AWS CLI ElasticBeanstalk ec2 Queries

README.md

AWS CLI snippets

The AWS Command Line Interface is a very powerfull ally to anyone managing AWS Infrastructure.

While automating infrastructure with Terraform, some configuration can be quickly retrieved using AWS CLI.

Alternatively, some information is hard to piece together from the AWS console, in which case terminal scripts can provide fast and simple windows into your cloud.

AWS Documentation gives a good starting point and makes a short reference to the very powerfull JMESPath query language.

On top of the excellent examples provided, below are some of the snippets we tend to fall back on a lot.

Most of the below snippets were first constructed using the slightly more verbose, but more versatile Jq and later optimized to use JMESPath (which often provided faster responses)

Get AWS Account information

This one is mainly used for automation of Terraform configuration

aws iam get-user --output text --query='User.Arn' | grep -Eo '[[:digit:]]{12}'

Get ELB by EB Env Name

AWS ElasticBeanstalk uses CloudFormation to provision and tag all resources as well as provides a handy dashboard to manage the overall configuration.

However, some resources are hard to link back to their EB Environment, which the below snippet aims to address.

aws elb describe-load-balancers --query 'LoadBalancerDescriptions[].LoadBalancerName' --output text | xargs -n20 aws elb describe-tags --load-balancer-names --query "TagDescriptions[].[(Tags[?Key=='elasticbeanstalk:environment-name'].Value)[0],LoadBalancerName]" --output text | grep -v None

Notes:

• The elb describe-tags did not provide a --filter option
• xargs is used to pass a list of all ELB names (a required parameter to the elb describe-tags command). A maximum of 20 names can be passed on to this command, which is controlled using the xargs -n option.
• The first Tag which has a Key of environment name is returned

Watch ELB Instances health

The below snippet shows each instance registered with a named ELB and if HealthChecks for these instances are passing. Wrapping this in a watch command will give us a report which is refreshed every second.

export lbname=awseb-e-2-AWSEBL..
watch -n 1 "aws elb describe-instance-health --load-balancer-name $lbname --query 'InstanceStates[].[InstanceId,State]' --output text"

Watch all Instances Tagged for certain EB environment

The elb commands to monitor registered instance health do not provide Ip information, when an instance is failing we may want to trouble shoot the instance by accessing it directly. The below watch should allow us to cross reference the InstanceId from the report above.

export env=honestbee
watch -n2 "aws ec2 describe-instances --filters 'Name=\"tag:elasticbeanstalk:environment-name\",Values=\"$env\"' --query 'Reservations[].Instances[].[InstanceId,InstanceType,State.Name,PublicIpAddress]' --output text | sort -k3"

Report all ELB with their instance count

A more generic report of all load balancers and the instances registered with them (using JMESPath to construct new json structures)

aws elb describe-load-balancers --query "LoadBalancerDescriptions[*].{ID:LoadBalancerName,InstanceId:Instances[*].InstanceId}[*]. {ELB:ID,InstanceId:InstanceId[*]}" --output=json

Filter ELB by InstanceCount

Building on the report above, adding a filter on the number of registered instances to identify ELBs that do not have any Instances registered with them.

This first version uses jq

aws elb describe-load-balancers | jq '.LoadBalancerDescriptions[] | select((.Instances | length) == 0) | .LoadBalancerName'

Show tags for ELBs without instances (without using jq)

aws elb describe-load-balancers --query "LoadBalancerDescriptions[*].{ID:LoadBalancerName,InstanceId:Instances[*].InstanceId,InstanceCount:length(Instances[*])}[?InstanceCount==\`0\`]. [ID]" --output=text | 
while read line
do 
 aws elb describe-tags --load-balancer-name $line --query "TagDescriptions[*].{ID:LoadBalancerName,Tags:Tags[*]}"
done

In this case, instead of using xargs a loop is used to get instance tags.

Get Default VPC Info

Populate 2 Environment variables from a single query

read DEFAULT_VPC_CIDR DEFAULT_VPC_ID <<<$(aws ec2 describe-vpcs --query 'Vpcs[?IsDefault].[CidrBlock,VpcId]' --output text)

Or construct a json object using JMESPath and Jq:

aws ec2 describe-vpcs --query 'Vpcs[?IsDefault].{id:VpcId,cidr:CidrBlock}[0]' | jq '. | {"default-vpc": . }'

which returns:

{
  "default-vpc": {
    "cidr": "172.18.0.0/16",
    "id": "vpc-3d..."
  }
}

Get AWS Region information

Finally, showing more JMESPath functionality to get a comma separated list of Availability zones for a region:

export AWS_REGION=ap-southeast-1
aws ec2 describe-availability-zones --region ${AWS_REGION} --query "AvailabilityZones[*].ZoneName | join(',', @)" --output text