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The Official Blog of Mackerel

(Appended)【Urgent Maintenance】The system will temporarily shut down for database maintenance on Feb. 2 (Thur) at 2:30 pm

Thank you for choosing Mackerel.

【Added content】

Regarding the scheduled maintenance, the problem is being resolved and the maintenance has been cancelled. For more details, refer to the following entry.

【End of added content】

The system will be temporarily suspended for maintenance according to the schedule below. We apologize for any inconvenience that this may cause and appreciate your understanding.

Moreover, we apologize for such a short notice due to the urgency of this maintenance.

Scheduled date and time

  • February 7th (Thur) 2:30 pm - 4:30 pm (JST)
    • This time window is the longest case scenario. A breakdown of the procedure of operations will follow below.


  • Database maintenance

Regarding impact on the day of

  • The above time window is an estimate of the longest case scenario. The actual maintenance period will end once the work has been completed.
    • Once maintenance has begun, the entire Mackerel system will shutdown for a short period of time.
  • Web access to Mackerel, data posting by the agent, API access (including the CLI tool), alert notifications, etc. will be unavailable
  • As soon as the maintenance work is completed and operation is confirmed, the system shutdown will end and an announcement will be made
  • As for mackerel-agent metric posting, data will be buffered from mackerel-agent during the maintenance period and resent after maintenance has been completed
    • If resent properly, graphs during the maintenance period will also be displayed.

Reason for maintenance

In PostgreSQL (RDS), a data store used by Mackerel, autovacuum isn’t running properly. In the current state, service operations have not been affected, but if this state continues, the transaction ID will be exhausted and the update function for the database will be forcibly stopped. For this reason, we’ve decided that urgent maintenance is necessary.

Related to this, a similar Bug Report ( ) was submitted and found that the problem can be restored by rebooting.

We will try this during the maintenance period. In addition, as a result of preliminary inspection, we’ve confirmed that autovacuum can be run on DB restored from snapshot. And if the problem can’t be resolved by rebooting, that will be the next issue addressed.

Procedure of operations

  • Temporary system shutdown
  • RDS reboot
    • If recovery is confirmed here, maintenance will end
  • Replace with DB restored from snapshot
  • After recovery is confirmed, maintenance will end

The 2 hour maintenance time window is an estimation of recovery time based on the snapshot. If the issue is resolved by rebooting, maintenance will end at that point.

Regarding Announcements

Situation reports will be made from the Mackerel status page ( as well as from this blog (

Additionally, we’ll also be using our official Twitter account (

For inquiries related to this matter

Please send all inquiries regarding this matter to

Thank you again for your understanding and cooperation. And thank you for choosing Mackerel.

AWS Integration now supported with Elasticsearch Service and more

Mackerel team CRE Miura (id:missasan) here.

The first event for the Kansai branch of the Mackerel UG is going to be held at the Osaka office of Aiming Inc.! The Mackerel team is planning to mix and mingle at the event so if your in the Kansai area, please join us!

Now on to this week’s update information.

AWS Integration now supported with Elasticsearch Service

Check out the following help page for the details.

Aurora Serverless clusters can now be integrated with AWS Integration RDS

Managing database instances is unnecessary in Aurora Serverless. With Aurora Serverless enabled with AWS Integration, clusters are counted as one host.

Obtainable metrics have been added as well. Check out more of the details in the help page linked below.

Mackerel UG Kansai Meetup #1!

Several presentations are planned for this event. Itec Hankyu Hanshin will be presenting on "Introducing Mackerel in fully managed hosting", the same as there presentation at Mackerel Meetup # 12 in Tokyo. And Beyond Co., Ltd. will be talking about "Comparing server monitoring contents with Mackerel and Zabbix”. For those of you who are too far away to come to the Meetups in Tokyo, be sure to join us and the Mackerel UG Kansai branch.

Check out the event page below for more details. (Japanese only)

Event details

【Advanced release notice】Specification changes for the host update API

Thank you for choosing Mackerel.

With the release scheduled for January 30, 2019 (Wednesday), changes will be made to the specifications of the host update API in order to make posting check reports with the API even more convenient.

The contents of these changes follow below.

Before the changes

With the host update API, in addition to the host's own information, you can send a list of check monitors that monitor the host and that list is synchronized with the check monitors in Mackerel.

Under the current specifications, if reports of check monitors not included in this list are posted to the host, the reports will be deleted and any open alerts will be closed automatically when the host information is updated.

The agent periodically updates the host’s information internally using the host update API and sends it together with a list of the check monitors described in the agent configuration file. With this mechanism, the configuration file and the check monitors in Mackerel are synchronized, and the check monitors that are deleted when the configuration file is updated are also deleted in Mackerel.

After the changes

The specification that synchronizes the host update API and the list of check monitors will change in the following ways:

When there are reports of check monitors that are not included in the list that was previously posted to the host...

  • If an alert related to that check monitor is opened, then the check monitor result will not be deleted in Mackerel and the alert will remain open.
  • If an alert related to that check monitor has not occurred, as with the current specifications, the check monitor results will be deleted in Mackerel.

Intention of the specification changes

As previously mentioned above, the agent internally uses the host update API to periodically synchronize the check monitors described in the agent configuration file with Mackerel. For this reason, according to the current specifications, if using the check report posting API from outside the agent to post reports to the host, and if check monitors are not included in the agent configuration file, deletions periodically happen regardless of whether or not an alert has occurred. And because of this, the display of check reports in Mackerel and use of the alert function can not be used normally.

With the specification change, even if check reports are posted from outside the agent, even if check monitors are not included in the agent configuration file, reports will no longer be deleted in Mackerel when an alert has occurred and the alert function can be used normally.

As a reminder, if there are no open alerts, the check reports will be deleted in Mackerel, same as with the current specifications. For this reason, there may be a difference in the display of check reports in the host detail screen, depending on the timing of the host information update and when check reports are posted from outside the agent. Please take this into consideration before using the API.

Thank you for your cooperation.

Invitation list now obtainable from the API and more

Mackerel team CRE Miura (id:missasan) here.

The other day, we released an entry announcing the Mackerel Ambassador Program. The eye-catching image used in that announcement was actually created by id:mazco who recently joined the Mackerel team as a designer. We wanted an image that captured a feeling of celebration for the start of the new program. id:mazco really delivered and made this bright and cute design that resembles a popping party cracker. We’re really looking forward to all the new Mackerel designs, not only with media-related designs like these, but also for the UI/UX, novelty gifts, and more.

Now on to this week’s update information.

Invitation list now obtainable from the API

You can now obtain a list of email addresses invited to organizations, permissions granted, and invitation expiration dates via the API.

Communication via TLS1.1 stopped

As was announced in the entry below, communication via TLS1.1 has been stopped. For more details, check out the following link.

Revisions made to Mackerel’s Terms of Service

Revisions were made Mackerel's Terms of Service on Tuesday, January 15th. Check out the entry below for details on the changes.

Issue fix for Japanese character corruption during plugin execution with Windows

The issue of Japanese character corruption during plugin execution for Windows was fixed with the release of mackerel-agent v0.59.0.

check-disk plugin now supported in Windows environments

Up until now, an inode check was always performed with the check-disk plugin even if only the -w / -c option was specified. Because of this, the plugin was not compatible in Windows environments where inodes do not exist. With the release of go-check-plugins v0.27.0, checking for inodes can be skipped when only the -w / -c option is specified. With this, the check-disk plugin is now also available in Windows environments.

In addition to this, with the release of mackerel-agent v0.59.0, the check-disk plugin is now also included in the mackerel-agent installer for Windows.

evicted_keys added to mackerel-plugin-redis metrics

With the release of mackerel-agent-plugins v0.54.0, evicted_keys has been added to the metrics of mackerel-plugin-redis.

Multiple metrics added to mackerel-plugin-squid

With the release of mackerel-agent-plugins v0.54.0, multiple new metrics have been added to the metrics of mackerel-plugin-squid.

Connecting without a password now possible with mackerel-plugin-postgres

With the release of mackerel-agent-plugins v0.54.0, it is now possible to connect with mackerel-plugin-postgres without a password.

A big thanks to everyone who contributed pull requests!

The Mackerel Ambassador Program has launched!


Hello! Mackerel team CRE Miura (id:missasan) here.

Here at Mackerel, we are extremely grateful for all of our users and their various activity regarding the Mackerel service.

Thanks to all of you and the positive feedback that’s been spread around, the word “Mackerel” can be heard on a regular basis over SNS and among the engineering crowd, known as a reliable choice and for its technical capabilities. In order to show our gratitude and give back, we’ve set up a new program called Mackerel Ambassadors!

As a perk, for those certified as an Ambassador, we now offer a special plan. With the Ambassador Plan, all features, including those only available with a paid plan as well as new features added in the future, can all be used free of charge. With this, we hope to receive even more honest feedback, so as to better understand the perspective of Mackerel users and their expectations. In addition, all feedback received will be used as a reference for future development and service operation.

The Mackerel team will contact you if you have been certified as an ambassador. Look forward to hearing from us!

How Ambassadors are selected

The Mackerel Ambassador Selection Committee will reach out to those who have been recognized to have utilized Mackerel in a profound way. They will directly contact users via email, SNS direct message, etc.

In the beginning, Ambassadors will be appointed through individual recommendations from the Mackerel team, but as the program grows, selections will be made based on the review of submitted applications.

The criteria for the process will not be made public.

The benefits of being an Ambassador

  • Use of the Mackerel Ambassador Plan
    • Register up to 10 hosts
    • Use all Mackerel features at no cost, including those in a paid plan
  • Novelty present priority
    • Apparel such as t-shirts and parkers
    • Stickers, Japanese style folding fans, pouches, glass cleaning cloth

Write a blog for the Ambassador Program

We are asking for Mackerel Ambassadors to submit a blog entry detailing their comments, impressions, or requests regarding a Mackerel feature that they put to use with the Ambassador Plan.

  • Thoughts or impressions of a feature
  • Feedback or requests for a feature
  • Things you like/don’t like about Mackerel

These are just some examples, so please feel free to write in more detail about whatever interests you. When we receive a blog entry, we’ll share the blog URL from Mackerel's official account and from individual Mackerel team member accounts etc. Depending on the content of the article, we may even share it on Mackerel's official blog.

Getting started

Regarding participation in the program, we will contact those who have accepted an ambassador position individually.

On January 23rd (Wed.), browsing for Mackerel documents will be unavailable for a short period of time between 1:00-3:00 a.m.

Thank you for choosing Mackerel.

Maintenance for Hatena Blog is scheduled to be carried out on January 23rd (Wednesday).

1月23日(水)午前1:00〜3:00ごろまでメンテナンスを行います - はてなブログ開発ブログ (Japanese only)

And because Mackerel documents are provided using the Hatena Blog feature, document browsing will be temporarily unavailable during the following time period.

Please note that this maintenance will not affect Mackerel's main service.

We apologize for the inconvenience and thank you for your understanding in our efforts to provide a more stable service.

Revisions to Mackerel’s Terms of Service

Thank you for choosing Mackerel.

Revisions have been made to the Mackerel Terms of Service. The revised content is as follows.

Terms of Service Japanese version

  • In Article 4 (Protection of Information), the fact that the user holds the rights to user posted data was added
  • Article 8 (Suspension and Cancellation of a Paid Plan by the User) was added
  • The existing Article 8 was converted to Article 9, and the following article numbers were shifted
  • Typos corrected

Terms of Service English version

Same as the above

Terms of Service (Mackerel for KCPS users)

Same as the above

This concludes the content revisions made to the Terms of Service.