On August 29, 2025, we released fluent-package v6 as a new series of stable packages.
Fluent Package v6 LTS is a long-term support (LTS), stable package of Fluentd.
Fluent Package v5 LTS will reach end of support at the end of 2025. As its successor, Fluent Package v6 LTS will be supported until at least the end of 2027.
For more details, see the following article:
As an example, you can upgrade with the following steps:
Below are details for each step.
If your current version (before upgrade) is Fluent Package v5.0.2 or later (v5.0.3 for Windows), you can use the bundled fluent-diagtool to list manually installed plugins.
Run the following command:
$ /opt/fluent/bin/fluent-diagtool -t fluentd -o /tmp
-t fluentd: required-o /tmp: specifies the output directory for results (you can choose any directory)The tool outputs various information to standard output. The following section shows the list of manually installed plugins:
(...)
2025-07-17 08:13:31 +0000: [Diagtool] [INFO] [Collect] fluent-package manually installed gem information is stored in /tmp/20250717081331/output/gem_local_list.output
2025-07-17 08:13:31 +0000: [Diagtool] [INFO] [Collect] fluent-package manually installed gems:
2025-07-17 08:13:31 +0000: [Diagtool] [INFO] [Collect] * fluent-plugin-remote_syslog
(...)
In this example, the only manually installed plugin is fluent-plugin-remote_syslog.
The list is also saved to a file:
/{output_directory}/{execution_timestamp}/output/gem_local_list.outputFor the above case, the list was saved to /tmp/20250717081331/output/gem_local_list.output.
If you are using a version earlier than v5.0.2, the bundled fluent-diagtool is outdated.
Please update it in advance:
$ sudo fluent-gem install fluent-diagtool
If you cannot update fluent-diagtool, obtain the list of plugins with:
$ fluent-gem list fluent-plugin
Note:
On fluent-package v5.0.2 for Windows or earlier, fluent-diagtool is not available due to a known issue.
Use fluent-gem list fluent-plugin instead.
Stop any running Fluentd service(s). If multiple Fluentd services are running, stop them in the order: forwarders first, then aggregators.
On Windows, back up registry settings needed for rollback. Run the following command in PowerShell or Command Prompt as an administrator:
> reg export HKLM\System\CurrentControlSet\Services\fluentdwinsvc C:\fluent-package-5_fluentdwinsvc.reg
Install Fluent Package v6 LTS.
Example for RPM Package (Red Hat Linux):
$ curl -fsSL https://fluentd.cdn.cncf.io/sh/install-redhat-fluent-package6-lts.sh | sh
Please refer to the official documentation for each environment:
The manually installed plugins need to be reinstalled. Reinstall the plugins identified in step 1.
Example:
$ sudo fluent-gem install fluent-plugin-remote_syslog
Restart the Fluentd service(s) you stopped in step 2. If multiple services exist, start them in the order from aggregators to forwarders.
Note: Zero-Downtime Update Settings (non-Windows)
From the next update onward, you can perform upgrades without stopping the service using the zero-downtime update feature (not supported on Windows).
You can configure how Fluentd restarts after an update:
This setting can be changed anytime and does not require restarting Fluentd itself.
For details, see:
Stop running Fluentd services, in the order from forwarders to aggregators.
On Linux, simply reinstall Fluent Package v5 LTS on top of v6. No need to uninstall v6 beforehand. On Windows, uninstall Fluent Package v6 LTS first, then install v5 LTS.
Manually installed plugins remain on the system, so after rollback they are still available. No reinstallation is required.
On Windows, restore the registry with the following command (admin PowerShell or Command Prompt):
> reg import C:\fluent-package-5_fluentdwinsvc.reg
This restores Windows service auto-start settings and startup command-line arguments.
Restart the stopped Fluentd services in opposite order: aggregators first, then forwarders.
Please see the download page.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 reached EOL in Dec, 2023.
And fluent-package v5 will reach EOL in end of 2025.
We strongly recommend upgrading to fluent-package v6 LTS.
We have been posting information about Fluentd in Japanese on @fluentd_jp. We would appreciate it if you followed our X account.
Hi users!
We're excited to announce the release of fluent-package v6.0.0 !
This is the first release of the v6 LTS series, and it will be supported until the end of 2027.
We strongly recommend upgrading to fluent-package v6 LTS!
Fluent Package v6 LTS is a long-term support (LTS), stable package of Fluentd.
The conventional Fluentd project official package, td-agent, reached its end of support at the end of 2023. Fluent Package has been officially developed and distributed by the Fluentd project since the end of August 2023 as its successor package.
The current LTS version, Fluent Package v5 LTS, will reach end of support at the end of 2025. As the next LTS version, Fluent Package v6 LTS will be supported until at least the end of 2027.
In LTS versions, we only perform bug fixes and security fixes over a pre-announced long-term period (minimum 2 years). Therefore, there are two advantages for long-term stable operations:
For detailed support schedule information, please see Scheduled support lifecycle announcement about Fluent Package v6.
This release includes many improvements for long-term stable operations. The main improvements are as follows:
While Fluent Package v5 LTS bundled Fluentd v1.16, v6 LTS moves to Fluentd v1.19. This makes the following new features available:
For more detailed changes since v1.16, see:
Starting from v6 LTS, zero-downtime updates are available. This feature allows you to safely execute configuration file reloading and Fluentd restarts with zero downtime (Windows not supported).
For more details, see the following articles and try out this feature:
Fluent Package v6 supports the following platforms:
This release supports transferring OpenTelemetry data over HTTP/HTTPS. For configuration methods and other details, please see the plugin README.
We also provide a sample for quick testing.
We've improved the system to preserve auto-start configuration and Windows service (fluentdwinsvc) command line options during updates.
This eliminates the need for reconfiguration that was previously required during updates.
In addition, manually installed plugins still need to be reinstalled when updating an LTS version. Starting from this release, plugins will be automatically reinstalled during future updates when using the zero-downtime update feature (Windows not supported). This will make future updates easier.
fluent-plugin-fluent-package-update-notifier plugin
fluent-plugin-obsolete-plugins plugin
fluent-plugin-systemd plugin
SIGABORT error.Please see the download page.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 reached EOL in Dec, 2023.
And fluent-package v5 will reach EOL in end of 2025.
We strongly recommend upgrading to fluent-package v6 LTS.
We have been posting information about Fluentd in Japanese on @fluentd_jp. We would appreciate it if you followed our X account.
Hi users!
We have released fluent-package v5.0.7. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This is a maintenance release of v5.0.x LTS series. Bundled Fluentd was updated to 1.16.9.
We recommend upgrading to fluent-package v5.0.7!
With an old gem, it caused an exception after FIPS enabled in OpenSSL. We have updated the bundled openssl gem to 3.3.0 to solve the issue.
There were memory leaks under conditions where exceptions frequently occurred during communication between Elasticsearch and fluent-plugin-elasticsearch. The issue was fixed in fluent-plugin-elasticsearch v5.4.4 and bundled into fluent-package v5.0.7.
Please see the download page.
We plan to ship the next LTS version of fluent-package v5.0.8 on September, 2025. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
We have been posting information about Fluentd in Japanese on @fluentd_jp. We would appreciate it if you followed the X account.
Hi users!
We have released fluent-package v5.0.6. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This is a maintenance release of v5.0.x LTS series. Bundled Fluentd was updated to 1.16.7.
We recommend upgrading to fluent-package v5.0.6!
In this release, known Windows issues were fixed.
In the previous versions, there had been a known issue that fluent-package could not keep some registry values when upgrading.
Thus, if you modify Fluentd service (fluentdwinsvc) related registry,
you need to restore your configuration after upgrading.
Since v5.0.6, fluent-package was fixed to keep some registry values during upgrading package.
Here is the target registry which will be kept during upgrading fluent-package:
StartDelayedAutostartfluentdopt (logging path might be modified by users)In most cases, fluent-package user might want to keep fluentdopt because
it stores additional command line option parameters.
In this release, bundled Fluentd v1.16.7 also contains the fixes for Windows.
NoMethodError of --daemon optionSee Fluentd v1.16.7 has been released blog article in details.
Please see the download page.
We plan to ship the next LTS version of fluent-package v5.0.7 on June, 2025. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
Hi users!
We have released fluent-package v5.2.0. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This release is a new release of v5.2 series.
GEM_HOME/GEM_PATH in fluentd.batPreviously, when upgrading the fluent-package, you had to stop the fluentd service, install the new version of the fluent-package, then install any necessary plugins, and finally restart the fluentd service.
Starting from fluent-package v5.2.0, we have introduced the zero-downtime restart feature that automatically installs the required plugins during the upgrade process and allows you to upgrade Fluentd without interrupting the logging service.
Please refer to "Advisory for upgrading with zero-downtime".
In the previous versions of msgpack gem, there was a possibility that cause DoS (Denial Of Service) when crafted message was sent to Fluentd.
When that message was sent, it might cause "NoMemoryError" on Fluentd because there is a case that msgpack try to pre-allocate huge amount of memories.
Above behavior was fixed not to pre-allocate over 32k entries (limit pre-allocated amount of memories) in msgpack 1.7.3 and bundled.
GEM_HOME/GEM_PATH in fluentd.batIn the previous versions, fluentd.bat doesn't set GEMHOME/GEMPATH explicitly.
If users set custom GEM_HOME / GEM_PATH environment variables, the
batch file will not work as expected. Therefore, this patch will set
the appropriate values in the batch file.
We have changed so that Fluentd does not restart when the needrestart package is installed.
fluent-package v5.2.0 places /etc/needrestart/conf.d/50-fluent-package.conf.
In this release, the bundled fluent-plugin-systemd was updated to 1.1.0. That release fixed SIGABORT error with inconsistency of memory allocator handling.
The zero-downtime restart feature can be configured by FLUENT_PACKAGE_SERVICE_RESTART environment variable.
Please refer to following section for more details.
FLUENT_PACKAGE_SERVICE_RESTART environmental variable
FLUENT_PACKAGE_SERVICE_RESTART environment variable.FLUENT_PACKAGE_SERVICE_RESTART environmental variableWe have introduced FLUENT_PACKAGE_SERVICE_RESTART environment variable to configure the zero-downtime restart feature.
The variable exists in the following file:
/etc/sysconfig/fluentd/etc/default/fluentdExample:
FLUENT_PACKAGE_OPTIONS=""
# Control method to upgrade service (auto/manual) restart
FLUENT_PACKAGE_SERVICE_RESTART=auto
The service automatically restarts with zero-downtime restart feature when all of the following conditions are met:
The plugins will be automatically reinstalled if needed if your environment has an active online connection. For more details, please refer to "Automate Plugin Install for Update on Demand".
You can use this approach if you prefer to manage plugins manually or if your environment does not have online connection. If the service was active before the update, it will not restart automatically with this configuration. You need to restart the service manually.
SIGUSR2 signal to the supervisor process, such as with kill -USR2 <PID>systemctl restart fluentd.If you prefer to manage plugins automatically, please set FLUENT_PACKAGE_SERVICE_RESTART to auto (default).
When the service restarts automatically using the zero-downtime restart feature, any missing plugins are automatically detected and reinstalled before the restart.
Previously, automatic restarts after updates were not recommended due to potential issues. If you manually install plugins, you need to reinstall them before restarting when the embedded Ruby version is updated.
To address this, this feature enables automatic plugin installation during the restart process. The steps are as follows:
fluent-plugin- prefix.If you prefer to manage plugins manually, please set FLUENT_PACKAGE_SERVICE_RESTART to manual.
This is useful in cases such as:
In this mode, automatic plugin installation and restarts are disabled.
You can manually install plugins and send a SIGUSR2 signal to trigger the zero-downtime restart feature after the update.
If you use a custom unit file, such as /etc/systemd/system/fluentd.service, please remove these 2 lines.
Environment=GEM_HOME=/opt/fluentd/lib/ruby/gems/...
Environment=GEM_PATH=/opt/fluentd/lib/ruby/gems/...
We don't need GEM_HOME and GEM_PATH.
They will be removed after v5.2.0, but if you use a custom unit file, you need to remove them manually.
If these variables are set, the zero-downtime restart feature may not work correctly.
It is because the new process inherits the original environment variables if using this feature.
Please refer to #713 for more details.
Please see the download page.
We plan to ship the next LTS version of fluent-package v5.0.6 on March, 2025. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 was reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
Hi users!
We have released fluent-package v5.0.5. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This is a maintenance release of v5.0.x LTS series. As bundled Ruby was updated to 3.2.6 and Fluentd was updated to 1.16.6. We recommend upgrading to fluent-package v5.0.5!
In this release, focused on updating bundled ones.
GEM_HOME/GEM_PATH in fluentd.batIn the previous versions of msgpack gem, there was a possibility that cause DoS (Denial Of Service) when crafted message was sent to Fluentd.
When that message was sent, it might cause "NoMemoryError" on Fluentd because there is a case that msgpack try to pre-allocate huge amount of memories.
Above behavior was fixed not to pre-allocate over 32k entries (limit pre-allocated amount of memories) in msgpack 1.7.3 and bundled into fluent-package v5.0.5.
GEM_HOME/GEM_PATH in fluentd.batIn the previous versions, fluentd.bat doesn't set GEMHOME/GEMPATH explicitly.
If users set custom GEM_HOME / GEM_PATH environment variables, the
batch file will not work as expected. Therefore, this patch will set
the appropriate values in the batch file.
Above bug was also fixed in fluent-package v5.0.5.
In this release, the bundled fluent-plugin-systemd was updated to 1.1.0. That release fixed SIGABORT error with inconsistency of memory allocator handling.
Please see the download page.
We plan to ship the next LTS version of fluent-package v5.0.6 on March, 2025. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 was reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
Hi users!
We had launched fluent-package v5 series last year, recently shipped v5.0.4 in LTS release channel and
v5.1.0 in normal release channel.
In this blog article, we explains the planned next major updates - v6.0.0.
In short, we will ship fluent-package v6 in Aug, 2025.
We keeps two release channels as follows:
Here is the difference of these channels.
fluent-package v7.0.0, and will be shipped in 2027 (T.B.D.).As for fluent-package v6,
Current releases and future plans:
| Release Version | Release Date | End of life |
|---|---|---|
| v5.0.x (LTS) | Aug, 2023 | Dec, 2025 |
| v6.0.0 (LTS) | Aug, 2025 | Dec, 2027 (T.B.D.) |
| v7.0.0 (LTS) | Aug, 2027 (T.B.D.) | T.B.D. |
Happy logging!
Hi users!
We have released fluent-package v5.1.0. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This release is a new release of v5.1 series. Bundled ruby version was upgraded to 3.2.5 and fluentd v1.17.0 was shipped!
In this release, focused on updating bundled ones.
In LTS version, conservative updating policy is enabled, so updating gem is very limited to bug fix or security fix. In contrast to LTS version, v5.1.0 bundles more recent components because of standard version.
As we already announced in Scheduled support lifecycle announcement about Fluent Package blog article, in normal release channel, we will ship the latest version (v1.17.0) of Fluentd.
So if you want to try using latest version of Fluentd, v5.1.0 is one for you. If you use fluent-package in enterprise services, keep using fluent-package 5.0.x (LTS).
Please see the download page.
We plan to ship the next LTS version of fluent-package v5.0.5 on Oct, 2024. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 was reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
Hi users!
We have released fluent-package v5.0.4. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This is a maintenance release of v5.0.x LTS series. As bundled Ruby was updated to 3.2.4 and a foolproof mechanism was implemented to prevent launching duplicated Fluentd instances, we recommend upgrading to fluent-package v5.0.4!
In this release, a foolproof mechanism was implemented to prevent launching Fluentd wrongly if the service is already running.
As you know, you can check the version of Fluentd with fluentd --version, but there is a case that fluentd -v is executed wrongly to
do it.
When already running Fluentd as a service, fluentd -v launches a duplicated Fluentd instance with the same fluentd configuration.
If you launch duplicated Fluentd instances, it causes the corruption of processing Fluentd buffer.
To prevent such a situation, a foolproof was implemented now.
For example, if Fluentd is running as a service, launching Fluentd causes an error to block it.
Here is the example on Windows:
> fluentd
Error: Can't start duplicate Fluentd instance with the default config.
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 Windows service 'fluentdwinsvc'.
- Specify the config path explicitly by '-c' ('--config').
Even though if you wrongly launch Fluentd to check version with -v (It should be --version to show version), then it causes the following error.
> fluentd -v
Error: Can't start duplicate Fluentd instance with the default config.
To take the version, please use '--version', not '-v' ('--verbose').
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 Windows service 'fluentdwinsvc'.
- Specify the config path explicitly by '-c' ('--config')
Note that this foolproof feature is intended to block launching duplicated Fluentd instance, you can explicitly launch Fluentd by specifying a specific option to pass it even though already Fluentd is running as a service.
On Windows:
-c (--config)--dry-run--reg-winsvc--reg-winsvc-fluentdopt--show-plugin-configOn Linux:
-c (--config)--dry-run--show-plugin-configPlease see the download page.
We plan to ship the next LTS version of fluent-package v5.0.5 on Oct, 2024. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 was reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
Hi users!
We have released fluent-package v5.0.3. fluent-package is a stable distribution package of Fluentd. (successor of td-agent v4)
This is a maintenance release of v5.0.x LTS series. As significant slow starting service and crash issues during startup on Windows were fixed, we recommend upgrading to fluent-package v5.0.3!
%~dp0 correctly.Please see the download page.
We plan to ship next LTS version of fluent-package v5.0.4 on June, 2024. The content of updates are still in T.B.D.
As it was already announced Drop schedule announcement about EOL of Treasure Agent (td-agent) 4, td-agent v4 was reached EOL in Dec, 2023.
After reached EOL, td-agent v4.5.3 on Windows was released because there was a crash bug during startup on Windows. It was backported fix from fluent-package v5 as it is critical in some case. Even though this was a exceptional maintenance release, but there is no change to the fact that we already stopped maintaining td-agent v4.
We strongly recommend migrating from td-agent v4 to fluent-package v5 (LTS). See Upgrade to fluent-package v5
Fluentd is an open source data collector to simplify log management.
2025-09-04: Upgrade Guide for fluent-package v6
2024-08-29: Scheduled support lifecycle announcement about Fluent Package v6
2023-08-29: Drop schedule announcement about EOL of Treasure Agent (td-agent) 4
2023-08-29: Scheduled support lifecycle announcement about Fluent Package
2023-07-31: Upgrade to fluent-package v5
2025-09-12: Fluentd v1.16.10 has been released
2025-09-04: Upgrade Guide for fluent-package v6
2025-08-29: fluent-package v6.0.0 has been released
2025-08-06: Fluentd v1.19.0 has been released
2025-05-16: fluent-package v5.0.7 has been released
2025-05-14: Fluentd v1.16.9 has been released
2025-05-01: Fluentd v1.16.8 has been released
2025-03-14: Drop Alpine and switch default to Debian for Fluentd docker image
2025-02-14: fluent-package v5.0.6 has been released
2025-01-29: Fluentd v1.16.7 has been released
Want to learn the basics of Fluentd? Check out these pages.
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