Best Practices while adding an Amazon monitor in Applications Manager: 

1. Provide proper 'Display name' for the Amazon monitor.
   
2. Select the Amazon services you want to discover from the Amazon services drop box. By default, all the services will be selected. Currently Applications Manager supports EC2, ElasticBeanstalk, DynamoDB, Load Balancers, ECS, EKS, Lambda, SNS, SQS, S3 and RDS. To know more, refer here.
   
3. To monitor an AWS Account, you need an Access Key ID and Secret Access Key. To create the Access Key ID and Secret Access Key, follow these steps.
   
4. Use the keys you obtained from the above step to fill the Access Key ID and Secret Access Key fields when adding an Amazon monitor in Applications Manager.
5. Select the appropriate Account Type for the credentials. By default, the Account Type is AWS Global. To monitor AWS services running in the AWS China/AWS Gov Cloud regions, choose Account Type as AWS China/AWS Gov Cloud and try adding the monitor.
   
6. Based on the Account Type, Global Regions or China Regions or AWS Gov Cloud Regions will be shown. Only from the chosen regions, the resources will be discovered and monitored. By default, 'All regions' will be selected for AWS Global account type.
   
7. Use the Child Discovery option to specify how to discover and monitor the resources (All the discovered monitors under amazon will be considered as child monitors).
   
1. Do not discover: Adds amazon monitor but discovery will not happen.
   
2. Discover and unmanage: Discovers all the child monitors but will set them in the unmanaged state by default.
   
3. Discover and monitor child monitors: Discovers and monitors all the child monitors.
8. Enable Advanced Settings for the below options:
   -> You can also choose to configure an automatic action for a deleted resource using 'Action on Deleted Resource'.
1. Continue Alerting: The option will keep the deleted instances in the AWS console and deleted alerts will be shown in the child and parent monitor in APM. You will receive alerts during every poll.
   
2. Stop Alerting: The option will not affect the health of the deleted instances and will stop alerting.
   
3. Unmanage Resource: The option will unmanage the deleted resources.
   
4. Delete Resource: The option will delete the monitors which have been deleted from the AWS console.
   Note : EC2 instance will be deleted or unmanaged only after it is deleted in the AWS console. As per AWS, EC2 will be deleted from console after 60 mins.
   
9. Regex to filter EC2 Instances name : A regex can be specified in the field to filter and discover the EC2 instances whose name matches the regex.
   
1. Regex may contain alphanumeric characters, hyphen(-), underscore(_) and period(.).
   
2. Specify '.*' to ignore characters. More than one set of '.*' can be used.
   
3. By default, '.*' is specified that allows all the instances.
   
4. At least one '.*' should be present in the regex.
   
5. EC2 instances without names are automatically omitted unless their instance ID match with regex.
   
6. Examples :
   
1. ".*" (allows all instances with any name)
   
2. ".*test" (Allows instances whose name ends with test)
   
3. ".*-.*demo" (Allows instances whose name contains '-' in the middle and ends with demo).
   
10. Stop Discovery : Used to stop further discovery of child resources.
    
1. This option will be useful for editing and updating AWS monitor in APM.
   

While editing and updating existing AWS monitor:

1. If a service is unselected from Amazon Services, all the existing monitors under that service will be deleted from Applications Manager.
   
2. If a region is unselected from Global regions/ China regions, existing monitors in that region will be retained.
3. The option Do not discover in child discovery will be applicable to all the services. Existing monitors won't be affected. If you want to stop discovery for a specific service use Stop discovery option in Advanced Settings. (Point 5 mentioned below)
4. The options Discover and unmanage and Discover and monitor child monitors will be applicable to newly discovered monitors only. Existing monitors will remain in their existing state.
   
5. If you check the Stop Discovery check box, it enables the Services to Stop Discovery drop down. You can choose the services for which you want to stop the further discovery of resources but the existing monitors will continue to be monitored.
6. If you change from Discover and unmanage to Discover and monitor child monitors or vice versa, the existing state of the child monitors will be retained. 
   
7. When you 'Unmanage' and 'Manage' an Amazon monitor, all the child monitors will be unmanaged and managed respectively irrespective of their existing state. This is the behavior of all the parent-child monitors in Applications Manager.

Different hosts and ports that will be accessed while monitoring AWS in Applications Manager

1. Port:
   
1. HTTPS: 443
   
2. Hosts:
   
1. STS - This API is used for authentication (Mandatory)
   
1. sts.{region}.amazonaws.com
   
2. sts.amazonaws.com
   
2. CloudWatch - This API is used for fetching performance metrics (Mandatory)
1. monitoring.{region}.amazonaws.com
   
2. monitoring.amazonaws.com
   
3. EC2
   
1. ec2.{region}.amazonaws.com
   
2. ec2.amazonaws.com
4. EKS
   
1. eks.{region}.amazonaws.com
   
2. FQDN of the EKS cluster - Used to connect to the cluster
   
5. S3
   
1. s3.{region}.amazonaws.com
6. Elastic Load Balancing
   
1. elasticloadbalancing.{region}.amazonaws.com
   
7. RDS
   
1. rds.{region}.amazonaws.com
8. Billing
   
1. ce.us-east-1.amazonaws.com
9. Service wise endpoints - Refer this document for all the supported Service endpoint