[pmg-devel] [PATCH manager v3] make task log downloadable in the PVE manager backend

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

The read tasklog API call now streams the log file if the limit
parameter is set to 0. If not, it should behave the same as before.
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>
---

changes from v2
* replaced helper call with inline implementation
* changed compression cutoff to 1024
* replaced stat($filename)→size call with "-s"

 PVE/API2/Tasks.pm | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/PVE/API2/Tasks.pm b/PVE/API2/Tasks.pm
index 9cd1e56b..3bc00704 100644
--- a/PVE/API2/Tasks.pm
+++ b/PVE/API2/Tasks.pm
@@ -349,7 +349,7 @@ __PACKAGE__->register_method({
 		minimum => 0,
 		default => 50,
 		optional => 1,
-		description => "The maximum amount of lines that should be printed.",
+		description => "The maximum amount of lines that should be printed. A limit of 0 streams the file directly, otherwise lines are json encoded.",
 	    },
 	},
     },
@@ -387,6 +387,29 @@ __PACKAGE__->register_method({
 	    $rpcenv->check($user, "/nodes/$node", [ 'Sys.Audit' ]);
 	}
 
+	if ($limit == 0) {
+	    # 1024 is a practical cutoff for the size distribution of our log files.
+	    my $use_compression = ( -s $filename ) > 1024;
+
+	    my $fh;
+	    if ($use_compression) {
+		open($fh, "-|", "/usr/bin/gzip", "-c", "$filename")
+		    or die "Could not create compressed file stream for $filename - $!";
+	    } else {
+		open($fh, '<', $filename) or die "Could not open file $filename - $!";
+	    }
+
+	    return {
+		download => {
+		    fh => $fh,
+		    stream => 1,
+		    'content-encoding' => $use_compression ? 'gzip' : undef,
+		    'content-type' => "text/plain",
+		    'content-disposition' => "attachment; filename=\"".$param->{upid}."\"",
+		},
+	    },
+	}
+
 	my ($count, $lines) = PVE::Tools::dump_logfile($filename, $start, $limit);
 
 	$rpcenv->set_result_attrib('total', $count);
-- 
2.30.2