Looping through a dictionary to create links

[Aaron Hicks]

Hello the list,

I have  a bunch of machines with some shared file systems. Some of the file systems are not mounted on all the machines. For the filesystems that are mounted, I'd like to check/create a bunch of symbolic links to those filesystems from various places in the filesystem. Some filesystems do not have links (yet) but we may do some other things with them later.

So given a YAML inventory file:

all:

  vars:

    filesystems:

      /sharedfs1:

        - source: /sharedfs1/filesets/home

          target: /home

        - source: /sharedfs1/filesets/foo

          target: /opt/foo

        - source: /sharedfs1/filesets/baa

          target: /opt/baa

        - source: /sharedfs1/filesets/lmod

          target: /opt/lmod

        - source: /scale_wlg_persistent/filesets/baz

          target: /quack/baz

     /sharedfs2:

        - source: /sharedfs2/filesets/scratch

          target: /quack/scratch

      /sharedfs3:

      /sharedfs4:

  children:

    hostlist:

      hosts:

        host1:

        host2:

And the following play, which checks the mount point exists

---

- name: Create links to filesets from shared filesystems

  hosts: all

  tasks:

    - name: Check filesystems are mounted

      stat:

        path: "{{ item.key }}"

      register: fsstat

      loop: "{{ filesystems|dict2items }}"

    - name: Which filesystem mount exists?

      debug:

        var: fsstat.stat.path

      when: item.0.stat.path == item.1.key

      loop: "{{ fsstat.results|product(filesystems|dict2items)|list }}"

Now what I want to do for each filesystem mount that exists, I'd like to create a link from source to target for each list of link hashes associated with each filesystem. Doing this in Python is almost trivial, but a massive pain in Ansible/Jinja2

Regards,

Aaron

[Aaron Hicks]

The Python equivalent I'm trying to make is:

for sharedfs in filesystems:

    if os.path.exists(sharedfs):

        for link in filesystems[sharedfs]:

            os.symlink(link['source']. link['target'])

[Aaron Hicks]

Well, I have a solution but it's very https://www.goodreads.com/quotes/7053458-but-i-am-very-poorly-today-very-stupid

I've had to restructure the inventory:

all:

  vars:

    filesystems:

      - path: /sharedfs1

        links:

          - src: /sharedfs1/filesets/home

            dest: /home

          - src: /sharedfs1/filesets/foo

            dest: /opt/foo

          - src: /sharedfs1/filesets/baa

            dest: /opt/baa

          - src: /sharedfs1/filesets/lmod

            dest: /opt/lmod

          - src: /sharedfs1/filesets/baz

            dest: /quack/baz

      - path: /sharedfs2

        links:

          - src: /sharedfs2/filesets/nobackup

            dest: /quack/nobackup

      - path: /sharefds3

      - path: /sharedfs4

  children:

    hostlist:

      hosts:

        host1:

        host2:

And then the playbook looks like, which does a bit more should/shouldn't testing than initially asked for

---

- name: Create links to filesets from GPFS filesystems

  hosts: all

  vars:

    ansible_become_user: root

    ansible_become_method: sudo

  tasks:

    - name: Check which Spectrum Scale filesystems are mounted

      stat:

        path: "{{ item.path }}"

      register: fsstat

      loop: "{{ filesystems }}"

    # It should be possible to remove this debug and use the filter directly

    - name: Which filesystem mount exists?

      debug:

        msg: "src: {{ item.0.1.src }} dest:{{ item.0.1.dest }}"

      register: linkslist

      when:

        - item.1.stat.exists

        - item.1.stat.path == item.0.0.path

      loop: "{{ filesystems|subelements('links', skip_missing=True)|product(fsstat.results)|list }}"

    - name: Stat filesystem link destinations

      stat:

        path: "{{ item.item.0.1.dest }}"

      become: true

      register: linksstat

      when:

        - item is not skipped

      loop: "{{ linkslist.results }}"

    - name: Remove link destintations (if not a link)

      file:

       path: "{{ item.stat.path }}"

       state: absent

      become: true

      when:

        - item is not skipped

        - item.stat.isdir is defined

        - item.stat.isdir

      loop: "{{ linksstat.results }}"

    - name: Check link destination parent directories

      file:

        path: "{{ item.item.0.1.dest | dirname }}"

        state: directory

      become: true

      when:

        - item is not skipped

        - item.item.0.1.dest | dirname is not match("/")

      loop: "{{ linkslist.results }}"

    - name: Create Scale filesystem links

      file:

        src: "{{ item.item.0.1.src }}"

        dest: "{{ item.item.0.1.dest }}"

        state: link

      become: true

      when:

        - item is not skipped

      loop: "{{ linkslist.results }}"