Question 18279 in Amazon Web Sevices Question posted in
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Find launch template based on tags – Amazon Web Sevices

I’m trying to get the launch template VersionNumber based on the deployment_version tag.

aws ec2 describe-launch-template-versions --launch-template-id lt-1234

Will return something like

{
    "LaunchTemplateVersions": [
        {
            "LaunchTemplateId": "lt-1234",
            "LaunchTemplateName": "api",
            "VersionNumber": 16,
            "LaunchTemplateData": {
                "TagSpecifications": [
                    {
                        "ResourceType": "instance",
                        "Tags": [
                            {
                                "Key": "deployment_version",
                                "Value": "release/6.1"
                            },
                            {
                                "Key": "server_type",
                                "Value": "api"
                            }
                        ]
                    }
                ]
            }
        },
        {
            "LaunchTemplateId": "lt-1234",
            "LaunchTemplateName": "api",
            "VersionNumber": 15,
            "LaunchTemplateData": {
                "TagSpecifications": [
                    {
                        "ResourceType": "instance",
                        "Tags": [
                            {
                                "Key": "deployment_version",
                                "Value": "release/5.7"
                            },
                            {
                                "Key": "server_type",
                                "Value": "api"
                            }
                        ]
                    }
                ]
            }
        }
    ]
}

I tried using jq building something like this

aws ec2 describe-launch-template-versions --launch-template-id lt-1234 | jq '.LaunchTemplateVersions[] | select(.LaunchTemplateData.TagSpecifications.Tags[].Value=="release/6.1")'

But it doesn’t work, with error:

jq: error (at <stdin>:848): Cannot index array with string "Tags"

Most of the jq select examples I could find were made for single level object, does anyone know how to return VersionNumber (16) baes on the tag value (release/6.1) using the example data from above?

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0 
    aws ec2 describe-launch-template-versions --launch-template-id lt-1234 | jq '.LaunchTemplateVersions[] | select(.LaunchTemplateData.TagSpecifications[].Tags[] | select(.Key == "deployment_version" and .Value == "release/6.1")) | .VersionNumber'

  2. 0

    It’s unclear what you want to happen when there are several elements in the TagSpecifications array (I assume there can be different resource types). If you want to get a stream of all version numbers if any tag specification matches, you could use the following, leveraging the fact that the Tags array can be converted to an object:

    .LaunchTemplateVersions[]
| select(any(.LaunchTemplateData.TagSpecifications[].Tags|from_entries; .deployment_version == "release/6.1"))
| .VersionNumber

    to_entries will convert arrays such as [{"Key":"a", "Value":1}, {"Key":"b", "Value":2}] into objects ({"a":1, "b":2} for this example).

    If you are only interested in the first tag, the select becomes:

    select(.LaunchTemplateData.TagSpecifications[0].Tags|from_entries.deployment_version == "release/6.1")

    Since your sample input only contains a single specification, the output is the same for both:

    16

    If you need valid JSON as output, you have to produce an array. To do that, replace the pattern .x[] | select(f) | g with .x | map(select(f) | g). This should output [16].

    But there might be other solutions that are a better fit for you. Maybe you are only interested in tag specifications of type "instance" (and there will be only a single item with that type)?

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