Ansible - Looking for files and compare their hash - ansible

Question

Practice:
I have the file files.yml with a list of files and their respective md5_sum hash, like:
files:
- name: /opt/file_compare1.tar
hash: 9cd599a3523898e6a12e13ec787da50a /opt/file_compare1.tar
- name: /opt/file_compare2tar.gz
hash: d41d8cd98f00b204e9800998ecf8427e /opt/file_compare2.tar.gz
I need to create a playbook to check this list of files if the current hash is the same or if it was changed, the playbook should have a debug message like below:
---
- hosts: localhost
connection: local
vars_files:
- files.yml
tasks:
- name: Use md5 to calculate checksum
stat:
path: "{{ item.name }}"
checksum_algorithm: md5
register: hash_check
with_items:
- "{{ files }}"
- name: Debug files - Different
debug:
msg: |
"Hash changed: {{ item.name }}"
when:
- item.hash != hash_check
with_items:
- "{{ files }}"
- name: Debug files - Equal
debug:
msg: |
"Hash NOT changed: {{ item.name }}"
when:
- item.hash == hash_check
with_items:
- "{{ files }}"
- debug:
msg: |
- "{{ hash_check }} {{ item.name }}"
with_items:
- "{{ files }}"

Answer 1

For example, given the files
files:
- name: /scratch/file_compare1.tar
hash: 4f8805b4b64dcc575547ec1c63793aec /scratch/file_compare1.tar
- name: /scratch/file_compare2.tar.gz
hash: 2dc4f1e9ca4081cc49d25195627982ef /scratch/file_compare2.tar.gz
the tasks below
- name: Use md5 to calculate checksum
stat:
path: "{{ item.name }}"
checksum_algorithm: md5
register: hash_check
loop: "{{ files }}"
- name: Debug files - Different
debug:
msg: |
Hash NOT changed: {{ item.0.name }}
{{ item.0.hash.split()|first }}
{{ item.1 }}
with_together:
- "{{ files }}"
- "{{ hash_check.results|map(attribute='stat.checksum')|list }}"
when: item.0.hash.split()|first == item.1
give
msg: |-
Hash NOT changed: /scratch/file_compare1.tar
4f8805b4b64dcc575547ec1c63793aec
4f8805b4b64dcc575547ec1c63793aec
msg: |-
Hash NOT changed: /scratch/file_compare2.tar.gz
2dc4f1e9ca4081cc49d25195627982ef
2dc4f1e9ca4081cc49d25195627982ef
A more robust option would be to create a dictionary with the calculated hashes
- name: Use md5 to calculate checksum
stat:
path: "{{ item.name }}"
checksum_algorithm: md5
register: hash_check
loop: "{{ files }}"
- set_fact:
path_hash: "{{ dict(_path|zip(_hash)) }}"
vars:
_path: "{{ hash_check.results|map(attribute='stat.path')|list }}"
_hash: "{{ hash_check.results|map(attribute='stat.checksum')|list }}"
gives
path_hash:
/scratch/file_compare1.tar: 4f8805b4b64dcc575547ec1c63793aec
/scratch/file_compare2.tar.gz: 2dc4f1e9ca4081cc49d25195627982ef
Then use this dictionary to compare the hashes. For example, the task below gives the same results
- name: Debug files - Different
debug:
msg: |
Hash NOT changed: {{ item.name }}
{{ item.hash.split()|first }}
{{ path_hash[item.name] }}
loop: "{{ files }}"
when: item.hash.split()|first == path_hash[item.name]
The next option is to create a dictionary with the original hashes and both lists of original and calculated hashes
- name: Use md5 to calculate checksum
stat:
path: "{{ item.name }}"
checksum_algorithm: md5
register: hash_check
loop: "{{ files }}"
- set_fact:
hash_name: "{{ dict(_hash|zip(_name)) }}"
hash_orig: "{{ _hash }}"
hash_stat: "{{ hash_check.results|map(attribute='stat.checksum')|list }}"
vars:
_hash: "{{ files|map(attribute='hash')|map('split')|map('first')|list }}"
_name: "{{ files|map(attribute='name')|list }}"
gives
hash_name:
2dc4f1e9ca4081cc49d25195627982ef: /scratch/file_compare2.tar.gz
4f8805b4b64dcc575547ec1c63793aec: /scratch/file_compare1.tar
hash_orig:
- 4f8805b4b64dcc575547ec1c63793aec
- 2dc4f1e9ca4081cc49d25195627982ef
hash_stat:
- 4f8805b4b64dcc575547ec1c63793aec
- 2dc4f1e9ca4081cc49d25195627982ef
Then calculate the difference of the lists and use it to extract both lists of changed and unchanged files
- set_fact:
files_diff: "{{ _diff|map('extract', hash_name)|list }}"
files_orig: "{{ _orig|map('extract', hash_name)|list }}"
vars:
_diff: "{{ hash_orig|difference(hash_stat) }}"
_orig: "{{ hash_orig|difference(_diff) }}"
- name: Debug files changed
debug:
var: files_diff
- name: Debug files NOT changed
debug:
var: files_orig
gives
files_diff: []
files_orig:
- /scratch/file_compare1.tar
- /scratch/file_compare2.tar.gz

Answer 2

I used your suggestion to complement the playbook, it's working now.
The idea is to get a list of files, read each one and compare with both hash, file, and current hash.
---
- hosts: localhost
connection: local
gather_facts: false
vars_files:
- files3.yml
tasks:
- stat:
path: "{{ item.file }}"
checksum_algorithm: md5
loop: "{{ files }}"
register: stat_results
- name: NOT changed files
debug:
msg: "NOT changed: {{ item.stat.path }}"
when: item.stat.checksum == item.item.checksum.split()|first
loop: "{{ stat_results.results }}"
loop_control:
label: "{{ item.stat.path }}"
- name: Changed files
debug:
msg: "CHANGED: {{ item.stat.path }}"
when: item.stat.checksum != item.item.checksum.split()|first
loop: "{{ stat_results.results }}"
loop_control:
label: "{{ item.stat.path }}"
Result:
>> ansible-playbook playbooks/check-file3.yml
PLAY [localhost] ********************************************************************************************************************************************************************************************************************
TASK [stat] *************************************************************************************************************************************************************************************************************************
ok: [localhost] => (item={'file': '/opt/file_compare1.tar', 'checksum': '9cd599a3523898e6a12e13ec787da50a /opt/file_compare1.tar'})
ok: [localhost] => (item={'file': '/opt/file_compare2.tar.gz', 'checksum': 'd41d8cd98f00b204e9800998ecf8427e /opt/file_compare2.tar.gz'})
TASK [NOT changed files] ************************************************************************************************************************************************************************************************************
skipping: [localhost] => (item=/opt/file_compare1.tar)
ok: [localhost] => (item=/opt/file_compare2.tar.gz) => {
"msg": "NOT changed: /opt/file_compare2.tar.gz"
}
TASK [Changed files] ****************************************************************************************************************************************************************************************************************
ok: [localhost] => (item=/opt/file_compare1.tar) => {
"msg": "CHANGED: /opt/file_compare1.tar"
}
skipping: [localhost] => (item=/opt/file_compare2.tar.gz)
PLAY RECAP **************************************************************************************************************************************************************************************************************************
localhost : ok=3 changed=0 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0