Filtering the AWS CLI with jq

The JSON-formatted output of the AWS CLI may sometimes feel daunting, especially with a large number of objects. Running 'aws ec2 describe-instances' with more than 10 instances? Bad idea :)

 Fortunately, jq - the self-proclaimed 'sed for JSON data' - is a pretty simple way to filter this output. This will especially come in handy when writing automation scripts :)

Installing jq is one command away:
$ sudo apt-get install jq  (Debian / Ubuntu)
$ yum install jq  (CentOS)
$ brew install jq  (MacOS)

Let's fire up a few EC2 instances and try the following examples.

Show only one field, OwnerId:
$ aws ec2 describe-instances | jq '.Reservations[].OwnerId'

Show all information on the first instance: 
$ aws ec2 describe-instances | jq '.Reservations[].Instance[0]'

Show the instance id and the IP address of the first instance:

$ aws ec2 describe-instances | jq '.Reservations[].Instances[0] | {InstanceId, PublicIpAddress}'

{
  "InstanceId": "i-2181b498",
  "PublicIpAddress": "52.31.231.110"
}

Show the instance id and public IP address of all instances:

$ aws ec2 describe-instances | jq '.Reservations[].Instances[] | {InstanceId, PublicIpAddress}'

{
  "InstanceId": "i-2181b498",
  "PublicIpAddress": "52.31.231.110"
}
{
  "InstanceId": "i-2081b499",
  "PublicIpAddress": "52.31.208.25"
}
{
  "InstanceId": "i-2581b49c",
  "PublicIpAddress": "52.31.207.29"
}
{
  "InstanceId": "i-2781b49e",
  "PublicIpAddress": "52.31.228.234"
}
{
  "InstanceId": "i-2681b49f",
  "PublicIpAddress": "52.31.230.63"
}

 

Fields can also be concatenated, like so:
$ aws ec2 describe-instances | jq '.Reservations[].Instances[] | .InstanceId + " " + .PublicIpAddress'
"i-2181b498 52.31.231.110"
"i-2081b499 52.31.208.25"
"i-2581b49c 52.31.207.29"
"i-2781b49e 52.31.228.234"
"i-2681b49f 52.31.230.63"

Show the instance id and launch time of all instances, sorted by IP address:
$ aws ec2 describe-instances | jq '.Reservations[].Instances[] | .PublicIpAddress + " " + .InstanceId + " " +.LaunchTime' | sort
"52.31.207.29 i-2581b49c 2015-11-16T19:14:57.000Z"
"52.31.208.25 i-2081b499 2015-11-16T19:14:57.000Z"
"52.31.228.234 i-2781b49e 2015-11-16T19:14:57.000Z"
"52.31.230.63 i-2681b49f 2015-11-16T19:14:57.000Z"
"52.31.231.110 i-2181b498 2015-11-16T19:14:57.000Z"

All, let's add an 'environment' tag on all instances, set to either 'dev' or 'prod'.

Now, how about the instance id and IP address of all instances with a 'prod' tag:
$ aws ec2 describe-instances | jq '.Reservations[].Instances[] | select(.Tags[].Value=="prod") | .InstanceId + " " + .PublicIpAddress'
"i-2581b49c 52.31.207.29"
"i-2781b49e 52.31.228.234"
"i-2681b49f 52.31.230.63"

We barely scratched the surface, but I'm sure you get the idea. Make sure you add this nifty tool to your collection!