linux: guard duplicated instance (not adding a new option)

Closes: fluent#611

Before:

We can launch Fluentd by /usr/sbin/fluentd even though fluentd service
is running.

Launching multiple Fluentd with the same config may cause
inconsistency of the buffers or the pos files.

After:

We can't launch Fluentd by /usr/sbin/fluentd with the default config
path if fluentd service is running.  If one of the following options is
specified, we can execute fluentd as before.

* --config (-c)
* --dry-run

Signed-off-by: Kentaro Hayashi <hayashi@clear-code.com>

fluent-package/apt/systemd-test/install-newly.sh

@@ -28,6 +28,14 @@ sudo fluent-gem install fluent-plugin-concat
 /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
 test $(find /tmp/ -name gem_local_list.output | xargs cat) = "fluent-plugin-concat"
 
+# Test: Guard duplicated instance
+if [ "$1" = "local" ]; then
+ # FIXME: until guard feature was released, skip v5 and lts.
+ (! sudo /usr/sbin/fluentd)
+ (! sudo /usr/sbin/fluentd -v)
+ sudo /usr/sbin/fluentd --dry-run
+fi
+
 sudo apt remove -y fluent-package
 
 case ${code_name} in

fluent-package/apt/systemd-test/update-from-v4.sh

@@ -84,6 +84,12 @@ sudo fluent-gem install fluent-plugin-concat
 /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
 test $(find /tmp/ -name gem_local_list.output | xargs cat) = "fluent-plugin-concat"
 
+# Test: Guard duplicated instance
+(! sudo /usr/sbin/fluentd)
+(! sudo /usr/sbin/td-agent)
+(! sudo /usr/sbin/fluentd -v)
+sudo /usr/sbin/fluentd --dry-run
+
 # Uninstall
 sudo apt remove -y fluent-package
 (! systemctl status --no-pager td-agent)

fluent-package/apt/systemd-test/update-to-next-version-with-backward-compat-for-v4.sh

@@ -80,6 +80,12 @@ sleep 3
 test -e /var/log/fluent/fluentd.log
 (! grep -e '\[error\]' -e '\[fatal\]' /var/log/fluent/fluentd.log)
 
+# Test: Guard duplicated instance
+(! sudo /usr/sbin/fluentd)
+(! sudo /usr/sbin/td-agent)
+(! sudo /usr/sbin/fluentd -v)
+sudo /usr/sbin/fluentd --dry-run
+
 # Uninstall
 sudo apt remove -y fluent-package
 (! systemctl status --no-pager td-agent)

fluent-package/apt/systemd-test/update-to-next-version.sh

@@ -49,6 +49,12 @@ sleep 3
 test -e /var/log/fluent/fluentd.log
 (! grep -q -e '\[warn\]' -e '\[error\]' -e '\[fatal\]' /var/log/fluent/fluentd.log)
 
+# Test: Guard duplicated instance
+(! sudo /usr/sbin/fluentd)
+(! sudo /usr/sbin/td-agent)
+(! sudo /usr/sbin/fluentd -v)
+sudo /usr/sbin/fluentd --dry-run
+
 # Uninstall
 sudo apt remove -y fluent-package
 (! systemctl status --no-pager td-agent)

fluent-package/templates/usr/sbin/fluentd.erb

@@ -12,4 +12,38 @@ if ARGV.include?("--version")
  puts "fluent-package #{PACKAGE_VERSION} fluentd #{Fluent::VERSION} (#{FLUENTD_REVISION})"
  exit 0
 end
+
+class DuplicateInstanceChecker
+ def running_fluentd?
+ `systemctl is-active fluentd`
+ return true if $?.exitstatus == 0
+ false
+ end
+
+ def prevent_duplicate_launch?
+ unless running_fluentd?
+ return false
+ end
+ true
+ end
+end
+
+if RUBY_PLATFORM =~ /linux/
+ checker = DuplicateInstanceChecker.new
+ if checker.prevent_duplicate_launch?
+ unless ARGV.include?("-c") or ARGV.include?("--config") or ARGV.include?("--dry-run")
+ puts("Error: Can't start duplicate Fluentd instance with the default config.")
+ if ARGV.include?("-v")
+ puts("To take the version, please use '--version', not '-v' ('--verbose').")
+ end
+ puts <<EOS
+To start Fluentd, please do one of the following:
+(Caution: Please be careful not to start multiple instances with the same config.)
+- Stop the Fluentd service 'fluentd'.
+- Specify the config path explicitly by '-c' ('--config').
+EOS
+ exit 2
+ end
+ end
+end
 load "<%= install_path %>/bin/fluentd"

fluent-package/yum/systemd-test/install-newly.sh

@@ -51,6 +51,10 @@ if [ $1 = "local" ]; then
  sudo $DNF install -y tar findutils
  sudo /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
  test $(find /tmp/ -name gem_local_list.output | xargs cat) = "fluent-plugin-concat"
+ # FIXME: until guard feature was released, skip v5 and lts.
+ (! sudo /usr/sbin/fluentd)
+ (! sudo /usr/sbin/fluentd -v)
+ sudo /usr/sbin/fluentd --dry-run
 fi
 
 sudo $DNF remove -y fluent-package

fluent-package/yum/systemd-test/update-from-v4.sh

@@ -96,6 +96,12 @@ sudo fluent-gem install fluent-plugin-concat
 sudo /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
 test $(find /tmp/ -name gem_local_list.output | xargs cat) = "fluent-plugin-concat"
 
+# Test: Guard duplicated instance
+(! sudo /usr/sbin/fluentd)
+(! sudo /usr/sbin/td-agent)
+(! sudo /usr/sbin/fluentd -v)
+sudo /usr/sbin/fluentd --dry-run
+
 # Uninstall
 sudo $DNF remove -y fluent-package
 sudo systemctl daemon-reload

fluent-package/yum/systemd-test/update-to-next-version-with-backward-compat-for-v4.sh

@@ -115,6 +115,12 @@ sudo fluent-gem install fluent-plugin-concat
 sudo /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
 test $(find /tmp/ -name gem_local_list.output | xargs cat) = "fluent-plugin-concat"
 
+# Test: Guard duplicated instance
+(! sudo /usr/sbin/fluentd)
+(! sudo /usr/sbin/td-agent)
+(! sudo /usr/sbin/fluentd -v)
+sudo /usr/sbin/fluentd --dry-run
+
 # Uninstall
 sudo $DNF remove -y fluent-package
 (! systemctl status --no-pager td-agent)

fluent-package/yum/systemd-test/update-to-next-version.sh

@@ -73,6 +73,12 @@ sudo fluent-gem install fluent-plugin-concat
 sudo /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
 test $(find /tmp/ -name gem_local_list.output | xargs cat) = "fluent-plugin-concat"
 
+# Test: Guard duplicated instance
+(! sudo /usr/sbin/fluentd)
+(! sudo /usr/sbin/td-agent)
+(! sudo /usr/sbin/fluentd -v)
+sudo /usr/sbin/fluentd --dry-run
+
 # Uninstall
 sudo $DNF remove -y fluent-package
 sudo systemctl daemon-reload