nbdkit-release-notes-1.18 - release notes for nbdkit 1.18
These are the release notes for nbdkit stable release 1.18. This describes the major changes since 1.16.
nbdkit 1.18.0 was released on 27th February 2020.
There were no security issues found. All past security issues and information about how to report new ones can be found in nbdkit-security(1).
New nbdkit-eval-plugin(1) lets you write a plugin entirely on a single command line. It is similar to nbdkit-sh-plugin(3).
nbdkit-ext2-plugin is deprecated and will be removed in the next release after this one (nbdkit 1.20). As a replacement use nbdkit-ext2-filter(1) like this:
nbdkit --filter=ext2 file fs.img ext2file=/disks/disk.raw
nbdkit-python-plugin(3) now offers a version 2 API which avoids copying the data buffer, improving performance. The original protocol (now retrospectively called version 1) is still supported for backwards compatibility. The version 1 protocol was also enhanced to support the buffer protocol for the pread method, and memoryview for pwrite, improving performance by reducing copies (Nir Soffer).
The Python plugin now prints readable stack traces when an exception is thrown (Nir Soffer).
New methods implemented in the Python plugin: cache, can_cache, can_zero, can_fast_zero, can_multi_conn, can_fua.
In nbdkit-curl-plugin(1), new options
capath (Wiktor Gołgowski).
nbdkit-split-plugin(1) now supports extents (Eric Blake).
file= is now a magic config key, meaning it can be omitted in most circumstances (Eric Blake).
The VDDK plugin now no longer needs
$LD_LIBRARY_PATH to be set. The correct library load path is automatically inferred from the
libdir parameter (Eric Blake).
Verbose messages about calls to VDDK functions Read and Write can now be suppressed by setting -D vddk.datapath=0.
New nbdkit-ext2-filter(1), which replaces the deprecated nbdkit-ext2-plugin. This filter allows you to read and write files inside ext2, ext3 or ext4 filesystems. The new filter has the same features as the plugin, and one enhancement: optionally the name of the file to serve can be picked from the client-supplied exportname. The old plugin will be removed in nbdkit 1.20 (Eric Blake).
New nbdkit-extentlist-filter(1) lets you specify a static list of extents from a file which can be placed on top of plugins which don't export extent information.
New nbdkit-ip-filter(1) lets you allow and deny incoming connections by client IP address, similar to TCP wrappers or a firewall.
New nbdkit-nofilter-filter(1) is a null filter, used for testing.
The stats filter now collects time elapsed per operation, per operation and total rates, and adds stats for the flush method. The output is shown in human sizes making it easier to understand. (Nir Soffer).
New --swap option which allows nbdkit to be safely used to serve swap space to the same machine.
Debug flags (-D) can now be applied to the server core (using -D nbdkit.*). Underscores in debug flags can now be replaced by dots, allowing a kind of namespacing. Debug flags which are not consumed now no longer give an error, so you can use them without needing to detect if the plugin supports them. New server debug flags -D nbdkit.backend.controlpath=0 and -D nbdkit.backend.datapath=0 were added to suppress some very verbose messages when verbose mode is enabled.
There is a new
.get_ready method which is called after
.config_complete and before the server forks or changes directory. It is the last chance to do any global preparation that is needed to serve connections. Plugins have previously done this work in
.config_complete, but by splitting this into a new method it makes the API clearer. (Note that existing plugins may continue to use
.config_complete for this work if they prefer.)
There is a new
.preconnect method available which is called just after the client makes a connection but before any NBD negotiation or TLS authentication is done. It can be used for early whitelisting or rate limiting of connections, and in particular is used by the new nbdkit-ip-filter(1).
CURLINFO_CONTENT_LENGTH_DOWNLOAD_T is used (if available) so that file sizes up to 63 bits should now work on all platforms (Pino Toscano and Adrian Ambrożewicz).
nbdkit is now compatible with OCaml 4.10.
nbdkit-memory-plugin(1) now supports
size=0 (Eric Blake).
Plugins which were actually added in nbdkit 1.0.0 are now documented as such properly.
Improved methods for probing plugins and filters are documented in nbdkit-probing(1).
Old plugins from nbdkit 1.0, 1.2, 1.8 and 1.12 are now bundled with the nbdkit sources and tested to try to ensure that they do not accidentally regress. Note these are included as binary blobs. See tests/old-plugins/README for more information about this, including how to delete these tests.
Various tests, especially ones which rely on timeouts, have been made more stable so they should not fail on slow or overloaded machines.
Many tests now use libnbd and nbdsh (instead of libguestfs and guestfish) as the test client. This should improve the performance of the tests for most people.
The --vsock option (added in nbdkit 1.16) can now be tested if the host is running Linux ≥ 5.6 (Stefano Garzarella).
You can use
./configure --disable-nbd-plugin to completely disable the NBD plugin.
The automake feature
subdir-objects is no longer used, which may improve compatibility on platforms with ancient and buggy automake (RHEL 7 being one such platform).
The explicit connection parameter passed around many functions in the server is now fetched from thread-local storage.
The server no longer calls the finalize method if prepare fails. Also failing to reopen the plugin from nbdkit-retry-filter(1) no longer hangs (Eric Blake).
git.orderfile was enhanced to make patches easier to read (Eric Blake).
Internal calls to methods like get_size, can_write will now no longer produce debug messages if the data is simply being returned from the internal cache (but calls into the plugin are still logged).
Authors of nbdkit 1.18:
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