[pve-devel] [PATCH v1 pve-storage 1/8] pluginbase: introduce PVE::Storage::PluginBase with doc scaffold

[Max Carrara <m.carrara@proxmox.com>]

Add PVE::Storage::PluginBase, which defines stubs for all methods that
storage plugins should implement in order to conform to our plugin
API. This makes it much easier for (third-party) developers to see
which methods should be implemented.

PluginBase is inserted into the inheritance chain between
PVE::Storage::Plugin and PVE::SectionConfig instead of letting the
Plugin module inherit from SectionConfig directly. This keeps the
inheritance chain linear, avoiding multiple inheritance.

Also provide a scaffold for documentation. Preserve pre-existing
comments for context's sake.

Signed-off-by: Max Carrara <m.carrara@proxmox.com>
---
 src/PVE/Storage/Makefile      |   1 +
 src/PVE/Storage/Plugin.pm     |   2 +-
 src/PVE/Storage/PluginBase.pm | 328 ++++++++++++++++++++++++++++++++++
 3 files changed, 330 insertions(+), 1 deletion(-)
 create mode 100644 src/PVE/Storage/PluginBase.pm

diff --git a/src/PVE/Storage/Makefile b/src/PVE/Storage/Makefile
index ce3fd68..f2cdb66 100644
--- a/src/PVE/Storage/Makefile
+++ b/src/PVE/Storage/Makefile
@@ -1,6 +1,7 @@
 SOURCES= \
 	Common.pm \
 	Plugin.pm \
+	PluginBase.pm \
 	DirPlugin.pm \
 	LVMPlugin.pm \
 	NFSPlugin.pm \
diff --git a/src/PVE/Storage/Plugin.pm b/src/PVE/Storage/Plugin.pm
index 65cf43f..df6882a 100644
--- a/src/PVE/Storage/Plugin.pm
+++ b/src/PVE/Storage/Plugin.pm
@@ -19,7 +19,7 @@ use PVE::Storage::Common;
 
 use JSON;
 
-use base qw(PVE::SectionConfig);
+use parent qw(PVE::Storage::PluginBase);
 
 use constant KNOWN_COMPRESSION_FORMATS =>  ('gz', 'lzo', 'zst', 'bz2');
 use constant COMPRESSOR_RE => join('|', KNOWN_COMPRESSION_FORMATS);
diff --git a/src/PVE/Storage/PluginBase.pm b/src/PVE/Storage/PluginBase.pm
new file mode 100644
index 0000000..e56aa72
--- /dev/null
+++ b/src/PVE/Storage/PluginBase.pm
@@ -0,0 +1,328 @@
+=head1 NAME
+
+C<PVE::Storage::PluginBase> - Storage Plugin API Interface
+
+=head1 DESCRIPTION
+
+=cut
+
+package PVE::Storage::PluginBase;
+
+use strict;
+use warnings;
+
+use Carp qw(croak);
+
+use parent qw(PVE::SectionConfig);
+
+=head1 PLUGIN INTERFACE METHODS
+
+=cut
+
+=head2 PLUGIN DEFINITION
+
+=cut
+
+sub type {
+    croak "implement me in sub-class\n";
+}
+
+sub properties {
+    my ($class) = @_;
+    return $class->SUPER::properties();
+}
+
+sub options {
+    my ($class) = @_;
+    return $class->SUPER::options();
+}
+
+sub plugindata {
+    my ($class) = @_;
+    return $class->SUPER::plugindata();
+}
+
+sub private {
+    croak "implement me in sub-class\n";
+}
+
+=head2 GENERAL
+
+=cut
+
+sub check_connection {
+    my ($class, $storeid, $scfg) = @_;
+
+    return 1;
+}
+
+sub activate_storage {
+    my ($class, $storeid, $scfg, $cache) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub deactivate_storage {
+    my ($class, $storeid, $scfg, $cache) = @_;
+
+    return;
+}
+
+sub status {
+    my ($class, $storeid, $scfg, $cache) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub cluster_lock_storage {
+    my ($class, $storeid, $shared, $timeout, $func, @param) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub parse_volname {
+    my ($class, $volname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub get_subdir {
+    my ($class, $scfg, $vtype) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub filesystem_path {
+    my ($class, $scfg, $volname, $snapname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub path {
+    my ($class, $scfg, $volname, $storeid, $snapname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub find_free_diskname {
+    my ($class, $storeid, $scfg, $vmid, $fmt, $add_fmt_suffix) = @_;
+    croak "implement me in sub-class\n";
+}
+
+=head2 HOOKS
+
+=cut
+
+# called during addition of storage (before the new storage config got written)
+# die to abort addition if there are (grave) problems
+# NOTE: runs in a storage config *locked* context
+sub on_add_hook {
+    my ($class, $storeid, $scfg, %param) = @_;
+    return undef;
+}
+
+# called during storage configuration update (before the updated storage config got written)
+# die to abort the update if there are (grave) problems
+# NOTE: runs in a storage config *locked* context
+sub on_update_hook {
+    my ($class, $storeid, $scfg, %param) = @_;
+    return undef;
+}
+
+# called during deletion of storage (before the new storage config got written)
+# and if the activate check on addition fails, to cleanup all storage traces
+# which on_add_hook may have created.
+# die to abort deletion if there are (very grave) problems
+# NOTE: runs in a storage config *locked* context
+sub on_delete_hook {
+    my ($class, $storeid, $scfg) = @_;
+    return undef;
+}
+
+=head2 IMAGE OPERATIONS
+
+=cut
+
+sub list_images {
+    my ($class, $storeid, $scfg, $vmid, $vollist, $cache) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub create_base {
+    my ($class, $storeid, $scfg, $volname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub clone_image {
+    my ($class, $scfg, $storeid, $volname, $vmid, $snap) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub alloc_image {
+    my ($class, $storeid, $scfg, $vmid, $fmt, $name, $size) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub free_image {
+    my ($class, $storeid, $scfg, $volname, $isBase, $format) = @_;
+    croak "implement me in sub-class\n";
+}
+
+=head2 VOLUME OPERATIONS
+
+=cut
+
+sub list_volumes {
+    my ($class, $storeid, $scfg, $vmid, $content_types) = @_;
+    croak "implement me in sub-class\n";
+}
+
+# Returns undef if the attribute is not supported for the volume.
+# Should die if there is an error fetching the attribute.
+# Possible attributes:
+# notes     - user-provided comments/notes.
+# protected - not to be removed by free_image, and for backups, ignored when pruning.
+sub get_volume_attribute {
+    my ($class, $scfg, $storeid, $volname, $attribute) = @_;
+    croak "implement me in sub-class\n";
+}
+
+# Dies if the attribute is not supported for the volume.
+sub update_volume_attribute {
+    my ($class, $scfg, $storeid, $volname, $attribute, $value) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_size_info {
+    my ($class, $scfg, $storeid, $volname, $timeout) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_resize {
+    my ($class, $scfg, $storeid, $volname, $size, $running) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_snapshot {
+    my ($class, $scfg, $storeid, $volname, $snap) = @_;
+    croak "implement me in sub-class\n";
+}
+
+# Returns a hash with the snapshot names as keys and the following data:
+# id        - Unique id to distinguish different snapshots even if the have the same name.
+# timestamp - Creation time of the snapshot (seconds since epoch).
+# Returns an empty hash if the volume does not exist.
+sub volume_snapshot_info {
+    my ($class, $scfg, $storeid, $volname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+# Asserts that a rollback to $snap on $volname is possible.
+# If certain snapshots are preventing the rollback and $blockers is an array
+# reference, the snapshot names can be pushed onto $blockers prior to dying.
+sub volume_rollback_is_possible {
+    my ($class, $scfg, $storeid, $volname, $snap, $blockers) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_snapshot_rollback {
+    my ($class, $scfg, $storeid, $volname, $snap) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_snapshot_delete {
+    my ($class, $scfg, $storeid, $volname, $snap, $running) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_snapshot_needs_fsfreeze {
+    croak "implement me in sub-class\n";
+}
+
+sub storage_can_replicate {
+    my ($class, $scfg, $storeid, $format) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_has_feature {
+    my ($class, $scfg, $feature, $storeid, $volname, $snapname, $running, $opts) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub map_volume {
+    my ($class, $storeid, $scfg, $volname, $snapname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub unmap_volume {
+    my ($class, $storeid, $scfg, $volname, $snapname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub activate_volume {
+    my ($class, $storeid, $scfg, $volname, $snapname, $cache) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub deactivate_volume {
+    my ($class, $storeid, $scfg, $volname, $snapname, $cache) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub rename_volume {
+    my ($class, $scfg, $storeid, $source_volname, $target_vmid, $target_volname) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub prune_backups {
+    my ($class, $scfg, $storeid, $keep, $vmid, $type, $dryrun, $logfunc) = @_;
+    croak "implement me in sub-class\n";
+}
+
+=head2 IMPORTS AND EXPORTS
+
+=cut
+
+# Import/Export interface:
+#   Any path based storage is assumed to support 'raw' and 'tar' streams, so
+#   the default implementations will return this if $scfg->{path} is set,
+#   mimicking the old PVE::Storage::storage_migrate() function.
+#
+# Plugins may fall back to PVE::Storage::Plugin::volume_{export,import}...
+#   functions in case the format doesn't match their specialized
+#   implementations to reuse the raw/tar code.
+#
+# Format specification:
+#   The following formats are all prefixed with image information in the form
+#   of a 64 bit little endian unsigned integer (pack('Q<')) in order to be able
+#   to preallocate the image on storages which require it.
+#
+#   raw+size: (image files only)
+#     A raw binary data stream such as produced via `dd if=TheImageFile`.
+#   qcow2+size, vmdk: (image files only)
+#     A raw qcow2/vmdk/... file such as produced via `dd if=some.qcow2` for
+#     files which are already in qcow2 format, or via `qemu-img convert`.
+#     Note that these formats are only valid with $with_snapshots being true.
+#   tar+size: (subvolumes only)
+#     A GNU tar stream containing just the inner contents of the subvolume.
+#     This does not distinguish between the contents of a privileged or
+#     unprivileged container. In other words, this is from the root user
+#     namespace's point of view with no uid-mapping in effect.
+#     As produced via `tar -C vm-100-disk-1.subvol -cpf TheOutputFile.dat .`
+
+# Export a volume into a file handle as a stream of desired format.
+sub volume_export {
+    my ($class, $scfg, $storeid, $fh, $volname, $format, $snapshot, $base_snapshot, $with_snapshots) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_export_formats {
+    my ($class, $scfg, $storeid, $volname, $snapshot, $base_snapshot, $with_snapshots) = @_;
+    croak "implement me in sub-class\n";
+}
+
+# Import data from a stream, creating a new or replacing or adding to an existing volume.
+sub volume_import {
+    my ($class, $scfg, $storeid, $fh, $volname, $format, $snapshot, $base_snapshot, $with_snapshots, $allow_rename) = @_;
+    croak "implement me in sub-class\n";
+}
+
+sub volume_import_formats {
+    my ($class, $scfg, $storeid, $volname, $snapshot, $base_snapshot, $with_snapshots) = @_;
+    croak "implement me in sub-class\n";
+}
+
+1;
-- 
2.39.5



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