The fundamental problem is that Ansible doesn't allow nested loops -- even
though Ansible looks like a procedural language (it's executing
commands/modules in order and it can loop over things), it really isn't.
The only "simulation" of a for/while loop is the with_foobar stuff, which
calls a lookup plugin that must return a simple list to iterate over. You
could write your own lookup plugin that does a combination of the
subelements and nested plugins, but if you want to stay in the "Ansible
realm", then here's a solution that I used to solve a similar problem:
Define a helper variable that does the work of with_subelements:
monitor_exchange_demand_partners: |
{%- set result = [] -%}
{%- for exchange in monitor_exchanges|default([]) -%}
{%- do result.extend(exchange.demand_partners|default([]) -%}
{%- endfor -%}
{{ result|unique }}
That exploits the fact that Ansible variables are Jinja templates, and that
if a template evaluates into a string representation of a list or dict it
will be converted to that list/dict. You'll have to add this to your
ansible.cfg (Ansible variables in combination with Jinja look like a
functional language, but Jinja lacks all the important tools of functional
programming, so we'll use an extension that turns Jinja into a procedural
language instead):
[defaults]
jinja2_extensions = jinja2.ext.do
Then you can use a simple with_nested:
- datadog_monitor: ...
with_nested:
- monitor_exchange_demand_partners
- monitors
On Thursday, June 18, 2015 at 4:04:51 PM UTC+2, Ashley Penney wrote:
>
> Hi,
>
> We've run into an issue (and a pattern really) using ansible that we've
> been unable to solve and I'm hoping the list can teach us the "ansible way".
>
> The background is that we want to create a number of monitors
> automatically, based on certain information. The solution we have today is
> a variable:
>
> monitor_exchanges:
> - name: exchange1
> demand_partners:
> - 'dp1'
> - 'dp2'
>
> And the consumer:
>
> - name: Create datadog monitors
> datadog_monitor:
> state: "present"
> type: "query alert"
> name: '{{item.0.name}}-{{item.1}} over delivery'
> query:
> "avg({{monitor_interval}}):100*(avg:requests.outbound.transmitted.count{sp_name:{{
> item.0.name}}, dp_name:{{item.1}}} - avg:demand_partner.rps{sp_name:{{
> item.0.name}}, dp_name:{{item.1}}})/avg:demand_partner.rps{sp_name:{{
> item.0.name}}, dp_name:{{item.1}}} > {{monitor_threshold}}"
> message: "test"
> api_key: "{{datadog_api_key}}"
> app_key: "{{datadog_app_key}}"
> with_subelements:
> - monitor_exchanges
> - demand_partners
> when: monitor_exchanges is defined
>
> This then creates, for each exchange a monitor per demand partner. That
> part is fairly easy and works fine but we wanted to externalize the
> 'query'/'name'/'message' part of the above thing, so that we'd have
> something more like:
>
> - name: Create monitors
> datadog_monitor:
> state: "present"
> type: "query alert"
> query: {{item.something.query}}
> name: {{item.something.query}}
> message: {{item.something.query}}
>
> We kept trying to do this with two datastructures, the one from above and
> then
> something like "monitors" that would be a list of hashes containing each
> monitor to create. I couldn't come up with the right combination of
> iteration to make it work however, because I really needed to iterate over
> two separate things in different ways, I couldn't just list the two
> structures, I needed to do something more like:
>
> with_nested:
> - with_subelements:
> - monitor_exchanges
> - demand_partners
> - monitors
>
> Is there another way I can model this that makes sense? I really just
> want to iterate over a list of monitors and then for each monitor iterate
> over the `monitor_exchanges` list to pull all the appropriate data.
>
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