Possibility of Querying EC2 tags from within instance

Question

Amazon lets you  tag EC2 instances with key-value pairs. This enables proper management of large numbers of VMs efficient and easy

Are there ways to query these tags in the same way as some of the other user-set data? For example:

$ wget -q -O - http://169.254.169.254/latest/meta-data/placement/availability-zone
us-east-1d

Answer 1

Try amalgamating AWS new tag API and AWS Metadata tool and i belive you will be able to retrieve tags from current instance

Answer 2

Use the following code in python to query your EC2 instances

from boto import utils, ec2
from os import environ

# import keys from os.env or use default (not secure)
aws_access_key_id = environ.get('AWS_ACCESS_KEY_ID', failobj='XXXXXXXXXXX')
aws_secret_access_key = environ.get('AWS_SECRET_ACCESS_KEY', failobj='XXXXXXXXXXXXXXXXXXXXX')

#load metadata , if  = {} we are on localhost
# http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AESDG-chapter-instancedata.html
instance_metadata = utils.get_instance_metadata(timeout=0.5, num_retries=1)
region = instance_metadata['placement']['availability-zone'][:-1]
instance_id = instance_metadata['instance-id']

conn = ec2.connect_to_region(region, aws_access_key_id=aws_access_key_id, aws_secret_access_key=aws_secret_access_key)
# get tag status for our  instance_id using filters
# http://docs.aws.amazon.com/AWSEC2/latest/CommandLineReference/ApiReference-cmd-DescribeTags.html
tags = conn.get_all_tags(filters={'resource-id': instance_id, 'key': 'status'})
if tags:
    instance_status = tags[0].value
else:
    instance_status = None
    logging.error('no status tag for '+region+' '+instance_id)

Answer 3

Install AWS CLI:

curl "https://s3.amazonaws.com/aws-cli/awscli-bundle.zip" -o "awscli-bundle.zip"
sudo apt-get install unzip
unzip awscli-bundle.zip
sudo ./awscli-bundle/install -i /usr/local/aws -b /usr/local/bin/aws

Get the tags for the current instance:

aws ec2 describe-tags --filters "Name=resource-id,Values=`ec2metadata --instance-id`"

Outputs:

{
    "Tags": [
        {
            "ResourceType": "instance", 
            "ResourceId": "id", 
            "Value": "Webserver", 
            "Key": "Name"
        }
    ]
}

Use a bit of perl to extract the tags:

aws ec2 describe-tags --filters \
"Name=resource-id,Values=`ec2metadata --instance-id`" | \
perl -ne 'print "$1\n" if /\"Value\": \"(.*?)\"/'

Returns:

Webserver

Answer 4

You can download and run a standalone executable to do this

Many a times you cannot install awscli that depends on python and neither docker.

Here is what i found using golang, this persons implementation is easy to understand and worked well for me: https://github.com/hmalphettes/go-ec2-describe-tags

Answer 5

You can use the describe-instances cli call rather than describe-tags:

Here is an example that guides you as how to get the value of 'my-tag-name' for the instance:

aws ec2 describe-instances --instance-id $(curl -s http://169.254.169.254/latest/meta-data/instance-id) --region ap-southeast-1 --query "Reservations[*].Instances[*].Tags[?Key=='my-tag-name'].Value" --output text