CODEWITHSUNDEEP
amazon-web-servicesamazon-elbaws-clijmespath
Chris
Chris

Reputation: 390

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

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"
      }
    }
  ]
}

Upvotes: 1

Views: 1164

Answers (3)

Whitney
Whitney

Reputation: 1

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.

Upvotes: 0

junkangli
junkangli

Reputation: 1202

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

Upvotes: 0

Dusan Bajic
Dusan Bajic

Reputation: 10849

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

Upvotes: 3

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