JQ reshape json

reshape.sh

#!/bin/bash

# Requires gcloud and jq to be installed

# Get instance name and zone, required for our gcloud query
INSTANCE_NAME=$(curl --silent "http://metadata.google.internal/computeMetadata/v1/instance/name" -H "Metadata-Flavor: Google")
ZONE=$(curl --silent "http://metadata.google.internal/computeMetadata/v1/instance/zone" -H "Metadata-Flavor: Google")

# Get a giant blob of json with our instance's metadata
METADATA=$(gcloud compute instances describe $INSTANCE_NAME --zone $ZONE --format json)

# Extract our environment name. There is only ever one of these, per instance.
ENVIRONMENT=$(echo $METADATA | jq -r '.labels.environment')

# Extract our roles. These are "labels" keys with an empty string value.
# Also build and echo our result json object: 
#   1. transform our roles into an array for the "roles" key 
#   2. add in our $ENVIRONMENT value as the "environment" key

# JSON from the .labels field that looks like this (for example)
#
#    "labels": {
#       "elasticsearch": "",
#       "environment": "deploy_test",
#       "postgres": "",
#       "rabbitmq": "",
#       "redis": ""
#     }
#
#   ... will be reshaped into our desired output that looks like this
#
#   {
#     "roles": [
#       "elasticsearch",
#       "postgres",
#       "rabbitmq",
#       "redis"
#     ],
#     "environment": "deploy_test"
#   }
#
# This is the structure our bolt plans expect.

echo $METADATA | jq --arg env $ENVIRONMENT '.labels | with_entries(select(.value == "")) | {roles: [keys[]], environment: $env }'