Loading EC2 instance and CFN stack metadata from AWS and into JSON files.

load-aws-metadata.sh

#!/bin/bash

datadir=awsdata
instancedatafile=$datadir/instancedata.json
stackdatafile=$datadir/stack-metadata.json

# Put all the extracted data into one directory.
/bin/mkdir -p $datadir

curl="/usr/bin/curl --retry 3 --silent --show-error --fail"
instance_data_url=http://169.254.169.254/latest

# Use the HTTP reflection interface to determine which instance we are.
instanceid=$($curl $instance_data_url/meta-data/instance-id | /usr/bin/tee $datadir/instanceid)

# Use the AWS CLI to grab the instance data.
/usr/local/bin/aws ec2 describe-instances |
  /usr/bin/jq '.Reservations[].Instances[] | select(.InstanceId == "'$instanceid'")' |
  /usr/bin/tee $instancedatafile > /dev/null

# This is the pattern to extract data from the instance data JSON file.
     zone=$(/usr/bin/jq '.Placement.AvailabilityZone' $instancedatafile)
  stackid=$(/usr/bin/jq '.Tags[] | select(.Key == "aws:cloudformation:stack-id")   | .Value' $instancedatafile)
logicalid=$(/usr/bin/jq '.Tags[] | select(.Key == "aws:cloudformation:logical-id") | .Value' $instancedatafile)

# Need the evals to remove the extra quoting.  This assumes that the
# region is the availability zone with the last character truncated.
zlen=$(eval /bin/echo $zone | /usr/bin/wc -c)
rend=$(expr $zlen - 2)
region=$(eval /bin/echo $zone | /usr/bin/cut -c -$rend)

# Store off the region as it comes in handy and is not in the metadata.
/bin/echo $region > $datadir/region

# Be chatty.
/bin/echo
/bin/echo "Zone: $zone"
/bin/echo "Region: $region"
/bin/echo "Stack: $(eval echo $stackid)"
/bin/echo "Instance: $(eval echo $logicalid)"
/bin/echo

# cfn-get-metadata needs to run priviledged.
sudo /usr/local/bin/cfn-get-metadata -s $(eval echo $stackid) -r $(eval echo $logicalid) --region=$region | /usr/bin/tee $stackdatafile > /dev/null