How to ignore a variable if it's not defined

[Sam Sen]

I have a var file with mount points that should be mounted. A common entry for /home goes on all servers. Some servers (e.g. web and perl) have their own set of mount points. I'm using Ansible pull and I build the element dynamically. So for webs, I reach in by using "aws_mounts[nfs_group]", with "nfs_group" equal to "web_mounts" for web servers and "perl_mounts" for perl servers. Generating the variable isn't an issue. However, some servers do not have "nfs_group" defined and the task will fail w/ a "variable is undefined error"

I tried the following:

# tasks

- name: Create fstab entries

  mount:

      fstype: nfs

      state: mounted

      opts: "{{ item.opts }}"

      src: "{{ item.source }}"

      name: "{{ item.dest }}"

  when: item.source is defined

  with_items:

      - "{{ aws_mounts[nfs_group] | default({}) }}"

      - "{{ aws_mounts.common }}"

# vars/main.yml

---

  aws_mounts:

    common:

      - { source: "/home",      dest: "/opt/ansible-home",                          opts: "bind" }

    web_mounts:

      - { source: "/tmp",      dest: "/opt/ansible-web",                          opts: "bind" }

[Kai Stian Olstad]

On 02. nov. 2016 16:24, Sam Sen wrote:
> I have a var file with mount points that should be mounted. A common entry
> for /home goes on all servers. Some servers (e.g. web and perl) have their
> own set of mount points. I'm using Ansible pull and I build the element
> dynamically. So for webs, I reach in by using "aws_mounts[nfs_group]", with
> "nfs_group" equal to "web_mounts" for web servers and "perl_mounts" for
> perl servers. Generating the variable isn't an issue. However, some servers
> do not have "nfs_group" defined and the task will fail w/ a "variable is
> undefined error"
>
> I tried the following:
>
> # tasks
>
> - name: Create fstab entries
> mount:
> fstype: nfs
> state: mounted
> opts: "{{ item.opts }}"
> src: "{{ item.source }}"
> name: "{{ item.dest }}"
> when: item.source is defined
> with_items:
> - "{{ aws_mounts[nfs_group] | default({}) }}"

This run the nfs_group through the default filter and default to empty
list as the second default filter.
So this should work.

- "{{ aws_mounts[nfs_group | default(None)] | default([]) }}"


--
Kai Stian Olstad