tag",
		"",
		"      instance.delete_tags(Tags=[{'Key': theTag, 'Value': tRange}])",
		"      instance.create_tags(Tags=[{'Key': theTag, 'Value': '#'+msg+'@'+tRange}])",
		"",
		"      if doLog:",
		"        print 'time to ', msg, ",
		"",
		"      return False",
		"",
		"    else:",
		"      # leave instance in current state",
		"      if doLog:",
		"        print 'NO time to stop (yet) ',",
		"      return currentState",
		"",
		"  # some simple checks for tRange",
		"",
		"  if not re.match('\\d{2}:\\d{2}-\\d{2}:\\d{2}',tRange):",
		"    if doLog:",
		"      print 'error in format of tag: >', tRange, '< -- no changes required ',",
		"",
		"    instance.delete_tags(Tags=[{'Key': theTag}, {'Value': tRange}])",
		"    instance.create_tags(Tags=[{'Key': theTag, 'Value': '# Err: '+tRange}])",
		"",
		"    return currentState",
		"",
		"  tStart=time(int(tRange[0:2]),int(tRange[3:5]))",
		"  tEnd=time(int(tRange[6:8]),int(tRange[9:11]))",
		"",
		"  inInterval = False",
		"    ",
		"  # first case, start < end --> same day",
		"",
		"  if tStart < tEnd:",
		"    if tStart <= now.time() <= tEnd:        ",
		"      inInterval = True ",
		"",
		"  # second case, end < start --> carry over to next day",
		"",
		"  else:",
		"    if tStart <= now.time() <= time(23,59) or time(0,0) <= now.time() <= tEnd:",
		"      inInterval = True",
		"",
		"  if doLog :",
		"    print 'Ref time is %s interval' %( 'in' if inInterval else 'NOT in'), tRange, ",
		"",
		"  return inInterval",
		"",
		"def alignInstance(inst, requiredOn):",
		"",
		"  actualOn = inst.state['Code'] == 16 ",
		"  msg='is compliant'",
		"",
		"  if actualOn != requiredOn:",
		"    if requiredOn == True:",
		"      msg='starting'",
		"      inst.start()",
		"    else:",
		"      termReq=inst.describe_attribute(Attribute='instanceInitiatedShutdownBehavior')['InstanceInitiatedShutdownBehavior']['Value'] == 'terminate'",
		"",
		"      if termReq:",
		"        msg='terminating'",
		"        inst.terminate()",
		"      else:",
		"        msg='stopping'",
		"        inst.stop()",
		"",
		"  if doLog:",
		"    print '-->', msg",
		""
	  ]]}
        },
        "Runtime": "python2.7"
      }
    },
    
    "EC2SchedulerTick": {
      "Type": "AWS::Events::Rule",
      "Properties": {
	"Description": "ScheduledRule for EC2Scheduler",
	"ScheduleExpression": "rate(10 minutes)",
        "Name" : "EC2SchedulerTick",
	"State": "ENABLED",
	"Targets": [{
	  "Arn": { "Fn::GetAtt": ["EC2SchedulerLambda", "Arn"] },
	  "Id": "TargetFunctionV1"
	}]
      }
    },
    "PermissionForEventsToInvokeLambda": {
      "Type": "AWS::Lambda::Permission",
      "Properties": {
	"FunctionName": { "Ref": "EC2SchedulerLambda" },
	"Action": "lambda:InvokeFunction",
	"Principal": "events.amazonaws.com",
	"SourceArn": { "Fn::GetAtt": ["EC2SchedulerTick", "Arn"] }
      }
    },
    "EC2SchedulerRole": {
      "Type": "AWS::IAM::Role",
      "Properties": {
        "AssumeRolePolicyDocument": {
          "Version": "2012-10-17",
          "Statement": [{ "Effect": "Allow", "Principal": {"Service": ["lambda.amazonaws.com"]}, "Action": ["sts:AssumeRole"] }]
        },
        "Path": "/easytocloud/",
        "RoleName" : "EC2SchedulerRole",
        "Policies": [{
          "PolicyName": "EC2SchedulerPolicy",
          "PolicyDocument": {
            "Version": "2012-10-17",
            "Statement": [
	    {
		"Effect": "Allow",
		"Action": ["logs:*"], 
		"Resource": "arn:aws:logs:*:*:*" 
	    },
	    {	
		"Effect": "Allow",
		"Action": ["ec2:*"], 
		"Resource": "*"
	    }]
          }
        }]
      }
    }
  }
}