JMES Path / AWS - Retrieve Load Balancer name for given instance ID - amazon-web-services

Question

I need to find the load balancer that a given EC2 instance is attached to using the AWS CLI. I have a working solution that uses jq, however I would like to avoid installing jq as a dependency and write the query in JMESPath if possible. I am stuck on the query format of the JMESPath expression.
I found this question: Filter LoadBalancer By VPC ID, which is exactly what I'm trying to do except filter by instance ID, instead of VPC ID . I think the problem is that the instance ids are in an array.
Working solution with jq:
aws elb describe-load-balancers | jq -r '.LoadBalancerDescriptions[] | select(.Instances[].InstanceId == "i-12345678") | .LoadBalancerName
What I'm trying with JMESPath:
aws elb describe-load-balancers --query "LoadBalancerDescriptions[?Instances[].InstanceId=='i-12345678'] | [].LoadBalancerName"
I feel like I am very close but missing something fundamental.
Example JSON ouput of the describe-load-balancers command from AWS documentation:
{
"LoadBalancerDescriptions": [
{
"Subnets": [
"subnet-15aaab61"
],
"CanonicalHostedZoneNameID": "Z3DZXE0EXAMPLE",
"CanonicalHostedZoneName": "my-load-balancer-1234567890.us-west-2.elb.amazonaws.com",
"ListenerDescriptions": [
{
"Listener": {
"InstancePort": 80,
"LoadBalancerPort": 80,
"Protocol": "HTTP",
"InstanceProtocol": "HTTP"
},
"PolicyNames": []
},
{
"Listener": {
"InstancePort": 443,
"SSLCertificateId": "arn:aws:iam::123456789012:server-certificate/my-server-cert",
"LoadBalancerPort": 443,
"Protocol": "HTTPS",
"InstanceProtocol": "HTTPS"
},
"PolicyNames": [
"ELBSecurityPolicy-2015-03"
]
}
],
"HealthCheck": {
"HealthyThreshold": 2,
"Interval": 30,
"Target": "HTTP:80/png",
"Timeout": 3,
"UnhealthyThreshold": 2
},
"VPCId": "vpc-a01106c2",
"BackendServerDescriptions": [
{
"InstancePort": 80,
"PolicyNames": [
"my-ProxyProtocol-policy"
]
}
],
"Instances": [
{
"InstanceId": "i-207d9717"
},
{
"InstanceId": "i-afefb49b"
}
],
"DNSName": "my-load-balancer-1234567890.us-west-2.elb.amazonaws.com",
"SecurityGroups": [
"sg-a61988c3"
],
"Policies": {
"LBCookieStickinessPolicies": [
{
"PolicyName": "my-duration-cookie-policy",
"CookieExpirationPeriod": 60
}
],
"AppCookieStickinessPolicies": [],
"OtherPolicies": [
"my-PublicKey-policy",
"my-authentication-policy",
"my-SSLNegotiation-policy",
"my-ProxyProtocol-policy",
"ELBSecurityPolicy-2015-03"
]
},
"LoadBalancerName": "my-load-balancer",
"CreatedTime": "2015-03-19T03:24:02.650Z",
"AvailabilityZones": [
"us-west-2a"
],
"Scheme": "internet-facing",
"SourceSecurityGroup": {
"OwnerAlias": "123456789012",
"GroupName": "my-elb-sg"
}
}
]
}

Answer 1

aws elb describe-load-balancers --query LoadBalancerDescriptions[?Instances[0].InstanceId==`i-55555555`].LoadBalancerName

Answer 2

Since Instances is an array, you should make use of the contains function to search for your instance id.
aws elb describe-load-balancers --query LoadBalancerDescriptions[?contains(Instances[*].InstanceId,`i-12345678`)].LoadBalancerName

Answer 3

Use LoadBalancerDescriptions[?Instances[*].InstanceId==`i-55555555`] to iterate through the instances.
LoadBalancerDescriptions[?Instances[0].InstanceId==`i-55555555`] will only use the first element in the array.