[pve-devel] [PATCH pmg-api v4] make tasklog downloadable in the PMG backend

[Daniel Tschlatscher <d.tschlatscher@proxmox.com>]

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.

I saw an opportunity here to clear some redundant code for displaying
the tasklog and replaced it with a call to dump_logfile(), akin to how
this is handled in pve-manager.

Signed-off-by: Daniel Tschlatscher <d.tschlatscher@proxmox.com>
---
Changes from v3:
* API parameter 'download' for directly streaming the file
* Added missing API parameter descriptions

 src/PMG/API2/Tasks.pm | 60 ++++++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 24 deletions(-)

diff --git a/src/PMG/API2/Tasks.pm b/src/PMG/API2/Tasks.pm
index 598fb4d..5a6f002 100644
--- a/src/PMG/API2/Tasks.pm
+++ b/src/PMG/API2/Tasks.pm
@@ -238,12 +238,19 @@ __PACKAGE__->register_method({
 		type => 'integer',
 		minimum => 0,
 		optional => 1,
+		description => "Start at this line when reading the tasklog",
 	    },
 	    limit => {
 		type => 'integer',
 		minimum => 0,
 		optional => 1,
+		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 => {
@@ -268,37 +275,42 @@ __PACKAGE__->register_method({
 	my ($task, $filename) = PVE::Tools::upid_decode($param->{upid}, 1);
 	raise_param_exc({ upid => "unable to parse worker upid" }) if !$task;
 
-	my $lines = [];
+	my $download = $param->{download} // 0;
 
-	my $restenv = PMG::RESTEnvironment->get();
+	if ($download) {
+	    die "Parameter 'download' can't be used with other parameters\n"
+		if (defined($param->{start}) || defined($param->{limit}));
 
-	my $fh = IO::File->new($filename, "r");
-	raise_param_exc({ upid => "no such task - unable to open file - $!" }) if !$fh;
+	    my $fh;
+	    my $use_compression = ( -s $filename ) > 1024;
 
-	my $start = $param->{start} || 0;
-	my $limit = $param->{limit} || 50;
-	my $count = 0;
-	my $line;
-	while (defined ($line = <$fh>)) {
-	    next if $count++ < $start;
-	    next if $limit <= 0;
-	    chomp $line;
-	    push @$lines, { n => $count, t => $line};
-	    $limit--;
-	}
+	    # 1024 is a practical cutoff for the size distribution of our log files.
+	    if ($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";
+	    }
 
-	close($fh);
+	    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;
 
-	# HACK: ExtJS store.guaranteeRange() does not like empty array
-	# so we add a line
-	if (!$count) {
-	    $count++;
-	    push @$lines, { n => $count, t => "no content"};
-	}
+	    my ($count, $lines) = PVE::Tools::dump_logfile($filename, $start, $limit);
 
-	$restenv->set_result_attrib('total', $count);
+	    PMG::RESTEnvironment->get()->set_result_attrib('total', $count);
 
-	return $lines;
+	    return $lines;
+	}
     }});
 
 
-- 
2.30.2