Change thumbnail mounting dir to avoid nested mounts

[Rivers47]

Please describe your suggestion, and the problem it'd solve.
Currently the docker image mounts thumbnail to content/thumb which is very convoluted and LRRG will try to create a empty directory "thumb/ under content if user creates a thumbnail volume that mounts to content/thumb. Mounting a volume inside another bind mount should be avoided. I suggest either in tools/build/docker/Dockerfile remove

VOLUME [ "/home/koyomi/lanraragi/content/thumb" ]

alltogether and let user decide where thumbnails should be,
or change it to

VOLUME [ "/home/koyomi/lanraragi/thumb" ]

Additional context
none

[Difegue]

hmm, the idea with that mount was to keep the previous behavior where thumbnails were always in the content folder by default, but maybe I should just give up on that and have it in a fully separated folder for good.

[dix0nym]

TL;DR: I think I experienced the following problem because of the nested mount: No thumbnails on container restart.

My content folder is in a NFS mounted directory of the host system.
After each restart of the container, the thumbnails were missing. And it could only be fixed by running Generate missing thumbnails - even though all thumbnail should already exist.

I set up some logging in the serve_thumbnail function:

server_thumbnail with some logging

sub serve_thumbnail {

    my ( $self, $id ) = @_;

    my $logger = get_logger( "Thumbanil Serving", "lanraragi" );

    my $page = $self->req->param('page');
    $page = 0 unless $page;

    my $no_fallback = $self->req->param('no_fallback');
    $no_fallback = ( $no_fallback && $no_fallback eq "true" ) || "0";    # Prevent undef warnings by checking the variable first

    my $thumbdir        = LANraragi::Model::Config->get_thumbdir;
    my $use_jxl         = LANraragi::Model::Config->get_jxlthumbpages;
    my $format          = $use_jxl         ? 'jxl' : 'jpg';
    my $fallback_format = $format eq 'jxl' ? 'jpg' : 'jxl';

    # Thumbnails are stored in the content directory, thumb subfolder.
    # Another subfolder with the first two characters of the id is used for FS optimization.
    my $subfolder = substr( $id, 0, 2 );

    # Check for the page and set the appropriate thumbnail name and fallback thumbnail name
    my $thumbbase          = ( $page - 1 > 0 ) ? "$thumbdir/$subfolder/$id/$page" : "$thumbdir/$subfolder/$id";
    my $thumbname          = "$thumbbase.$format";
    my $fallback_thumbname = "$thumbbase.$fallback_format";

    # Check if the preferred format thumbnail exists, if not, try the alternate format
    unless ( -e $thumbname ) {
        $logger->info("thumbnail (preferred format) for $id: '$thumbname' does not exist! Trying fallback: '$fallback_thumbname'");
        $thumbname = $fallback_thumbname;
    }

    unless ( -e $thumbname ) {
        $logger->info("thumbnail (pf|fallback) for $id: '$thumbname' does not exist!");
        if ($no_fallback) {
            $logger->info("thumbnail fallback disabled for '$thumbname' ($id) - queue minion job");
            # Queue a minion job to generate the thumbnail. Thumbnail jobs have the lowest priority.
            my $job_id = $self->minion->enqueue( thumbnail_task => [ $thumbdir, $id, $page ] => { priority => 0, attempts => 3 } );
            $self->render(
                json => {
                    operation => "serve_thumbnail",
                    success   => 1,
                    job       => $job_id
                },
                status => 202    # 202 Accepted
            );
        } else {
            $logger->info("fallback enabled but no thumb found for '$thumbname' - serving noThumb.png for $id");
            # If the thumbnail doesn't exist, serve the default thumbnail.
            $self->render_file( filepath => "./public/img/noThumb.png" );
        }
        return;
    } else {
        $logger->info("thumbnail (pf|fallback) found for $id: $thumbname - serving");
        # Simply serve the thumbnail.
        $self->render_file( filepath => $thumbname );
    }
}

output:

As you can see on the screenshot -> the thumbnail actually did not exist! All other thumbnails and folder structure in content/thumb was also missing. But all archives were there in /home/koyomi/lanraragi/content.

I thought it could be a NFS limitation, as I currently have 27k archives in content. But I could not confirm that.

Another option could be a issue with the nested docker mounts. I moved the thumb and tried the following addition to my docker-compose.yaml:

    environment:
      LRR_THUMB_DIRECTORY: "/thumb"
   volumes:
      - /media/nfs-share/lanraragi/content:/home/koyomi/lanraragi/content
      - /media/nfs-share/lanraragi/thumb:/thumb

And all thumbnail were loading from the start! Separating content and thumb actually solved my issue.