Hi users!
We have released fluent-package v6.0.3 on 2026-03-27. Fluent Package is a stable distribution package of Fluentd. (successor of td-agent)
This is a maintenance release of v6.0.x LTS series.
Fluent Package v6.0.3 includes the following improvements:
cool.io v1.9.3 under specific conditionsThis article explains the changes in Fluent Package v6.0.3.
In fluent-package v6.0.2, a critical issue was discovered where memory usage continuously increases over time. This release completely resolves this problem.
out_forward plugin with the keepalive false setting (which is the default value).cool.io (v1.9.2 and v1.9.3) bundled in fluent-package v6.0.2 had a bug in its detachment process.cool.io v1.9.4 which fixes this bug, and it is now bundled by default in fluent-package v6.0.3. If operated for a long period, this memory leak will exhaust system memory resources, eventually causing the Fluentd process to be terminated unexpectedly by the OOM (Out of Memory) Killer. We strongly recommend users who are using out_forward on v6.0.2 to update to this version immediately.
Note: Users on fluent-package v6.0.1 or earlier are not affected by this specific issue.
Ruby 3.4.9 includes multiple bug and security fixes. Specifically, it addresses the following vulnerability:
For details, please see the Ruby 3.4.9 release notes.
We have updated the bundled Nokogiri from v1.18.10 to v1.19.2 for the Windows version to address the following vulnerability:
Please visit the download page.
We plan to release the next LTS version of fluent-package v6.0.4 at June 2026. The content of updates are still TBD.
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 v6.0.2 on 2026-02-27. Fluent Package is a stable distribution package of Fluentd. (successor of td-agent)
This is a maintenance release of v6.0.x LTS series.
Fluent Package v6.0.2 includes the following improvements:
This article explains the changes in Fluent Package v6.0.2.
Ruby 3.4.8 includes multiple bug and security fixes. For details, please see the Ruby 3.4.8 release notes.
Fluentd v1.19.2 includes the following fixes:
config_include_dirFor details, please see the Fluentd v1.19.2 has been released.
In this release, it was fixed update error if temporary working directory was removed.
In the previous versions, if temporary working directory was removed by tmpfiles.d, there was a case that updating to v6 (up to v6.0.1) causes fatal error while rpm processes transaction.
Now, with changing temporary working directory handling, it was fixed in v6.0.2.
Since v6.0.0, installation maintenance script (powershell) was partially introduced for Windows. But in some environments, there is a case that the execution of powershell was prohibited in your policy. In such a case, installation process will be failed unexpectedly.
In this release, added fallback not to terminate installation process accidentally.
Please visit the download page.
We plan to release the next LTS version of fluent-package v6.0.3 at June 2026. The content of updates are still TBD.
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 v1.19.2 on 2026-02-13. ChangeLog is here.
This release is a maintenance release of v1.19 series.
This release will be bundled for upcoming fluent-package LTS version v6.0.2!
config_include_dirSince Fluentd v1.19.0, the configuration files under/etc/fluent/conf.d were
changed to load automatically.
This feature was introduced to load builtin plugins and designed to work well with fluent-package.
But, as a side effect, there is a case that duplicated configuration files are
loaded if user already configured to include from /etc/fluent/conf.d.
In that case, it causes startup failures. Thus, user need to disable with config_include_dir "" explicitly as a workaround.
In this release, not to raise startup failure, we fixed duplicate configured file loading in config_include_dir.
in_tail: fixed error when files without read permission are included in glob patternsIn the previous versions, if you enabled Linux capability feature with Fluentd, there is a case that it causes an error.
It was caused when accessing uninitialized instance variable.
out_forward: added timeout to prevent infinite loop under unstable network connectionIn unstable network environments with proxy components, if connection drops during handshake after TLS establishment, Fluentd gets stuck in infinite loop causing logs to stop being flushed.
In this release, fixed to uses existing hard_timeout configuration to break the loop,
then disable problematic nodes, and maintain log flow through healthy nodes.
This fixes improves stability of Fluentd.
net-http gem had a bug in handling IPv6 addresses, and updating the uri gem
would trigger strict checking, thus causing errors.
It was affected when you installed via gem command.
There is a case that unintentionally backed-up conf file will be loaded by wild card @include.
It will help to detect such a careless mistakes by warning.
For example, if you include configuration file by @include conf/*.conf, and there are
unintentionally backed-up file exists (conf/dummy.bak.conf), usually it causes startup failures.
In this release, it detects such a case as a warning.
$ fluentd -c wildcard_include.conf --dry-run
2026-02-12 17:41:39 +0900 [info]: init supervisor logger path=nil rotate_age=nil rotate_size=nil
2026-02-12 17:41:39 +0900 [warn]: There is a possibility that '@include conf/*.conf' includes duplicated backed-up config file such as <dummy.bak.conf>
2026-02-12 17:41:39 +0900 [info]: parsing config file is succeeded path="wildcard_include.conf"
2026-02-12 17:41:39 +0900 [info]: configuration include directory is disabled
2026-02-12 17:41:39 +0900 [info]: gem 'fluentd' version '1.19.0'
2026-02-12 17:41:39 +0900 [info]: starting fluentd-1.19.0 as dry run mode ruby="3.4.8"
2026-02-12 17:41:39 +0900 [info]: using configuration file: <ROOT>
<system>
config_include_dir ""
</system>
<source>
@type forward
</source>
<source>
@type forward
</source>
</ROOT>
2026-02-12 17:41:39 +0900 [info]: finished dry run mode
Enjoy logging!
We have been posting information about Fluentd in Japanese on @fluentd_jp. We would appreciate it if you followed the X account.
Hi users and developers!
As already planned before, we announce the dropping schedule for Fluent Package 5 (LTS) development.
Since fluent-package 5.0.0 was released in 2023, fluent-package 5 has been maintained for a long time.
As new major version of fluent-package 6 was released in August 2025, we decided to stop maintaining fluent-package 5 in Dec 31, 2025.
LTS version of fluent-package v6 will be planned support until Dec, 2027. It will meet for your enterprise services.
As you know, already stepping down maintenance activity, new minor update for fluent-package 5 will not be shipped anymore. fluent-package v5.0.9 should be the last release of this series, it was shipped in Dec 19, 2025.
Thus, we recommend using fluent-package v6 for new deployment :)
There is a good article to do it.
Follow the above instructions.
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 v5.0.9 on December 19, 2025. 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.
Fluent Package v5 LTS series is scheduled to be supported until the end of 2025. This release (v5.0.9) is planned to be the final version of the v5 LTS series.
Please refer to Scheduled support lifecycle announcement about Fluent Package v6.
This article explains the changes in Fluent Package v5.0.9.
Fluentd v1.16.11 includes the following fixes:
<security> and TLS setting together under unstable network environments
Please see the download page.
This release (v5.0.9) is planned to be the final version of the v5 LTS series. We strongly recommend upgrading to Fluent Package v6 LTS series for next long term support.
Please refer to Scheduled support lifecycle announcement about Fluent Package v6.
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 v1.16.11 on 2025-12-09. ChangeLog is here.
This release is expected to be the final release of v1.16 series.
This release will be bundled for upcoming fluent-package LTS version v5.0.9!
<security> and TLS setting together under unstable network environmentsThis issue occurs when using out_forward with TLS enabled in unstable network environments.
If the communication is lost during the connection process immediately after TLS is established,
the out_forward connection process could fall into an infinite loop.
As a result, the log output stops completely.
To address this, we have updated the plugin to apply the existing hard_timeout parameter to this connection phase. This introduces a mechanism to interrupt the stuck process via timeout and allow it to recover.
Enjoy logging!
This release (v1.16.11) is planned to be the final version of the v1.16 series. We strongly recommend upgrading to Fluentd v1.19 series for next long term support.
Please refer to Scheduled support lifecycle announcement about Fluent Package v6.
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 v6.0.1 on 2025-11-11. Fluent Package is a stable distribution package of Fluentd. (successor of td-agent v4)
This is a maintenance release of v6.0.x LTS series.
Fluent Package v6.0.1 includes the following improvements:
This article explains the changes in Fluent Package v6.0.1.
Ruby 3.4.7 includes multiple bug and security fixes. For details, please see the Ruby 3.4.7 release notes.
Fluentd v1.19.1 includes the following fixes:
Previously, when specifying multiple values, you had to use a comma-separated list such as: retryable_response_codes: 503, 504.
With this update, you can now use more YAML-style array notations:
retryable_response_codes: [503, 504]
or
retryable_response_codes:
- 503
- 504
Note: The special element $arg has supported array notation from earlier versions.
Note: There is still a known YAML syntax issue where specifying a single int value for an Array option causes a config error. For details, please refer to #5149.
This issue, which was previously fixed in Fluent Package v5.0.8, has now been included in Fluent Package v6.0.1.
On some Linux distributions, tmpfiles.d is configured as follows, and files or directories in /tmp that remain unused for more than 10 days are deleted:
q /tmp 1777 root root 10d
When using the out_file or out_secondary_file plugins, Fluentd uses temporary directory like /tmp/fluentd-lock-{...}/, depending on the config.
If there is no output with out_file or out_secondary_file for an extended period, the temporary directory could be deleted by tmpfiles.d.
If the temporary directory is deleted while Fluentd is running, the following error occurs continuously in out_file and out_secondary_file output:
2025-09-11 14:33:29 +0900 [warn]: #2 failed to flush the buffer. retry_times=0 next_retry_time=2025-09-11 14:33:30 +0900 chunk="63e7fdca888e679a6fcdefb0c120bf58" error_class=Errno::ENOENT error="No such file or directory @ rb_sysopen - /tmp/fluentd-lock-20250911-1545462-74fvkh/fluentd-foo.lock"
Normally, some output is written periodically, so this issue is rare. If it occurs, you can restore normal operation by restarting Fluentd before reaching the retry limit.
In this release, we added a rule to /usr/lib/tmpfiles.d/fluentd.conf to exclude /tmp/fluentd-lock-{...}/ from automatic deletion.
This fixes an issue in the Windows installer of Fluent Package v6.0.0.
When installing Fluent Package to a path containing spaces (e.g., C:\Program Files\fluentd), an error could occur during installation.
This issue has been fixed in v6.0.1.
Please visit the download page.
We plan to release the next LTS version of fluent-package v6.0.2 at February 2026. The content of updates are still TBD.
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 v1.19.1 on 2025-11-06. ChangeLog is here.
This release is a maintenance release of v1.19 series.
This release will be bundled for upcoming fluent-package LTS version v6.0.1!
Previously, when specifying multiple values, you had to use a comma-separated list such as: retryable_response_codes: 503, 504.
With this update, you can now use more YAML-style array notations:
retryable_response_codes: [503, 504]
or
retryable_response_codes:
- 503
- 504
Note: The special element $arg has supported array notation from earlier versions.
Note: There is still a known YAML syntax issue where specifying a single int value for an Array option causes a config error. For details, please refer to #5149.
Enjoy logging!
Hi users!
We have released fluent-package v5.0.8 on October 8, 2025. 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 1.16.10.
This article explains the changes in Fluent Package v5.0.8.
Ruby 3.2.9 includes multiple security and bug fixes. For details, please see the Ruby 3.2.9 release notes.
Fluentd v1.16.10 includes the following fixes:
On some Linux distributions, tmpfiles.d is configured as follows, and files or directories in /tmp that remain unused for more than 10 days are deleted:
q /tmp 1777 root root 10d
When using the out_file or out_secondary_file plugins, Fluentd uses temporary directory like /tmp/fluentd-lock-{...}/, depending on the config.
If there is no output with out_file or out_secondary_file for an extended period, the temporary directory could be deleted by tmpfiles.d.
If the temporary directory is deleted while Fluentd is running, the following error occurs continuously in out_file and out_secondary_file output:
2025-09-11 14:33:29 +0900 [warn]: #2 failed to flush the buffer. retry_times=0 next_retry_time=2025-09-11 14:33:30 +0900 chunk="63e7fdca888e679a6fcdefb0c120bf58" error_class=Errno::ENOENT error="No such file or directory @ rb_sysopen - /tmp/fluentd-lock-20250911-1545462-74fvkh/fluentd-foo.lock"
Normally, some output is written periodically, so this issue is rare. If it occurs, you can restore normal operation by restarting Fluentd before reaching the retry limit.
In this release, we added a rule to /usr/lib/tmpfiles.d/fluentd.conf to exclude /tmp/fluentd-lock-{...}/ from automatic deletion.
The bundled Nokogiri (for Windows only) has been updated from v1.16.8 to v1.18.10 to address the following vulnerabilities:
The bundled rexml has been updated from v3.3.9 to v3.4.4 to address the following vulnerabilities:
Please see the download page.
We plan to release the next LTS version of fluent-package v5.0.9 by the end of 2025. The content of updates are still TBD.
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 the X account.
Hi users!
We have released v1.16.10 on 2025-09-12. ChangeLog is here.
This release is a maintenance release of v1.16 series.
This release will be bundled for upcoming fluent-package LTS version v5.0.8!
This issue has existed since this helper was first introduced and has affected at least Fluentd v0.14 and td-agent v3 and later.
The official plugins mainly affected are:
This bug causes the following two problems:
Fluentd normally shuts down each plugin in a safe sequence, but this bug causes it to continue receiving data unexpectedly during a phase when new data should no longer be accepted.
Even if buffer files remain, they will be restored on the next start, so this is not an issue. On the other hand, when using a memory buffer, the risk of log loss becomes much higher.
Please note that this bug is unlikely to be a major problem when using a file buffer. In the first place, server-type input plugins generally cannot receive data while Fluentd is down, so unless the client has a resend mechanism, there is always a risk of log loss during Fluentd's restart. With the zero-downtime restart feature introduced in Fluentd v1.18 (fluent-package v5.2 or v6), Fluentd can now be restarted without downtime.
Ref: Fluentd#5026
Enjoy logging!
Fluentd is an open source data collector to simplify log management.
2025-12-25: Drop schedule announcement about EOL of Fluent Package (fluent-package) 5
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
2026-03-27: fluent-package v6.0.3 has been released
2026-02-27: fluent-package v6.0.2 has been released
2026-02-13: Fluentd v1.19.2 has been released
2025-12-25: Drop schedule announcement about EOL of Fluent Package (fluent-package) 5
2025-12-19: fluent-package v5.0.9 has been released
2025-12-09: Fluentd v1.16.11 has been released
2025-11-11: fluent-package v6.0.1 has been released
2025-11-06: Fluentd v1.19.1 has been released
2025-10-08: fluent-package v5.0.8 has been released
2025-09-12: Fluentd v1.16.10 has been released
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