How do I get RDS instance id for an Elastic Beanstalk environment?

Question

I'd like to write a script that snapshots and restores the RDS database associated with my Elastic Beanstalk environment. How can I get the RDS instance id which I'll be plugging into the aws rds create-db-snapshot and aws rds restore-db-instance-from-db-snapshot commands?

I know that it can be seen in the Configuration tab in the web interface, but I wanted to get it using a command executed in the shell.

Answer 1

While you can configure an RDS instance when you configure an Elastic Beanstalk application, they are not really tied together. They can both run in a VPC but that's the only real grouping per se. You could easily use the RDS for something else too.

You will likely want to use something like aws rds describe-db-instances to get the RDS instance information coupled with an instance name (i.e. application1-ebs-rds) to allow you to locate the RDS.

Answer 2

The most straightforward way that I've found involves the following steps

1. SSH into your instance with $ eb ssh {environment-id}

2. Run the following command from the SSH terminal to get the RDS instance id:

   $ sudo /opt/elasticbeanstalk/bin/get-config environment --output YAML | grep RDS_HOSTNAME | sed -n "s/^RDS_HOSTNAME: \([a-z0-9]*\).*$/\1/p"

The above command gets all the available environment variables, including the special ones that start with RDS_, greps for the RDS_HOSTNAME variable, and then extracts the value you need with sed.

Answer 3

You can get a history of event this way...

aws elasticbeanstalk describe-events --environment-name your_environment_name

One of the events in your history should include the db-instance-identifier...

{
    "ApplicationName": "some-app", 
    "EnvironmentName": "some-env", 
    "Severity": "INFO", 
    "RequestId": "some-ref-id", 
    "Message": "Created RDS database named: some-db-instance-identifier", 
    "EventDate": "2017-01-30T23:23:37.734Z"
}, 

Then you can take that message string and get the DB Instance Identifier to use here...

aws rds create-db-snapshot --db-instance-identifier some-db-instance-identifier --db-snapshot-identifier name-of-snapshot

It's a bit of work. :)