Less verbose synchronize module output

SUMMARY

Currently the synchronize module output is very verbose.
On level -vv the same rsync output, including line for each transferred item, is printed 3 times:

I do not know how to call this output; it is the direct rsync output with default terminal color with seemingly no formatting or mangling whatsoever.
The msg var printed in yellow color.
The stdout_lines var printed in yellow color.

ISSUE TYPE

Feature Idea

COMPONENT NAME

synchronize

ADDITIONAL INFORMATION

If several thousand -- or even tens of thousands, by no means an unreasonable possibility -- files are being synchronized it seems excessive, even if I had requested verbosity with -vv.
A couple of different things could be possible:

Make the stdout_lines print only as <omitted>, same as the command module does.
This could be the minimum change if it is possible reasonably.
Don't print the raw output of the rsync command.
The msg return value could be simply the summary from rsync if the stdout_lines contains the full output with each transferred item?
Instead of printing each transferred item in its own line due to rsync option --out-format=[...], could the various different "summary" data that rsync prints give the information that the module needs?
Edit: A major drawback with this is that the user may need the list of files for some further processing as a registered var. Possibly a parameter for the synchronize module such as quiet could be implemented for those cases where the list of transferred items is not interesting. Example of such a summary below.

Number of files: 4,497 (reg: 4,437, dir: 60)
Number of created files: 4,496 (reg: 4,437, dir: 59)
Number of deleted files: 0
Number of regular files transferred: 4,437
Total file size: 37,086,484,092 bytes
Total transferred file size: 37,086,484,092 bytes
Literal data: 37,086,484,092 bytes
Matched data: 0 bytes
File list size: 65,534
File list generation time: 0.074 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 37,095,880,814
Total bytes received: 84,830

sent 37,095,880,814 bytes  received 84,830 bytes  68,003,603.38 bytes/sec
total size is 37,086,484,092  speedup is 1.00

It does not seem useful to print the same information 3 times when the content could be thousands or tens of thousands of lines.
Turning the itemized output off with a suitable rsync_opt switch makes the task not detect whether it was changed. So obviously some output is needed for making the decision whether the task was changed, failed, etc. Possibly the necessary information could be parsed out of rsync summary data block instead of the long itemized output?

Example output from synchronize:

TASK [Copy files] *************************************************************************************************************************************************************
task path: /ansible/testcopy.yml:50
.d..tp..... ./
>f+++++++++ testfile0000
[...]
changed: [host.example.com -> host.example.com] => changed=true
  cmd: /usr/bin/rsync --archive --out-format='<<CHANGED>>%i %n%L' /source/ /destination
  msg: |-
    .d..tp..... ./
    >f+++++++++ testfile0000
[...]
  rc: 0
  stdout_lines:
  - .d..tp..... ./
  - '>f+++++++++ testfile0000'
[...]

Each of the three [...] above is to replace the full list of thousands of files/directories.

The main problem is that you can't override the option

--out-format='<<CHANGED>>%i %n%L'

You can control the output without the option --out-format and with the option --info. For example, given the simple tree below

shell> tree /tmp/ansible/
/tmp/ansible/
├── dest
└── src
    ├── a
    ├── b
    └── c

You can ask for statistics and no files

shell> rsync -a --info=name0,stats2 /tmp/ansible/src/ /tmp/ansible/dest

Number of files: 4 (reg: 3, dir: 1)
Number of created files: 3 (reg: 3)
Number of deleted files: 0
Number of regular files transferred: 3
Total file size: 0 bytes
Total transferred file size: 0 bytes
Literal data: 0 bytes
Matched data: 0 bytes
File list size: 0
File list generation time: 0.001 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 227
Total bytes received: 76

sent 227 bytes  received 76 bytes  606.00 bytes/sec
total size is 0  speedup is 0.00

The below command shows nothing at all

shell> rsync -a --info=name0 /tmp/ansible/src/ /tmp/ansible/dest

Unfortunately, this doesn't work with the module synchronize. You can set rsync_opts

    - synchronize:
        src: /tmp/ansible/src/
        dest: /tmp/ansible/dest
        rsync_opts:
          - --info=name0,stats2
          - --out-format=""
      register: changed_files

, but you can't override --out-format='<>%i %n%L'

  changed_files:
    changed: true
    cmd: /usr/bin/rsync --delay-updates -F --compress --archive --info=name0,stats2 --out-format="" --out-format='<<CHANGED>>%i %n%L' /tmp/ansible/src/ /tmp/ansible/dest
    failed: false
    msg: |-
      .d..t...... ./
      >f+++++++++ a
      >f+++++++++ b
      >f+++++++++ c

      Number of files: 4 (reg: 3, dir: 1)
      Number of created files: 3 (reg: 3)
      Number of deleted files: 0
      Number of regular files transferred: 3
      Total file size: 0 bytes
      Total transferred file size: 0 bytes
      Literal data: 0 bytes
      Matched data: 0 bytes
      File list size: 0
      File list generation time: 0.001 seconds
      File list transfer time: 0.000 seconds
      Total bytes sent: 232
      Total bytes received: 80

      sent 232 bytes  received 80 bytes  624.00 bytes/sec
      total size is 0  speedup is 0.00
    rc: 0
    stdout_lines:
    - .d..t...... ./
    - '>f+++++++++ a'
    - '>f+++++++++ b'
    - '>f+++++++++ c'
    - 'Number of files: 4 (reg: 3, dir: 1)'
    - 'Number of created files: 3 (reg: 3)'
    - 'Number of deleted files: 0'
    - 'Number of regular files transferred: 3'
    - 'Total file size: 0 bytes'
    - 'Total transferred file size: 0 bytes'
    - 'Literal data: 0 bytes'
    - 'Matched data: 0 bytes'
    - 'File list size: 0'
    - 'File list generation time: 0.001 seconds'
    - 'File list transfer time: 0.000 seconds'
    - 'Total bytes sent: 232'
    - 'Total bytes received: 80'
    - sent 232 bytes  received 80 bytes  624.00 bytes/sec
    - total size is 0  speedup is 0.00

This should be considered a bug. Fixing this bug would solve this feature request.

No triage is needed.

ansible-collections / ansible.posix