SUMMARY

There is currently no way to use win_get_url and be sure that the expected file is in place without doing extra HTTP requests that waste resources.

If using a checksum and force=true (which to me is a surprising default) the file is always re-downloaded, which if it is pointed to public download sources is inefficient and consumes other peoples resources for no good reason. If force=false a HTTP HEAD request with If-Modified-Since is done, but this is not always enough to ensure that the correct file is downloaded (the local file might have a later modification time than the file on the server).

ISSUE TYPE

• Feature Idea

COMPONENT NAME

win_get_url

ADDITIONAL INFORMATION

There are two ways in which the behaviour of the posix get_url module is better:

1. If the dest file exists and has the correct checksum no HTTP request is done. I cannot see a reason why doing a HTTP request in this case actually makes sense.
2. If dest exists and checksum is different from what is passed in it works as if force=true was passed. Which means you cannot end up in the situation that the module returns ok/no change while the file on disk has a different checksum than what is requested.

If win_get_url was changed to do these two things we could set force=false and be confident that the contents of dest is the file corresponding to the checksum.

$ echo hello > ~/public_html/tmp/hello.txt 
$ echo hei > ~/public_html/tmp/hei.txt 
$ sha1sum ~/public_html/tmp/{hello,hei}.txt 
f572d396fae9206628714fb2ce00f72e94f2258f  /home/kbj/public_html/tmp/hello.txt
b7a7bf03dcafd4d48001d6a2a6fd2ceaefa4cc1e  /home/kbj/public_html/tmp/hei.txt

- hosts: somewhere.example.invalid
  become: no
  tasks:
    - win_get_url:
        url: https://otherplace.example.invalid/~kbj/tmp/hello.txt
        dest: C:/Windows/Temp/greeting.txt
        checksum: f572d396fae9206628714fb2ce00f72e94f2258f
        force: false
    - name: This does not actually make sure greeting.txt has the expected checksum
        win_get_url:
        url: https://otherplace.example.invalid/~kbj/tmp/hei.txt
        dest: C:/Windows/Temp/greeting.txt
        checksum: b7a7bf03dcafd4d48001d6a2a6fd2ceaefa4cc1e
        force: false

This is obviously a contrived example, but replace dest with SomeSoftware.zip and the URLs by download URLs for SomeSoftware-1.2.3.zip and SomeSoftware-1.3.0.zip and you get different behaviour on hosts depending on if they downloaded version 1.2.3 before or after 1.3.0 was released.