Rudder

The destination must be the absolute file path, not the destination directory.
If you say /tmp, /tmp is considered to be the destination "file".

While I understand this now, it is very easy to misinterpret, and getting /tmp renamed was not fun. As a suggestion I would change the wording of the this field to something like "Full path of destination file". This would be somewhat symmetrical with the "Path of file to be copied" field. I understand there is some help text when the mouse hovers over the question mark, but if other sys admins are anything like me, when we read "destination" for a file, we think "directory location" not full path, and would not think help is needed. The reason for this is that when copying a file from one place to another, unless you're renaming the file, not many admins would put in the full path for the destination. For example:

cp /etc/hosts /tmp
NOT cp /etc/hosts /tmp/hosts

Also, when a trailing slash was put in (clearly indicating the intent to put the file into a directory), it behaved the same way, namely overwriting (but luckily renaming first) the directory.

May be linked to https://tracker.mender.io/browse/CFE-1811.

When the dir directory exists on the destination:

The issue with checksum is:

 verbose: Checksum comparison replaced by ctime: files not regular

With mtime:

 verbose: File '/tmp/dir' copy_from '/tmp/file'
 verbose: Destination file '/tmp/dir' already exists
 verbose: Image file '/tmp/dir' out of date, should be copy of '/tmp/file'
 verbose: Copy of regular file succeeded '/tmp/file' to '/tmp/dir.cfnew'
 verbose: No depth search when copying '/tmp/dir.cfsaved' so purging does not apply
    info: Cannot move a directory to repository, leaving at '/tmp/dir.cfsaved'
    info: Updated '/tmp/dir' from source '/tmp/file' on 'localhost'

From move_obstruction doc:

If we have promised to make file X a link, but it already exists as a file, or vice-versa, or if a file is blocking the creation of a directory, then normally CFEngine will report an error.

We can:

• If (the destination exists and is a directory) and (the destination does not end with a "/") => Add a "/" at the end of destination.

This allows to fail is the source is a file, and avoid removing the destination.

The only case where a directory got replaced by a file in my tests were when the destination did not end with a "/".

The proposed fix is, when the target is an existing directory on the managed node, to enforce that the destination in the directive ends by a "/". This way, the directory will not be replaced, and an error will be reported.