ansible

Update a value in a list of dictionaries

I have the following list of dictionaries:

"errorlist": [
    {
        "error": "Not found",
        "path": "/tmp/working/directory1/file1"
    },
    {
        "error": "Not found",
        "path": "/tmp/working/directory2/file1"
    },
    {
        "error": "Not found",
        "path": "/tmp/working/directory1/file2"
    },
    {
        "error": "Not found",
        "path": "/tmp/working/directory2/file2"
    }
]

I'd like to remove the "/tmp/working/" part of the path values, i.e. convert the absolute paths to relative ones.

I've been through similar questions while searching online but haven't found a solution. It should be rather simple but I can't wrap my head around it.

The expected result should be either the original list with updated values or a new list with the same structure.

Solution

  • Filter the basenames and create a list of dictionaries

      paths: "{{ errorlist | map(attribute='path') | map('basename') |
                         map('community.general.dict_kv', 'path') }}"

    gives

      paths:
    - {path: file1}
    - {path: file1}
    - {path: file2}
    - {path: file2}

    zip the lists and combine the items

      result: "{{ errorlist | zip(paths) | map('combine') }}"

    gives

      result:
    - {error: Not found, path: file1}
    - {error: Not found, path: file1}
    - {error: Not found, path: file2}
    - {error: Not found, path: file2}

    Fit the pipes to your needs.

    • Example of a complete playbook for testing
    - hosts: localhost

  vars:

    errorlist:
      - {error: Not found, path: /tmp/working/directory1/file1}
      - {error: Not found, path: /tmp/working/directory2/file1}
      - {error: Not found, path: /tmp/working/directory1/file2}
      - {error: Not found, path: /tmp/working/directory2/file2}

    paths: "{{ errorlist | map(attribute='path') | map('basename') |
                           map('community.general.dict_kv', 'path') }}"
    result: "{{ errorlist | zip(paths) | map('combine') }}"

  tasks:

    - debug:
        var: paths | to_yaml
    - debug:
        var: result | to_yaml
    • Fit the filters to your needs. For example, to remove any part of the string use the filter regex_replace
      paths: "{{ errorlist | map(attribute='path') |
                         map('regex_replace', '/tmp/working/(.*)', '\\1') |
                         map('community.general.dict_kv', 'path') }}"

    gives

      paths:
    - {path: directory1/file1}
    - {path: directory2/file1}
    - {path: directory1/file2}
    - {path: directory2/file2}

    This will result in

      result:
    - {error: Not found, path: directory1/file1}
    - {error: Not found, path: directory2/file1}
    - {error: Not found, path: directory1/file2}
    - {error: Not found, path: directory2/file2}

    Q: "How can I achieve the same result without community.general.dict_kv?"

    A: Use json_query. The below declaration gives the same result

      paths: "{{ errorlist | map(attribute='path') |
                         map('regex_replace', '/tmp/working/(.*)', '\\1') |
                         json_query('[].{path: @}') }}"

    In Ansible 2.9 and lower try to add the filter list

      paths: "{{ errorlist | map(attribute='path') | list |
                         map('regex_replace', '/tmp/working/(.*)', '\\1') | list |
                         json_query('[].{path: @}') | list }}"

    Debugging

    Decompose the pipe

      path1: "{{ errorlist | map(attribute='path') }}"
  path2: "{{ errorlist | map(attribute='path') |
                         map('regex_replace', '/tmp/working/(.*)', '\\1') }}"
  path3: "{{ errorlist | map(attribute='path') |
                         map('regex_replace', '/tmp/working/(.*)', '\\1') |
                         json_query('[].{path: @}') }}"

    and display the types of intermediary results

        - debug:
        msg: "{{ path1 | type_debug }}"
    - debug:
        msg: "{{ path2 | type_debug }}"
    - debug:
        msg: "{{ path3 | type_debug }}"