Create SSH key for each user account

[ckunki]

Currently the ITDE writes the SSH key to file /tmp/ITDE/id_rsa with permissions 600, i.e. readable only for the current user. Another user on the same (virtual) machine will find the file existing but cannot read it.

The current ticket therefore requests to select a different file location, enabling the file to exist on a per-user basis. The user's home directory would be suitable in my eyes.

[ckunki]

When using the the home directory of the current user:

• see https://www.studytonight.com/python-howtos/how-to-get-the-home-directory-in-python
• os.path.expanduser('~')

When using the system's temp folder, then

• see detect login name of current user, see https://stackoverflow.com/questions/842059/
• import getpass; getpass.getuser()

[ckunki]

The implementation currently places the file with the private key for SSH in /tmp. On system restart this folder will be emptied.

The Java solution in ETC initially had used file in the build artifacts folder ./target within the working copy of each project. But in January 2023 ETC switched to use the system global temp folder for the following reasons documented in file changes_6.5.1.md. The design document of the ETC unfortunately does not name an explicit design decision.

• make the credentials file survive clean builds with mvn clean
• file is unchanged
• Docker Container, its content, and its hash code remain unchanged
• Docker Container can be reused
• tests can be started faster especially when working with multiple projects.

In summary this sounds to me more like "we wanna keep the file" as like "we wanna ensure the file to vanish at some point in time". Still we can discuss whether we want to prefer subfolders in the global system /tmp or in the home directory of the respective user.

Side note for windows users: Python tempfile.gettempdir() on windows

• may return C:\Users\<user>\AppData\Local\Temp, see ticket #302
• which is per-user 🙂
• and "temporary" (kind of)
• however might not be deleted on system restart, depending on the effective policies.
• E.g. On my machine the file survives a restart.

[ckunki]

@tkilias proposes ~/.cache/exasol/itde/