Refactor storage layer to allow for new repository filesystems using drivers. (Reviewed by Cynthia Shang.)
Refactor IO layer to allow for new compression formats, checksum types, and other capabilities using filters. (Reviewed by Cynthia Shang.)
Bug Fixes:
* Fixed missing variable replacements.
* Removed hard-coded host names from configuration file paths.
Documentation Features:
* Allow command-line length to be configured using cmd-line-len param.
* Added compact param to allow CSS to be embedded in HTML file.
* Added pretty param to produce HTML with proper indenting.
* Only generate HTML menu when required and don't require index page.
* Assign numbers to sections by default.
* VM mount points are now optional.
Added an execution cache so that documentation can be generated without setting up the full container environment. This is useful for packaging, keeps the documentation consistent for a release, and speeds up generation when no changes are made in the execution list.
* The repo-path option now always refers to the repository where backups and archive are stored, whether local or remote, so the repo-remote-path option has been removed. The new spool-path option can be used to define a location for queueing WAL segments when archiving asynchronously. Otherwise, a local repository is no longer required.
* Implemented a new config format which should be far simpler to use. See the User Guide and Configuration Reference for details but for a simple configuration all options can now be placed in the stanza section. Options that are shared between stanzas can be placed in the [global] section. More complex configurations can still make use of command sections though this should be a rare use case.
* The default configuration filename is now pgbackrest.conf instead of pg_backrest.conf. This was done for consistency with other naming changes but also to prevent old config files from being loaded accidentally.
* The default repository name was changed from /var/lib/backup to /var/lib/pgbackrest.
* Lock files are now stored in /tmp/pgbackrest by default. These days /run/pgbackrest would be the preferred location but that would require init scripts which are not part of this release. The lock-path option can be used to configure the lock directory.
* Log files are now stored in /var/log/pgbackrest by default and no longer have the date appended so they can be managed with logrotate. The log-path option can be used to configure the lock directory.
* Executable filename changed from pg_backrest to pgbackrest.
