Can I dynamically set the condition in an IoT Rule SQL? - aws-iot

Question

in this section of yaml file, I need to update condition in sql statement.
for example, user can reset condition to equal 20 instead of 30.
NotifyTemperatureAlarm:
Type: 'AWS::Serverless::Function'
DependsOn: AlertSNSTopic
Properties:
CodeUri: src/notify_temperature_alarm/
Handler: app.lambda_handler
Runtime: python3.9
Architectures:
- x86_64
Events:
PutImageEvent:
Type: IoTRule
Properties:
Sql: Select * FROM 'device/temperature/alarms' where value > 30
Policies:
Version: "2012-10-17"
Statement:
- Effect: Allow
Action: "sns:*"
Resource: "*"
Environment:
Variables:
alert_sns: !Ref AlertSNSTopic

Answer 1

make your condition in parameters section such as
Parameters:
TemperatureThreshold:
Type: Number
Default: '20'
then update NotifyTemperatureAlarm such as
NotifyTemperatureAlarm:
Type: 'AWS::Serverless::Function'
DependsOn: AlertSNSTopic
Properties:
CodeUri: src/notify_temperature_alarm/
Handler: app.lambda_handler
Runtime: python3.9
Architectures:
- x86_64
Events:
PutImageEvent:
Type: IoTRule
Properties:
Sql: !Sub "SELECT * FROM 'device/temperature/alarms' where value > ${TemperatureThreshold}"
Policies:
Version: "2012-10-17"
Statement:
- Effect: Allow
Action: "sns:*"
Resource: "*"
Environment:
Variables:
alert_sns: !Ref AlertSNSTopic
to make TemperatureThreshold Adjustable, you can update it from cloudformation such as
client = boto3.client('cloudformation')
response = client.update_stack(
StackName = "your_stack_name",
UsePreviousTemplate = True,
Capabilities = ['CAPABILITY_IAM'],
Parameters=[
{
'ParameterKey': 'TemperatureThreshold',
'ParameterValue': str(new_threshold),
}
]
)