read_csv not happening line by line - ansible

Question

I am trying to read a csv file. However, during print its not reading line by line instead its going over some internal loop and duplicating results.
- name: read csv
read_csv:
path: /u00/app/monitor/newrelic_test.csv
key: Application
register: newrelic
- name: Print newrelic var
ansible.builtin.debug:
var: newrelic.list
output looks lke below:
[testserver1] =>
"newrelic.list":
"Application": "Microsoft",
"env": "Test",
"Datacenter": "DC1",
"Hostname": "testserver1",
},
"Application": "Apple",
"env": "Test",
"Datacenter": "DC2",
"Hostname": "testserver2",
}
[testserver2] => {
"newrelic.list":
{
"Application": "Microsoft",
"env": "Test",
"Datacenter": "DC1",
"Hostname": "testserver1",
},
"Application": "Apple",
"env": "Test",
"Datacenter": "DC2",
"Hostname": "testserver2",
}
]
csv file:
Application,env,Datacenter,Hostname
Microsoft,Test,DC1,testserver1
Apple,Test,DC2,testserver2
Expected result shall be:
[testserver1] =>
"newrelic.list":
"Application": "Microsoft",
"env": "Test",
"Datacenter": "DC1",
"Hostname": "testserver1",
}
[testserver2] => {
"newrelic.list":
{
"Application": "Apple",
"env": "Test",
"Datacenter": "DC2",
"Hostname": "testserver2",
}
]
Edit : - Next block
- name: copy template
template:
src: /u00/ansible/Playbooks/files/infra-config.yml_template
dest: /u00/app/monitor/infra-config.yml
loop: "{{ newrelic.list }}"
loop_control:
loop_var: item
Issue: if newrelic.list is not been used then get error as below:
[testserver1]: FAILED! => {"msg": "Invalid data passed to 'loop', it requires a list, got this instead: {'dict':
I tried adding dict2items but then template not able to read items.

Answer 1

The read_csv module doesn't read a CSV file "line by line"; from the documentation:
Read[s] a CSV file and return[s] a list or a dictionary, containing one dictionary per row.
So when you run this task:
- name: read csv
read_csv:
path: data.csv
key: Application
register: newrelic
You get a variable newrelic which has an empty list element and a dict element containing the data from the CSV file, keyed by Application (because that's what you asked for). If use a debug task to look at the value of newrelic, we see:
ok: [localhost] => {
"newrelic": {
"changed": false,
"dict": {
"Apple": {
"Application": "Apple",
"Datacenter": "DC2",
"Hostname": "testserver2",
"env": "Test"
},
"Microsoft": {
"Application": "Microsoft",
"Datacenter": "DC1",
"Hostname": "testserver1",
"env": "Test"
}
},
"failed": false,
"list": []
}
}
It's not clear exactly what you're trying to do here, but if you want to look up values from your CSV file by inventory hostname, you would need to key it by Hostname instead:
- name: read csv
read_csv:
path: data.csv
key: Hostname
register: newrelic
And then you could write:
- name: Print newrelic var
ansible.builtin.debug:
var: newrelic.dict[inventory_hostname]
Assuming you have hosts testserver1 and testserver2 in your inventory, a playbook like this:
- hosts: localhost
gather_facts: false
tasks:
- name: read csv
read_csv:
path: data.csv
key: Hostname
register: newrelic
- hosts: all
gather_facts: false
tasks:
- name: Print newrelic var
ansible.builtin.debug:
var: hostvars.localhost.newrelic.dict[inventory_hostname]
Would result in this output:
PLAY [localhost] ***************************************************************
TASK [read csv] ****************************************************************
ok: [localhost]
PLAY [all] *********************************************************************
TASK [Print newrelic var] ******************************************************
ok: [testserver1] => {
"hostvars.localhost.newrelic.dict[inventory_hostname]": {
"Application": "Microsoft",
"Datacenter": "DC1",
"Hostname": "testserver1",
"env": "Test"
}
}
ok: [testserver2] => {
"hostvars.localhost.newrelic.dict[inventory_hostname]": {
"Application": "Apple",
"Datacenter": "DC2",
"Hostname": "testserver2",
"env": "Test"
}
}
PLAY RECAP *********************************************************************
localhost : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
testserver1 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
testserver2 : ok=1 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0