Accessing AWS RDS Arn from aws rds describe-db-instances - ansible

Question

I am using Ansible to access some RDS clusters in my account. I have the command working with this.
This is the input data.
"stdout_lines": [
"{",
" \"DBInstances\": [",
" {",
" \"PubliclyAccessible\": false, ",
" \"MasterUsername\": \"xxxxx\", ",
" \"MonitoringInterval\": 0, ",
" \"LicenseModel\": \"general-public-license\", ",
" \"VpcSecurityGroups\": [",
" {",
" \"Status\": \"active\", ",
" \"VpcSecurityGroupId\": \"xxxx\"",
" }",
" ], ",
" \"InstanceCreateTime\": \"xxxxxx\", ",
" \"CopyTagsToSnapshot\": false, ",
" \"OptionGroupMemberships\": [",
" {",
" \"Status\": \"in-sync\", ",
" \"OptionGroupName\": \"xxxxx\"",
........
" \"DBInstanceArn\": \"arn:aws:rds:region:xxxx:db:xxxx\", ",
.......
When running the command below targeting the [0[ item in the array I receive this output.
"{{ (registered.stdout_lines | from_json)['DBInstances'][0]['DBInstanceArn'] }}"
ok: [localhost] => {
"msg": "arn:aws:rds:region :xxxx:db:xxxx"
}
I can get down to the item I need by specifying it like this. I need the array ID in there as there are 3 of them. I have tried to run it this way. But I get all the data.
- name: Show
set_fact:
var: "item.db_instance_arn"
with_items: "{{rds.instances}}"
register: variable
I also get the fact that I want. I just cant output that individual fact.
Is there a way to hit all the items in the array and output the one variable I need?
Thanks in advance. Happy New Year!

Answer 1

You will want (registered.stdout | from_json), not (registered.stdout_lines | from_json) }}, because stdout_lines is a list of str, but from_json wants a str -- I'm surprised your question didn't include the error message that you experienced, because it for sure produces one
Then, once you have straightened out the JSON parsing, you will want to use the map filter, because as you observed, DBInstances is a list, meaning you need to effectively iterate over its objects like so:
- debug:
msg: my DB ARNs are {{
(registered.stdout | from_json).DBInstances
| map(attribute="DBInstanceArn")
| list }}
If you prefer, you can use the json_query filter which uses JMESPath syntax, although most of the time I find it more opaque than helpful:
- debug:
msg: my DB ARNs are {{ (registered.stdout | from_json)
| json_query('DBInstances[*].DBInstanceArn') }}