Comparing files using Ansible

Question

I need to find a way where I can compare elasticsearch template folders in given elasticsearch Data host group. Meaning if the directory is /usr/local/elasticsearch/config/templates/, I need to make sure all the files inside that directory in that ansible host group is same.

No extra template files or difference version template files. I haven't been able to figure out how to do this.

Answer 1

Try combining ansible with rsync dry-run using the shell module:

ansible -i production data_hosts -l '!~host1' -f 1 -m shell \
  -a 'rsync --checksum --delete --dry-run -r -v host1.example.com:/usr/local/elasticsearch/config/templates/ /usr/local/elasticsearch/config/templates'

Explanation

• Compares the /usr/local/elasticsearch/config/templates directory on all hosts in the [data_hosts] group to host1
• Excludes host1.example.com using the -l limit argument: -l '!~host1'
• Uses -f 1 to only run one compare at a time. Optional, but helped in my case because the directories contained large numbers of files (>10K)
• Uses --dry-run to prevent rsync from actually sync'ing the directories
• Uses --delete to list extraneous files in the destination directory
• Uses --checksum to compare files based on checksum rather than mod-time and size

Notes

• You could modify this one-liner to perform the sync by removing --dry-run. Consider adding -z to compress file data during transfer, and -a for archive mode.

• The production inventory file would look like this:

  [data_hosts]
  host1.example.com
  host2.example.com
  host3.example.com
  host4.example.com