Installer should offer option for upgrading an existing instance

Problem Definition

Currently the installer always considers that a new installation is being performed. It does not offer an option for upgrading an existing instance, such as Jira and Bitbucket Server installers do.

Suggested Solution

The installer should show two options in its first step:

• one for installing a fresh instance
• the other for upgrading an existing instance

If the option for upgrading an existing instance is chosen, the installer should:

• uninstall the previous instance
• uninstall its Windows / Linux service (if applicable) or update it because the installation directory might change
• in one of the next steps it should ask the user to select the directory used as FISHEYE_INST by the old instance if it cannot be detected automatically from environment variables.

Workaround

There are no known workarounds.