item_list: [data, database, proddata]
I'm trying to do a conditional when: item.name in item_list
How do I make the when clause explicit so that if my list of items I'm looping thru are [data] only, that 'database' and 'proddata' don't pass the condition as true? I want only EXACT spelling to pass.
Example
---
- name: Explicit example
hosts: localhost
connection: local
vars:
source_list:
- name: proddata
- name: data
- name: other
dest_list1: [this, thing]
dest_list2: [database, proddata]
final_list: '{{ dest_list1 | union(dest_list2) | join(",") }}'
tasks:
- name: test
debug:
msg: '{{ item.name }}'
with_items:
- '{{ source_list }}'
when: item.name in final_list
As you can see, data is not in final_list but it shows up true. I believe because data is contained in proddata and database. I wish to do when: item.name == (item.name in final_list) if possible. I'm just not sure which filter I need.
It would work if your final_list was a list and not a string with comma separated values.
So if your var definition was like this:
final_list: '{{ dest_list1 | union(dest_list2) }}'
the condition
when: item.name in final_list
would be working.
But I assume you have it stored as a string for a reason because you use it somewhere else. If that's the case and you can not change it (you could do the join where you need it as a string) you can simply split it in your condition:
when: item.name in final_list.split(",")
Related
Example playbook -
---
- hosts: localhost
vars:
lesson:
name: Physics
students:
- Bob
- Joe
tasks:
- name: Display student names
debug:
msg: '{{ item }}'
loop: "{{ lesson.students }}"
when: item | default("")
The above playbook works well to output the student names.
However, if the input changes (as per below) such that no student names have been defined, then an error occurs. Is there a simple way to have the playbook skip this task if the list is undefined as per the input below? I realize it would work if the input specifies students: [], but as this input is coming from simple users, they're not going to know this. Much Thanks!
vars:
lesson:
name: Physics
students:
Error: fatal: [localhost]: FAILED! =>
msg: 'Invalid data passed to ''loop'', it requires a list, got this instead: . Hint: If you passed a list/dict of just one element, try adding wantlist=True to your lookup invocation or use q/query instead of lookup.
Update - I've tried the below variations but still get the same error -
---
- hosts: localhost
vars:
lesson:
name: Physics
students:
tasks:
- name: Display student names variation 1
debug:
msg: '{{ item }}'
loop: "{{ lesson.students }}"
when: lesson.students is iterable
- name: Display student names variation 2
debug:
msg: '{{ item }}'
loop: "{{ lesson.students }}"
when: lesson.students is not none
- name: Display student names variation 3
debug:
msg: '{{ item }}'
loop: "{{ lesson.students }}"
when: ( item | default("") ) or ( item is not none )
The real problem is that loop requires a list, even if it is an empty list.
If your var is undefined/None/empty string, it exists but is not a list and your when condition will never get evaluated because loop will fire an error before it is ever reached.
You have to default your var to an empty list in such cases, which will lead to a 0 size loop equivalent to skipping the task.
Since your var is defined but None you need to use the second optional parameter to default so that empty/false values are replaced as well
Note: I used the short alias d to default in my below examples
- name: Display student names
debug:
msg: '{{ item }}'
loop: "{{ lesson.students | d([], true) }}"
A good practice here that would have nipped that error in the bud would be to have a coherent data declaration by either:
not declaring the key at all and use a simple default i.e.
# ... #
vars:
lesson:
name: Physics
# ... #
loop: "{{ lesson.students | d([]) }}"
declare an empty list for the key rather than a None value i.e.
# ... #
vars:
lesson:
name: Physics
students: []
# ... #
loop: "{{ lesson.students }}"
My first proposition is the safest in this case anyway and will work in for all the above vars declarations.
There is a difference between an undefined variable, and variable having None value.
When you set variable name, but leave the right hand side empty. The variable is defined, but it is set to NoneType.
So your when: condition should have additional check for NoneType:
- hosts: localhost
vars:
lesson:
name: Physics
students:
tasks:
- name: Display student names
debug:
msg: '{{ item }}'
loop: "{{ lesson.students }}"
when: ( item | default("") ) or ( item is not none )
This will give:
skipping: [localhost] => (item=None)
I have this vars in the playbook and multiple tasks, I just want to filter the items from vars list based on the prompt input. Right now I have to exclude that item using when from multiple tasks. Please see following example:
vars_prompt:
- name: rmetcd
prompt: "remove etcd: YES OR NO?"
private: no
vars:
containers:
- "etcd"
- "mysql"
- "postgres"
folders:
- "etcd"
- "mysql"
- "postgres"
tasks:
- name: remove container
shell: "docker rm -f {{ item }}"
with_items: "{{ containers }}"
when:
- '"etcd" not in item'
- name: remove folder
file:
path: "{{ item }}"
state: absent
with_items: "{{ folders }}"
when:
- '"etcd" not in item'
when: rmetcd == "NO"
I would take the problem in reverse order: rather than filtering my list for each task to potentially take out an element, I would define my list with default elements and add the additional one if user answered yes.
Note: your two lists are identical, I only kept one in the following example:
---
- hosts: localhost
gather_facts: false
vars_prompt:
- name: rmetcd
prompt: "Remove etcd [yes/no]?"
private: no
vars:
_default_services:
- mysql
- postgres
services: "{{ _default_services + (rmetcd | bool | ternary(['etcd'], [])) }}"
tasks:
- name: task1
debug:
msg: "remove container {{ item }}"
loop: "{{ services }}"
- name: taks2
debug:
msg: "remove folder {{ item }}"
loop: "{{ services }}"
The key points:
I defined a "private" variable _default_services. This is the list of services that will always be included.
I calculated the variable services which is an addition of two lists: _default_services and the additional value to add depending on user input. For this last one:
I used rmetcd containing the value (which should be "yes" or "no")
I applied the bool filter to cast the value to boolean
and I used the ternary filter to select a single element list if true (['etcd']) and an empty list if false ([]).
I'm writing a playbook and want to loop a role over a variable that gets its value from the user. however that value might not always be a list of items, it might be a single value and whenever that happens it throws an error.
My Task:
- name: task name
include role:
name: role name
vars:
cluster_name: '{{ item }}'
loop: "{{ list_or_not }}"
loop_control:
loop_var: item
error:
...Invalid data passed to 'loop', it requires a list...
Have you tried the: "| list" filter?
Sorry cannot test at the moment.
You could test if the variable is a string, and if so, transform it into a single-item list. Something like this:
---
- hosts: localhost
gather_facts: false
tasks:
- set_fact:
list_or_not: ["{{ list_or_not }}"]
when: list_or_not is string
- debug:
msg: "{{ item }}"
loop: "{{ list_or_not }}"
I am trying to use a register in Ansible playbook to store my output. Below is the code which i am using.
I have tried below code
- name: Check if Service Exists
stat: path=/etc/init.d/{{ item }}
register: {{ item }}_service_status
with_items:
- XXX
- YYY
- ZZZ
I need different outputs to be stored in different register variables based on the items as mentioned in the code. It is failing and not able to proceed. Any help would be appreciated.
Updated answer
I think you need to put quotes around it:
register: "{{ item }}_service_status"
Or you can use set_fact (1, 2, 3, 4)
register all the output to a single static variable output and then use a loop to iteratively build a new variable service_status (a list) by looping over each item in the static variable output
- name: Check if Service Exists
stat: path=/etc/init.d/{{ item }}
register: output
with_items:
- XXX
- YYY
- ZZZ
- name: Setting fact using output of loop
set_fact:
service_status:
- rc: "{{ item.rc }}"
stdout: "{{ item.stdout }}"
id: "{{ item.id }}"
with_items:
- "{{ output }}"
- debug:
msg: "ID and stdout: {{ item.id }} - {{ item.stdout }}"
with_items:
- "{{ service_status }}"
Initial Answer
IIUC, this link from the Ansible docs shows how to use register inside a loop (see another example in this SO post).
A couple of points
it may be more convenient to assign the list (XXX, YYY, ZZZ) to a separate variable (eg. 1, 2)
I don't know if this is part of the problem, but with_items is no longer the recommended approach to loop over a variable: instead use loop - see here for an example
vars:
items:
- XXX
- YYY
- ZZZ
- name: Check if Service Exists
stat: path=/etc/init.d/{{ item }}
register: service_status
loop: "{{ items|flatten(levels=1) }}"
- name: Show the return code and stdout
debug:
msg: "Cmd {{ item.cmd }}, return code {{ item.rc }}, stdout {{ item.stdout }}"
when: item.rc != 0
with_items: "{{ service_status.results }}"
I want 'lucy' to follow the user module creators' default behaviour which is to create and use a group matching the user name 'lucy'. However for 'frank' I want the primary group to be an existing one; gid 1003. So my hash looks like this:
lucy:
comment: dog
frank:
comment: cat
group: 1003
And my task looks like this:
- name: Set up local unix user accounts
user:
name: "{{ item.key }}"
comment: "{{ item.value.comment }}"
group: "{{ item.value.group | default(undef) }}"
loop: "{{ users|dict2items }}"
This doesn't work, as undef is not recognised. Nor is anything else I can think of. 'null', 'None' etc. all fail. '' creates an empty string which is not right either. I can't find out how to do it.
Any ideas?
default(omit) is what you are looking for. For example,
- name: Set up local Unix user accounts
user:
name: "{{ item.key }}"
comment: "{{ item.value.comment }}"
group: "{{ item.value.group | default(omit) }}"
loop: "{{ users|dict2items }}"
Comments
Comment by Lucas Basquerotto: "... omit only works correctly when used directly in a module, it won't work in a set_fact ..."
A: You're wrong. For example, default(omit) works both in set_fact and in the module. The first item in the list defaults to false with the result "VARIABLE IS NOT DEFINED!". The second item defaults to omit. Omitted parameter get_checksum defaults to true with the checksum in the results
shell> cat pb.yml
- hosts: localhost
tasks:
- set_fact:
test:
- "{{ gchk|default(false) }}"
- "{{ gchk|default(omit) }}"
- stat:
path: /etc/passwd
get_checksum: "{{ item }}"
loop: "{{ test }}"
register: result
- debug:
var: item.stat.checksum
loop: "{{ result.results }}"
gives
shell> ansible-playbook pb.yml | grep item.stat.checksum
item.stat.checksum: VARIABLE IS NOT DEFINED!
item.stat.checksum: 7c73e9f589ca1f0a1372aa4cd6944feec459c4a8
In addition to this, default(omit) works as expected also in some expressions. For example
- debug:
msg: "{{ {'a': item}|combine({'b': true}) }}"
loop: "{{ test }}"
gives
msg:
a: false
b: true
msg:
b: true
See the results without default values
shell> ansible-playbook pb.yml -e "gchk={{ true|bool }}"