Question 19031 in Amazon Web Sevices Question posted in
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formatting json tags in ansible between aws commands – Amazon Web Sevices

I need to replace my EBS volumes but need to keep the tags. I have to use aws cli.- I basically have problem to feed the tag information from one aws command output to the other aws command input due to differences of expected format.

I first loop through the volumes with describe-volumes command and collect the tags for each volumes. Something like this

- name: Tags of my EBS volumes
  become: yes
  shell: |
    aws ec2 describe-volumes --volume-ids {{ item.stdout }} --query "Volumes[*].Tags" --output json 
  with_items: "{{ ebsvolumeids.results }}"
  register: ebsvolumetags

This will give a similar formatted output:

    "stdout": "[n    [n        {n            "Key": "cost-center",n            "Value": "22222223222"n        },n        {n            "Key": "LastBackup",n            "Value": "2022.01.01"n        }n    ]n]",

When I want to create a new replacement volume from a snapshot and want to apply the tags the command would like this:

  shell:
    aws ec2 create-volume --snapshot-id <snap-xxxxxxxx> 
    --volume-type gp2 --tag-specifications 
    'ResourceType=volume,Tags={{ item.stdout }}'
  with_items: "{{ ebsvolumetags.results }}"

where I would loop through the output of the previous command. However create-volume command expects a format for Tags like this:

[{Key=LastBackup,Value=2022.01.01},{Key=cost-center,Value=22222223222}]

So for example the correct syntax would be:

aws ec2 create-volume --snapshot-id <snap-xxxxxxxx> --volume-type gp2 --tag-specifications 
'ResourceType=volume,Tags=[{Key=LastBackup,Value=2022.01.01},{Key=cost-center,Value=22222223222}]'

No double quotes. No colons just equal signs. One less deep structure because output had too many [] brackets.

I tried to shape the output of the first command with different ways, for the second to accept but no luck:

  • chain of replace filters
  • using of from_json on the stdout but still didn’t like it
  • have the output as text and replacing n and t

Anybody has an idea how to achieve this?
Thanks

Tags:

2

Answers


  1. 0

    Using shell and the AWS CLI is a poor practice in Ansible, as there are already modules available to execute those operations:

    • the ec2_vol_info will allow you to retrieve the information of the volumes attached to EC2 instances, this will be similar to aws ec2 describe-volumes

    • the ec2_vol will allow you to create and configure volumes, this will be similar to aws ec2 create-volume

    • additionally, there is the ec2_tag module, which allows to add, update or delete tags for the EC2 artifacts.

    Modules have a better error and idem-potency handling, as they already have the logic to verify if the change is needed before applying it, this will allow to execute several times the same playbook if needed.

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  2. 0

    Ansible shell module should only be used as a last resort. That being said, It appears this is a data formatting issue as "Tags" cannot be passed as json to the command "aws ec2 create-volume".

    A workaround would be to convert the tags from json to the correct format (which follows the pattern: [{Key=key1,Value=value1},{Key=key2,Value=value2},{Key=key3,Value=value3},…]) and pass it as a string literal to the aws command. Please refer to the playbook below:

    ---
    - hosts: localhost
      gather_facts: no
      vars:
        tags: ''
      tasks:
      - name: Tags of my EBS volumes
        become: yes
        shell: |
           aws ec2 describe-volumes --volume-ids {{ item.stdout }} --query "Volumes[*].Tags" 
           --output json
        register: ebsvolumetags

      - name: Create tags variable
        set_fact:
          tags: "{{ tags + '{Key=' + item.Key + ',' + 'Value=' + item.Value + '},' }}"
        loop: "{{ ebsvolumetags.stdout | from_json | first }}"

      - name: Create EBS volume with the same tags
        become: yes
        shell: |
             aws ec2 create-volume --snapshot-id <snap-xxxxxxx> --volume-type gp2 
             --tag-specifications 'ResourceType=volume,Tags=[{{ tags[:-1] }}]' 
             --availability-zone <us-east-xx>
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