Fluentd Blog

Upgrade Guide for fluent-package v6

On August 29, 2025, we released fluent-package v6 as a new series of stable packages.

What is Fluent Package v6 LTS?

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:

• fluent-package v6.0.0 has been released

Upgrade procedure to Fluent Package v6 LTS

As an example, you can upgrade with the following steps:

1. Check manually installed plugins
2. Stop the Fluentd service
3. Back up registry settings (Windows only)
4. Install Fluent Package v6 LTS
5. Reinstall plugins
6. Restart the Fluentd service

Below are details for each step.

1. Check manually installed plugins

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.output

For 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If you are using a version earlier than v5.0.2, the bundled fluent-diagtool is outdated.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.

2. Stop the Fluentd service

Stop any running Fluentd service(s). If multiple Fluentd services are running, stop them in the order: forwarders first, then aggregators.

3. Back up registry settings (Windows only)

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

4. Install Fluent Package v6 LTS

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:

• RPM Package (Red Hat Linux)
• DEB Package (Debian/Ubuntu)
• .msi Installer (Windows)

5. Reinstall plugins

The manually installed plugins need to be reinstalled. Reinstall the plugins identified in step 1.

Example:

$ sudo fluent-gem install fluent-plugin-remote_syslog

6. Restart the Fluentd service

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:

• auto (default): automatically performs zero-downtime restart after update
• manual: requires manual zero-downtime restart, disabling automatic plugin reinstallation and restart

This setting can be changed anytime and does not require restarting Fluentd itself.

For details, see:

• fluent-package v5.2.0 has been released

Rollback from Fluent Package v6 LTS to v5

1. Stop the Fluentd service

Stop running Fluentd services, in the order from forwarders to aggregators.

2. Install Fluent Package v5 LTS

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.

3. Restore the registry (Windows only)

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.

4. Restart the Fluentd service

Restart the stopped Fluentd services in opposite order: aggregators first, then forwarders.

Download

Please see the download page.

Announcement

End of support for td-agent v4, let's migrate to fluent-package

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.

Follow us on X

We have been posting information about Fluentd in Japanese on @fluentd_jp. We would appreciate it if you followed our X account.

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Scheduled support lifecycle announcement about Fluent Package v6

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.

When the next LTS (Long Term Support) version available?

In short, we will ship fluent-package v6 in Aug, 2025.

We keeps two release channels as follows:

• Normal release
• LTS (Long Term Support)

Here is the difference of these channels.

• Normal release (6.x series)
  • Recommended for early adopters (eager to try new features of Fluentd)
  • Rapid release development (planned semi-annually releases, but it may vary.)
  • Fluentd will be upgraded occasionally
    • Minor upgrade will be applied. e.g. 1.18 => 1.19 and so on.
    • e.g. v6.0.1 (Fluentd v1.18.1), v6.0.2 (Fluentd v1.18.2), ... v6.1.0 (Fluentd v1.19.0)
  • The only latest version will be supported (bug fix will not be backported into older version)
• LTS (Long Term Support, 6.0.x series)
  • Recommended for enterprise services
  • Security and bug fix release only
  • Fluentd will be upgraded only in the teeny version and will stick to 1.18.x series. (T.B.D.)
    • Thus, the version number will be 6.0.x. (6.1 series will not be shipped for LTS channel)
    • e.g. v6.0.1 (Fluentd v1.18.1), v6.0.2 (Fluentd v1.18.2), v6.0.3 (Fluentd v1.18.3) ... v6.0.x (Fluentd v1.18.x) and so on.
  • Next major version will be fluent-package v7.0.0, and will be shipped in 2027 (T.B.D.).

As for fluent-package v6,

• fluent-package v5 LTS will be supported until Dec, 2025.
  • We expect users upgrade from v5 to v6 during the grace period.
• Until 6.1.0 is released, normal release channel and LTS channel are the same package.
• Upgrade from v4 or older version is not supported. Upgrade to v5 first, then upgrade it to v6.

Current releases and future plans:

Happy logging!

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Drop schedule announcement about EOL of Treasure Agent (td-agent) 4

Hi users and developers!

We announce the dropping schedule for TD Agent 4 development.

About Treasure Agent (td-agent) 4

Since td-agent 4.0.0 was released in 2020, td-agent 4 has been maintained for a long time.

As new major version of td-agent 4 was rebranded (to fluent-package v5), and released in August 2023, we decided to stop maintaining td-agent 4.

Scheduled end of life - Dec 2023

As you know, already stepping down maintenance activity, new minor update for td-agent 4 will not be shipped anymore. (td-agent v4.5.1 will be the last release of this series, it will be shipped in this month.)

Thus, we recommend using fluent-package v5 for new deployment :)

How to migrate to Fluent Package v5

There is a good article to do it.

• Upgrade to fluent-package v5

Follow the above instructions.

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Scheduled support lifecycle announcement about Fluent Package

Hi users!

We have released fluent-package v5.0.0 (Release Candidate) and the following v5.0.1 (General Availability). fluent-package is formerly known as td-agent and a stable distribution package of Fluentd.

In this blog article, we explains why the concept of channels is introduced.

Why is LTS (Long Term Support) channel introduced?

In the previous versions, td-agent was shipped as quarterly releases in most cases. It sometimes contains fluentd minor upgrade occasionally, which means that not only bug or security fixes, but also contains new features. As a result, there was a case that the stability was affected unexpectedly.

In point view of adopting fluentd (and td-agent) for enterprise services, there was a requirement for the distribution which contains security or bug fixes only and scheduled lifecycle of it.

The LTS release is the answer to support them.

Channels for updates

There are two channels of support lifecycle.

• Normal release
• LTS (Long Term Support)

Here is the difference of these channels.

• Normal release (5.x series)
  • Recommended for early adopters (eager to try new features of Fluentd)
  • Rapid release development (planned semi-annually releases, but it may vary.)
  • Fluentd will be upgraded occasionally
    • Minor upgrade will be applied. e.g. 1.16 => 1.17 and so on.
    • e.g. v5.0.1 (Fluentd v1.16.2), v5.0.2 (Fluentd v1.16.3), ... v5.1.0 (Fluentd v1.17.0)
  • The only latest version will be supported (bug fix will not be backported into older version)
• LTS (Long Term Support, 5.0.x series)
  • Recommended for enterprise services
  • Security and bug fix release only
  • Fluentd will be upgraded only in the teeny version and will stick to 1.16.x series.
    • Thus, the version number will be 5.0.x. (5.1 series will not be shipped)
    • e.g. v5.0.1 (Fluentd v1.16.2), v5.0.2 (Fluentd v1.16.3), v5.0.3 (Fluentd v1.16.4) ... v5.0.x (Fluentd v1.16.x)
  • Next major version will be fluent-package v6.0.0, and will be shipped in 2025.

As for fluent-package v5,

• fluent-package v5 LTS will be supported until Dec, 2025 (Even though Ruby 3.2 is still supported)
• Until 5.1.0 is released, normal release channel and LTS channel are the same package.

* td-agent v4, including v4.5.2 and v4.5.3, has reached End of life at the end of December 2023.

Happy logging!

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Upgrade to fluent-package v5

fluent-package "v5" is available since August 2023. fluent-package is the successor of td-agent "v4".

In this post, we will share the steps we've tested and hopefully this will help your experience from v4 to v5.

Why package was renamed?

fluent-package was formerly known as td-agent. In the past, Treasure Data, Inc took the initiative to provide the package, but now the Fluentd community does it. This is why the package name was changed.

To represent "All in one package of Fluentd which contains Fluentd and related gem packages", the package name was changed to fluent-package.

Even though package name was changed, Treasure Data, Inc still sponsor the package delivery resources.

Which channel should I use?

There are two channels for fluent-package.

• Normal release version
• Long Term Support version

One is normal release version which will be updated regularly - rapid release development style (td-agent v4 was released like this in almost every quarter). In this version, fluentd will be eventually updated to newer minor version (e.g. 1.17.x and so on)

The other is a more conservative maintenance version (Long Term Support) which will not introduce a new feature. It only applies teeny update such as security or bug fix only. LTS for v5 will be supported until March, 2025.

More details about difference between normal release version and LTS version will be explained in Scheduled support lifecycle announcement about Fluent Package.

Differences between td-agent v4 and fluent-package v5

In the fluent-package v5, core components like ruby (2.7.8 -> 3.2.2) and OpenSSL (1.1.1 -> 3.1.0 for Windows, 3.0.8 for macOS) were updated.

The major changes are as follows.

• td-agent command is renamed to fluentd.
  • $ td-agent --version -> $ fluentd --version
• td-agent-gem command is renamed to fluent-gem.
  • $ td-agent-gem list -> $ fluent-gem list
• The service name for non-Windows td-agent is renamed to fluentd.
  • $ systemctl status td-agent -> $ systemctl status fluentd

With the change of package name, install path, service name (e.g. /opt/fluent, fluentd.service) and so on were also changed. Basically, for td-agent v4 users, it aims to keep compatibility as far as possible by executing the migration process with copying old files or providing symbolic links for it.

If you want to know the details of upgraded components, see CHANGELOG.md.

NOTE: We explain for platform specific issue as "Additional hints for v4 users" section below.

Upgrade steps

During the upgrade process, plugins bundled in td-agent are automatically upgraded. With that being said, other plugins added on your own are not included. You should review if you need to upgrade plugins since some directory structures from v4 and v5 are changed.

In this post, I will show steps with plugins added on my own, "fluent-plugin-concat" for instance. Here is sample configuration file I used through steps.

<filter docker.log>
  @type concat
  key message
  multiline_start_regexp /^Start/
</filter>

1. Review what plugins are installed together with td-agent v4.

$ td-agent-gem list | grep fluent-plugin*
fluent-plugin-calyptia-monitoring (0.1.3)
fluent-plugin-concat (2.5.0)
fluent-plugin-elasticsearch (5.3.0)
fluent-plugin-flowcounter-simple (0.1.0)
fluent-plugin-kafka (0.19.0)
fluent-plugin-metrics-cmetrics (0.1.2)
fluent-plugin-opensearch (1.1.0)
fluent-plugin-prometheus (2.0.3)
fluent-plugin-prometheus_pushgateway (0.1.0)
fluent-plugin-record-modifier (2.1.1)
fluent-plugin-rewrite-tag-filter (2.4.0)
fluent-plugin-s3 (1.7.2)
fluent-plugin-sd-dns (0.1.0)
fluent-plugin-systemd (1.0.5)
fluent-plugin-td (1.2.0)
fluent-plugin-utmpx (0.5.0)
fluent-plugin-webhdfs (1.5.0)

You can also find installed plugins under /opt/td-agent/lib/ruby/gems/2.7.0/gems/ directories.

$ ls -l /opt/td-agent/lib/ruby/gems/2.7.0/gems |grep fluent-plugin*
drwxr-xr-x. 5 root root  175  7月 14 03:01 fluent-plugin-calyptia-monitoring-0.1.3
drwxr-xr-x. 4 root root  206  7月 14 03:03 fluent-plugin-concat-2.5.0
drwxr-xr-x. 5 root root 4096  7月 14 03:01 fluent-plugin-elasticsearch-5.3.0
drwxr-xr-x. 4 root root  205  7月 14 03:01 fluent-plugin-flowcounter-simple-0.1.0
drwxr-xr-x. 6 root root  191  7月 14 03:01 fluent-plugin-kafka-0.19.0
drwxr-xr-x. 5 root root  190  7月 14 03:01 fluent-plugin-metrics-cmetrics-0.1.2
drwxr-xr-x. 5 root root 4096  7月 14 03:01 fluent-plugin-opensearch-1.1.0
drwxr-xr-x. 5 root root  215  7月 14 03:01 fluent-plugin-prometheus-2.0.3
drwxr-xr-x. 6 root root  238  7月 14 03:01 fluent-plugin-prometheus_pushgateway-0.1.0
drwxr-xr-x. 4 root root  176  7月 14 03:01 fluent-plugin-record-modifier-2.1.1
drwxr-xr-x. 3 root root  210  7月 14 03:01 fluent-plugin-rewrite-tag-filter-2.4.0
drwxr-xr-x. 5 root root  230  7月 14 03:01 fluent-plugin-s3-1.7.2
drwxr-xr-x. 3 root root  170  7月 14 03:01 fluent-plugin-sd-dns-0.1.0
drwxr-xr-x. 3 root root   49  7月 14 03:01 fluent-plugin-systemd-1.0.5
drwxr-xr-x. 5 root root  221  7月 14 03:01 fluent-plugin-td-1.2.0
drwxr-xr-x. 5 root root  166  7月 14 03:01 fluent-plugin-utmpx-0.5.0
drwxr-xr-x. 4 root root  191  7月 14 03:01 fluent-plugin-webhdfs-1.5.0

2. Stop td-agent v4 daemon.

$ sudo systemctl stop td-agent

Even though fluent-package supports upgrade without stopping service, but recommend to stop explicitly.

3. Run installation script of fluent-package v5.

When you use RedHat or derivative distributions, you can run following script if you want to install normal release version of fluent-package.

# curl -L https://toolbelt.treasuredata.com/sh/install-redhat-fluent-package5.sh | sh

When you use RedHat or derivative distributions, you can run following script if you want to install LTS (Long term support) version of fluent-package.

# curl -L https://toolbelt.treasuredata.com/sh/install-redhat-fluent-package5-lts.sh | sh

You can find more information about the installation script in Fluend Doc - Installation.

4. Confirm if fluent-package v5 is properly installed.

$ LANG=C yum info fluent-package
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: ftp.riken.jp
 * extras: ftp.riken.jp
 * updates: ftp.riken.jp
Installed Packages
Name        : fluent-package
Arch        : x86_64
Version     : 5.0.0
Release     : 1.el7
Size        : 64 M
Repo        : installed
From repo   : /fluent-package-5.0.0-1.el7.x86_64
Summary     : The stable distribution of Fluentd
URL         : https://www.treasuredata.com/
License     : ASL 2.0
Description : The stable distribution of Fluentd, called td-agent.

5. Reload fluent-package daemon.

$ sudo systemctl daemon-reload
$ sudo systemctl enable --now fluentd

6. Check installed plugins.

$ fluent-gem list |grep fluent-plugin*
fluent-plugin-calyptia-monitoring (0.1.3)
fluent-plugin-elasticsearch (5.3.0)
fluent-plugin-flowcounter-simple (0.1.0)
fluent-plugin-kafka (0.19.0)
fluent-plugin-metrics-cmetrics (0.1.2)
fluent-plugin-opensearch (1.1.0)
fluent-plugin-prometheus (2.0.3)
fluent-plugin-prometheus_pushgateway (0.1.0)
fluent-plugin-record-modifier (2.1.1)
fluent-plugin-rewrite-tag-filter (2.4.0)
fluent-plugin-s3 (1.7.2)
fluent-plugin-sd-dns (0.1.0)
fluent-plugin-systemd (1.0.5)
fluent-plugin-td (1.2.0)
fluent-plugin-utmpx (0.5.0)
fluent-plugin-webhdfs (1.5.0)

You can see bundled plugins are upgraded as well but can not find plugins added on your own. In this post, added plugin was "fluent-plugin-concat" and it is not shown in installed list.

7. Install plugins added on my own.

$ sudo fluent-gem install fluent-plugin-concat

$ fluent-gem list | grep fluent-plugin*
fluent-plugin-calyptia-monitoring (0.1.3)
fluent-plugin-concat (2.5.0)
fluent-plugin-elasticsearch (5.3.0)
fluent-plugin-flowcounter-simple (0.1.0)
fluent-plugin-kafka (0.19.0)
fluent-plugin-metrics-cmetrics (0.1.2)
fluent-plugin-opensearch (1.1.0)
fluent-plugin-prometheus (2.0.3)
fluent-plugin-prometheus_pushgateway (0.1.0)
fluent-plugin-record-modifier (2.1.1)
fluent-plugin-rewrite-tag-filter (2.4.0)
fluent-plugin-s3 (1.7.2)
fluent-plugin-sd-dns (0.1.0)
fluent-plugin-systemd (1.0.5)
fluent-plugin-td (1.2.0)
fluent-plugin-utmpx (0.5.0)
fluent-plugin-webhdfs (1.5.0)

As for fluent-package v5, "fluent-plugin-concat" was installed under "/opt/fluent/lib/ruby/gems/3.2.0/gems/" directories.

$ ls -l /opt/fluent/lib/ruby/gems/3.2.0/gems/ |grep fluent-plugin*
drwxr-xr-x.  5 root root  175  7月 14 03:14 fluent-plugin-calyptia-monitoring-0.1.3
drwxr-xr-x.  4 root root  206  7月 14 03:16 fluent-plugin-concat-2.5.0
drwxr-xr-x.  5 root root 4096  7月 14 03:14 fluent-plugin-elasticsearch-5.3.0
drwxr-xr-x.  4 root root  205  7月 14 03:14 fluent-plugin-flowcounter-simple-0.1.0
drwxr-xr-x.  6 root root  191  7月 14 03:14 fluent-plugin-kafka-0.19.0
drwxr-xr-x.  5 root root  190  7月 14 03:14 fluent-plugin-metrics-cmetrics-0.1.2
drwxr-xr-x.  5 root root 4096  7月 14 03:14 fluent-plugin-opensearch-1.1.0
drwxr-xr-x.  5 root root  215  7月 14 03:14 fluent-plugin-prometheus-2.0.3
drwxr-xr-x.  6 root root  238  7月 14 03:14 fluent-plugin-prometheus_pushgateway-0.1.0
drwxr-xr-x.  4 root root  176  7月 14 03:14 fluent-plugin-record-modifier-2.1.1
drwxr-xr-x.  3 root root  210  7月 14 03:14 fluent-plugin-rewrite-tag-filter-2.4.0
drwxr-xr-x.  5 root root  230  7月 14 03:14 fluent-plugin-s3-1.7.2
drwxr-xr-x.  3 root root  170  7月 14 03:14 fluent-plugin-sd-dns-0.1.0
drwxr-xr-x.  3 root root   49  7月 14 03:14 fluent-plugin-systemd-1.0.5
drwxr-xr-x.  5 root root  221  7月 14 03:14 fluent-plugin-td-1.2.0
drwxr-xr-x.  5 root root  166  7月 14 03:14 fluent-plugin-utmpx-0.5.0
drwxr-xr-x.  4 root root  191  7月 14 03:14 fluent-plugin-webhdfs-1.5.0

8. Start fluent-package v5 daemon.

$ sudo systemctl start fluentd

9. Check if there are no error messages in fluentd logs.

$ tail -100f /var/log/fluent/fluentd.log

Now, upgrading steps are completed. Happy Logging!

Additional hints for v4 users

For Debian/Ubuntu

• fluentd-apt-source package will be marked as a transitional package. you can remove it safely with sudo apt purge fluentd-apt-source.
• If you want to enable td-agent.service, you must explicitly execute the following commands:

  $ sudo systemctl unmask td-agent
  $ sudo systemctl enable fluentd

For RHEL

• If you want to enable td-agent.service, you must explicitly execute the following command:

  $ sudo systemctl enable fluentd

For Windows

• fluent-package installer was changed not to start service by default. If you want to start fluentd as a service, execute the following command with administrator privileges.

  c:\opt\fluent> net start fluentdwinsvc

For macOS

WARNING: Currently we have no plan to officially support dmg version of fluent-package yet. It is just modified to be a minimally buildable state, it is for testing purpose only.

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