From 6e76f8e6cc8195b3cfc32b4d7f13f8f62db81785 Mon Sep 17 00:00:00 2001
From: Roman Gershman <roman@dragonflydb.io>
Date: Mon, 9 Oct 2023 20:08:37 +0300
Subject: [PATCH] fix: logrotate for dragonfly logs (#1972)

The new logrotate settings assume that dragonfly closes a log file
once it grows to large. It never rotates file that is currently open for writing.

Specifically logrotate:

1. rotate only log files
2. skip those that are currently open by as process.
3. compresses using zstd which is more cpu efficient than gzip
4. does not truncate/create old files as 0-sized blobs - just renames them

Fixes #1935

Signed-off-by: Roman Gershman <roman@dragonflydb.io>
---
 src/server/dfly_main.cc                    |  3 +++
 tools/packaging/debian/control             |  2 +-
 tools/packaging/debian/dragonfly.conf      |  1 +
 tools/packaging/debian/dragonfly.logrotate | 25 +++++++++++++++++++---
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/server/dfly_main.cc b/src/server/dfly_main.cc
index 87296bf2b..897fe5ad8 100644
--- a/src/server/dfly_main.cc
+++ b/src/server/dfly_main.cc
@@ -787,8 +787,11 @@ Usage: dragonfly [FLAGS]
   };
 
   absl::SetFlagsUsageConfig(config);
+  google::InitGoogleLogging(argv[0]);
+  google::SetLogFilenameExtension(".log");
 
   MainInitGuard guard(&argc, &argv);
+
   ParseFlagsFromEnv();
 
   PrintBasicUsageInfo();
diff --git a/tools/packaging/debian/control b/tools/packaging/debian/control
index 2a4e2a6bf..f62ae3f15 100644
--- a/tools/packaging/debian/control
+++ b/tools/packaging/debian/control
@@ -7,6 +7,6 @@ Vcs-Git: https://github.com/dragonflydb/dragonfly
 
 Package: dragonfly
 Architecture: amd64 arm64
-Depends: libc6, openssl, adduser
+Depends: libc6, openssl, adduser, zstd
 Homepage: https://dragonflydb.io
 Description: A fast in-memory store that is fully compatible with Redis™* and Memcached.
diff --git a/tools/packaging/debian/dragonfly.conf b/tools/packaging/debian/dragonfly.conf
index 564fe9507..9226ee696 100644
--- a/tools/packaging/debian/dragonfly.conf
+++ b/tools/packaging/debian/dragonfly.conf
@@ -1,4 +1,5 @@
 --pidfile=/var/run/dragonfly/dragonfly.pid
 --log_dir=/var/log/dragonfly
 --dir=/var/lib/dragonfly
+--max_log_size=20
 --version_check=true
diff --git a/tools/packaging/debian/dragonfly.logrotate b/tools/packaging/debian/dragonfly.logrotate
index 84214927e..2047f613e 100644
--- a/tools/packaging/debian/dragonfly.logrotate
+++ b/tools/packaging/debian/dragonfly.logrotate
@@ -1,7 +1,26 @@
-/var/log/dragonfly/dragonfly* {
-        weekly
+# installed by debhelper by convention into /etc/logrotate.d/
+
+/var/log/dragonfly/dragonfly*.log {
+        daily
         missingok
-        rotate 12
+
         compress
+        compresscmd zstd
+        uncompresscmd unzstd
+        compressext .zst
         notifempty
+
+# do not create an empty file after the rotation.
+        nocreate
+        prerotate
+                if lsof -t $1 > /dev/null; then
+                # file is open. Skipping rotation."
+                exit 1
+                fi
+        endscript
+
+# Possible hook to upload rotated logs to cloud storage.
+        postrotate
+                echo "TBD: POSTROTATE"
+        endscript
 }