how to filter an item list - with_items filter using RegEx ?

[Torsten Reinhard]

Hi all,

like probably most of you, we have multiple servers with multiple application instances (Tomcat, Apache, ..) on it, for example structured like this:

[cae:children]
cae-1
cae-2

[cae-1]
pbdelsweb001.mydomain.com
[cae-2]
pbdelsweb002.mydomain.com

For each group we have a *.yml file at group_vars directoy in the inventory:

cae-1.yml:
---
cae_instance:
-
    index: _1_a
    port: 8700
-
    index: _1_b
    port: 9700
-
    index: _1_c
    port: 10700
-
    index: _1_k
    port: 12700

All these instances are setup by a simple playbook:

- hosts: cae
  user: myuser

  vars_files:
    - vars/stage-{{stage}}.yml  

  roles:
    - { role: cae-tomcat, params: "{{ cae_instance }}" }

This is all fine - but now I have to fullfill the requirement to be able to address only the "_k" instances - or only the "_a" instances - that meens one or more instances out of the complete list.

Is there an option to "filter" the list of instances ? Something like

  with_items
   - filter: (".*_k" )

Do I have to write my own Iterator(s) for this ?

Thanx for any hints, Torsten

[Michael DeHaan]

If you are attempting to talk to only certain instances, usage of the host group specifier "hosts:" is the way to do it.

To talk to all instances ending in that pattern

- hosts: *_k

The docs also show how to combine patterns and negate them.

(The group_by module can also be used to create groups of arbitrary criteria based on facts, but is not needed here)

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[Torsten Reinhard]

Hi,

it´s not about "hosts" filtering - in my case it´s always "hosts: cae".

I have some files in

group_vars/cae-1.yml
group_vars/cae-2.yml
..
group_vars/cae-xx.yml

according to the group(s) defined in my /inventory/hosts file.

Inside these group_vars there´s a list of instances, running on that machine:

---
cae_instance:
-
    index: _1_a
    port: 8700

...

-
    index: _1_k
    port: 12700

The question is now: how to filter that list ?

I know I can iterate the list using the "with_items" expression - but I want to "skip" or "filter" some items, lets say by using RegEx on one (or more) attributes of the list items.

Any solution for that ?

Regards, Torsten

[Ted Eiles]

We are attempting to filter a set of AWS subnets for creating an ASG.

In a VPC, we have some subnets tagged as "Network=private".  When creating an ASG for worker instances, we need to set the ASG's AZs and subnets to the AZs and subnets of all private subnets in the VPC.  So, being able to with_items over the subnets and filtering on tags "Network=private" is useful.

For AWS work, filtering AWS entities (hosts, IAM roles, subnets, VPC', etc...) on one or more tags seems like it would be common.

--- Ted

[Michael DeHaan]

Sounds like you may wish to write a filter plugin.

If so, see if you need more information, if needed, we can provide some pointers.

To view this discussion on the web visit https://groups.google.com/d/msgid/ansible-project/2838d5ad-7fb3-43b3-be51-18fd262832f8%40googlegroups.com.