Schedule lambda function once every day - aws-cloudformation

Question

I have a cloudformation template that works as expected. It install python lambda function.
https://github.com/shantanuo/easyboto/blob/master/install_lambda.txt
But how do I run the function once every day? I know the yaml code will look something like this...
NotifierLambdaScheduledRule:
Type: AWS::Events::Rule
Properties:
Name: 'notifier-scheduled-rule'
Description: 'Triggers notifier lambda once per day'
ScheduleExpression: cron(0 7 ? * * *)
State: ENABLED
In other words, how do I integrate cron setting in my cloudformation template?

Answer 1

An example of CloudFormation template I use:
# Cronjobs
## Create your Lambda
CronjobsFunction:
Type: AWS::Lambda::Function
Properties:
FunctionName: FUNCTION_NAME
Handler: index.handler
Role: !GetAtt LambdaExecutionRole.Arn
Code:
S3Bucket: !Sub ${S3BucketName}
S3Key: !Sub ${LambdasFileName}
Runtime: nodejs8.10
MemorySize: 512
Timeout: 300
## Create schedule
CronjobsScheduledRule:
Type: AWS::Events::Rule
Properties:
Description: Scheduled Rule
ScheduleExpression: cron(0 7 ? * * *)
# ScheduleExpression: rate(1 day)
State: ENABLED
Targets:
- Arn: !GetAtt CronjobsFunction.Arn
Id: TargetFunctionV1
## Grant permission to Events trigger Lambda
PermissionForEventsToInvokeCronjobsFunction:
Type: AWS::Lambda::Permission
Properties:
FunctionName: !Ref CronjobsFunction
Action: lambda:InvokeFunction
Principal: events.amazonaws.com
SourceArn: !GetAtt CronjobsScheduledRule.Arn
## Create Logs to check if events are working
CronjobsFunctionLogsGroup:
Type: AWS::Logs::LogGroup
DependsOn: CronjobsFunction
DeletionPolicy: Delete
Properties:
LogGroupName: !Join ['/', ['/aws/lambda', !Ref CronjobsFunction]]
RetentionInDays: 14
You can check about Rate and Cron Expressions here.
But, if you want to run the above job once a day at 07:00 AM (UTC), then the expression should probably be: cron(0 7 * * ? *)

Answer 2

Others can provide you with a working example with Lambda without Serverless. But if you are using Serverless Transform with AWS Cloudformation (Basically SAM - Serverless Application Model), you can schedule your lambda pretty easily.
For example:
ServerlessTestLambda:
Type: AWS::Serverless::Function
Properties:
CodeUri: src
Handler: test-env-var.handler
Role: !GetAtt BasicLambdaRole.Arn
Environment:
Variables:
Var1: "{{resolve:ssm:/test/ssmparam:3}}"
Var2: "Whatever You want"
Events:
LambdaSchedule:
Type: Schedule
Properties:
Schedule: rate(1 day)
This lambda would trigger itself every day.
More information: https://github.com/awslabs/serverless-application-model/blob/master/versions/2016-10-31.md#schedule