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

[Fabian Grünbichler]

On March 26, 2025 3:20 pm, Max Carrara wrote:
> 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 at 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)

called when adding a storage config entry, before the new config gets 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)

called when updating a storage config entry, before the updated config
gets 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.

called when deleting a storage config entry, before the new storage
config gets written.

also called as part of error handling when undoing the addition of a new
storage config entry.

> +# 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
> +

should this describe what IMAGES are in the context of PVE? else as a
newcomer the difference between IMAGE here and VOLUME below might not
be clear..

> +=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

see above

> +
> +=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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