make task log downloadable in the PVE manager backend

The read_tasklog API call now stream the whole log file if the query
parameter 'download' is set to true.
This is done in preparation for the task log download button to be
added in the TaskViewer.

Signed-off-by: Daniel Tschlatscher <d.tschlatscher@proxmox.com>
Tested-by: Stefan Sterz <s.sterz@proxmox.com>
Reviewed-by: Stefan Sterz <s.sterz@proxmox.com>

diff --git a/PVE/API2/Tasks.pm b/PVE/API2/Tasks.pm
index 9cd1e56b607c7570a2c4636df5ed4e62130e8e06..e541dd55cb882ffc5b7ed591043b064f5dae9fcf 100644 (file)
--- a/PVE/API2/Tasks.pm
+++ b/PVE/API2/Tasks.pm
@@ -342,15 +342,20 @@ __PACKAGE__->register_method({
                minimum => 0,
                default => 0,
                optional => 1,
-               description => "The line number to start printing at.",
+               description => "Start at this line when reading the tasklog",
            },
            limit => {
                type => 'integer',
                minimum => 0,
                default => 50,
                optional => 1,
-               description => "The maximum amount of lines that should be printed.",
+               description => "The amount of lines to read from the tasklog.",
            },
+           download => {
+               type => 'boolean',
+               optional => 1,
+               description => "Whether the tasklog file should be downloaded. This parameter can't be used in conjunction with other parameters",
+           }
        },
     },
     returns => {
@@ -378,8 +383,6 @@ __PACKAGE__->register_method({
        my $rpcenv = PVE::RPCEnvironment::get();
        my $user = $rpcenv->get_user();
        my $node = $param->{node};
-       my $start = $param->{start} // 0;
-       my $limit = $param->{limit} // 50;
 
        $convert_token_task->($task);
 
@@ -387,11 +390,43 @@ __PACKAGE__->register_method({
            $rpcenv->check($user, "/nodes/$node", [ 'Sys.Audit' ]);
        }
 
-       my ($count, $lines) = PVE::Tools::dump_logfile($filename, $start, $limit);
+       my $download = $param->{download} // 0;
 
-       $rpcenv->set_result_attrib('total', $count);
+       if ($download) {
+           if (defined($param->{start}) || defined($param->{limit})) {
+               die "Parameter 'download' can't be used with other parameters\n";
+           }
+
+           my $fh;
+           my $use_compression = ( -s $filename ) > 1024;
 
-       return $lines;
+           # 1024 is a practical cutoff for the size distribution of our log files.
+           if ($use_compression) {
+               open($fh, "-|", "/usr/bin/gzip", "-c", "$filename")
+                   or die "Could not create compressed file stream for file '$filename' - $!\n";
+           } else {
+               open($fh, '<', $filename) or die "Could not open file '$filename' - $!\n";
+           }
+
+           return {
+               download => {
+                   fh => $fh,
+                   stream => 1,
+                   'content-encoding' => $use_compression ? 'gzip' : undef,
+                   'content-type' => "text/plain",
+                   'content-disposition' => "attachment; filename=\"".$param->{upid}."\"",
+               },
+           },
+       } else {
+           my $start = $param->{start} // 0;
+           my $limit = $param->{limit} // 50;
+
+           my ($count, $lines) = PVE::Tools::dump_logfile($filename, $start, $limit);
+
+           $rpcenv->set_result_attrib('total', $count);
+
+           return $lines;
+       }
     }});