Add a new key-value to a json file using Ansible

问题

I'm using Ansible to automate some configuration steps for my application VM, but having difficult to insert a new key-value to an existing json file on the remote host.

Say I have this json file:

{
  "foo": "bar"
}

And I want to insert a new key value pair to make the file become:

{
  "foo": "bar",
  "hello": "world"
}

Since json format is not line based, I'm excluding lineinfile module from my options. Also, I would prefer not to use any external modules. Google keeps giving me examples to show how to read json file, but nothing about change json values and write them back to file. Really appreciate your help please!

回答1:

since the file is of json format, you could import the file to a variable, append the extra key:value pairs you want, and then write back to the filesystem.

here is a way to do it:

---
- hosts: localhost
  connection: local
  gather_facts: false
  vars:

  tasks:
  - name: load var from file
    include_vars:
      file: /tmp/var.json
      name: imported_var

  - debug:
      var: imported_var

  - name: append more key/values
    set_fact:
      imported_var: "{{ imported_var | default([]) | combine({ 'hello': 'world' }) }}"

  - debug:
      var: imported_var

  - name: write var to file
    copy: 
      content: "{{ imported_var | to_nice_json }}" 
      dest: /tmp/final.json

UPDATE:

as OP updated, the code should work towards remote host, in this case we cant use included_vars or lookups. We could use the slurp module.

NEW code for remote hosts:

---
- hosts: greenhat
  # connection: local
  gather_facts: false
  vars:

  tasks:
  - name: load var from file
    slurp:
      src: /tmp/var.json
    register: imported_var

  - debug:
      msg: "{{ imported_var.content|b64decode|from_json }}"

  - name: append more key/values
    set_fact:
      imported_var: "{{ imported_var.content|b64decode|from_json | default([]) | combine({ 'hello': 'world' }) }}"

  - debug:
      var: imported_var

  - name: write var to file
    copy: 
      content: "{{ imported_var | to_nice_json }}" 
      dest: /tmp/final.json

hope it helps

回答2:

ilias-sp's solution is great!

In my case, it lacked the case when we may have to create a base json file. So I had to add this task in the beginning of the play:

- name: Ensure json file exists
copy:
  content: "{}"
  dest: /tmp/var.json
  force: false

回答3:

 - name: update log
    copy:
      content: "{{ log | to_nice_json}}"
      dest: "{{ log_file }}"
    vars:
      log: "{{ (lookup('file', log_file) | from_json) + ([{'job': (build_id if build_id != '' else 'dev'), 'keystore': ks, 'timestamp': ansible_date_time.iso8601}]) }}"
      log_file: log/log.json
      build_id: "{{ lookup('ENV', 'BUILD_ID') }}"
    tags: log

来源：https://stackoverflow.com/questions/50796341/add-a-new-key-value-to-a-json-file-using-ansible

标签

json

ansible