Subscribed unsubscribe Subscribe Subscribe

Mackerel blog #mackerelio

The Official Blog of Mackerel

Regarding response body checks and redirects of URL external monitoring and future plans

Mackerel Sub-producer id:Songmu here. Thank you very much for choosing Mackerel. This is an announcement regarding the titled subject matter.

As stated in the help page, 2xx / 3xx type status codes are considered normal in the URL external monitor feature. Additionally, redirects are not checked for 3xx type responses.

Even if “response body check” is configured, it will not be performed if the response type is 3xx. Thus, if you currently have monitoring set up for URLs that return 3xx responses, the response body check is not being performed.

We realize this behavior is not intuitive, and we plan to change it so that if “response body check” is configured, the string will be checked even for 3xx responses.

In this case, we plan on performing string checks for the response body of 3xx type HTTP responses. The URL external monitoring feature checks the HTTP response by itself in order to not follow the redirect.

As an example, returns the 301 redirect to The output appears as shown below when accessed with curl (the output is abbreviated).

% curl -v
> GET / HTTP/1.1
> Host:
> User-Agent: curl/7.51.0
> Accept: */*
< HTTP/1.1 301 Moved Permanently
< Date: Thu, 20 Apr 2017 10:28:57 GMT
< Content-Type: text/html
< Content-Length: 178
< Connection: keep-alive
< Location:
<head><title>301 Moved Permanently</title></head>
<body bgcolor="white">
<center><h1>301 Moved Permanently</h1></center>

In this case, the section beginning with <html> will be the response body of this HTTP response, and the string check of the “response body check” will be done for this content.

Such being the case, please take a moment to review the settings concerning monitoring items which configure the “response body check” in the URL that returns 3xx type responses. Specifically, any of the following responses are assumed. If such a configuration is already set, changing the configuration is not necessary.

  • Configuring the URL to that which returns 2xx instead of 3xx
  • Deleting the “response body check” configuration
  • Configuring “response body check” for the string included in the 3xx response itself in preparation for future specification changes

We are also considering creating a configuration option in future feature expansions to follow and check the redirect for 3xx responses.


  • Currently, response body checks are not performed for 3xx type responses
  • We plan to make changes so that the response body of the original response is checked
    • Please update the configuration as necessary
  • We are considering adding options in future feature expansions to follow 3xx type redirects

Thanks again for choosing Mackerel.

Updates for mackerel-agent and mackerel-agent-plugins/A portion of OS support has been stopped etc.

The view of outside from the window has become completely green. How about for all of our Mackerel users out there?

And It’s about that time when this year’s new employees start getting used to work life.

Recently, Mastodon has been a really hot topic in Japan! Setting aside how it’s used, you could learn a lot from building your own Mastodon instance. If you do build one, be sure to monitor the server with Mackerel!

Anyways, here is this week’s update information.

Updates for mackerel-agent and mackerel-agent-plugins

Updates have been made for mackerel-agent and mackerel-agent-plugins. The specifics are listed below.

mackerel-agent v0.42.2

  • Included in mackerel-agent for Windows, the line endings of mackerel-agent.conf were set to CRLF
    • This makes editing possible even in Windows’ standard Notepad etc.
  • Other minor modifications

mackerel-agent-plugins v0.26.0

  • mackerel-plugin-aws-kinesis-streams was added
  • mackerel-plugin-aws-lambda was added
  • an error in the mackerel-plugin-redis metric label was corrected
  • mackerel-plugin-twemproxy now supports twemproxy v0.3

Thank you to everyone who contributed pull requests to the GitHub repository!

The deadline to apply for Mackerel Meetup #10 is approaching!

Tomorrow is the last day to apply for Mackerel Mackerel Meetup #10 and join us in celebrating our 10th Mackerel Meetup!

Due to it’s popularity, we’ve increased the maximum number of spots available from 70 to 80! And although all applicants will be selected through a lottery process, you’ve got a really good chance, so definitely apply!

OS Support stoppage notice

Along with the suspension of OS support, Mackerel plans to stop OS support for the following as of next month (May 2017).

  • CentOS5
  • Debian6
  • Ubuntu12.04

Even with support suspended, we do not anticipate any problems such as mackerel-agent suddenly freezing or server monitoring going down. Additionally, there are no plans to delete package repositories etc. at the moment. However, we can not guarantee that mackerel-agent will run with future updates.

We will make another announcement when support is officially stopped.

From now on as well, Mackerel plans to stop OS support according to the support end date of each OS. Regarding the supported environments of Mackerel and mackerel-agent, please refer to the following page.

Threshold input fields can now be seen upon first view when creating monitoring rules etc.

Hey! Mackerel sales engineer Inoue (id:a-know) here.

Just when I think that the spring weather will stay warm, a cold and windy day takes me by surprise. This season is really difficult to dress for…

But Golden Week (a Japanese holiday) is just around the corner and when that’s over, it’ll start to feel a lot like summer. So if you think about it like that, we should try and fully appreciate spring while it lasts.

Anyways, here is this week’s update information.

Threshold input fields can now be seen upon first view when creating monitoring rules

We made this feature update based on feedback that we received that expressed wanting to have threshold configuration in first view since it changes at a high frequency. With this, it is easier to make changes and understand the purpose/options available from this screen. Be sure to check it out.

The font set has been changed

With an aim to improve character visibility/readability, Mackerel designers tested out a variety of fonts in various environments and implemented a new font.

The following image is an side-by-side comparison using a section of the side menu. The left side is the previously used font and the right side is the updated version.

The scroll bar display has been improved

In Webkit browsers, scroll bars are not initially displayed even in areas that can be scrolled. Up until now, scroll bars appear upon scrolling. We felt this gave the interface a simpler aesthetic, but the Mackerel designers thought that it might be better to be able to see which areas can be scrolled in advance.

We vigorously discussed within issues, pull requests, etc. and as a result, we decided to make scroll bars visible when hovering the cursor over areas that are constantly displayed and always show for areas that are added afterwards.

Here at Mackerel, we are making more improvements than ever in order to be easier to understand and easier to use. Look forward to future UI improvements as well!

Release of mackerel-agent v0.42.1

mackerel-agent has been updated. The following change has been made.

  • Locale information( LC_ALL=C )will now be configured when initializing the agent

Now accepting applications for Mackerel Meetup #10!

As an official Mackerel event, we are commemorating the 10th Mackerel Meetup. We are now accepting applications!

This time we’ll be borrowing the lovely venue of Microsoft Japan!

We’ve got all sorts of things lined up! The main content for the event is as follows.

Time Title Speaker・MC
19:20-19:30 Important points in advance Hatena
19:30-19:50 Microsoft Azure Integration and Strengthening Windows Support Hatena Co., Ltd.
Mackerel Producer, Hiromichi Sugiyama(id:sugiyama88)
19:50-20:10 MTI Healthcare platform supported by Mackerel + Azure MTI Ltd.
Norio Akama
20:10-20:30 Introducing Vuls vulnerability scanner and exploring vulnerability management using Mackerel metadata Future Architect Co., Ltd.
Vuls Developer, Kota Kanbe
20:30-20:40 Questionnaire and get-together preparation time Hatena
20:40-22:00 Get-together・LT tournament Hatena・LT Presenters

With Vuls in cooperation with Microsoft Azure, this is an event you definitely don’t want to miss!

Monitoring rules that correspond to alerts have become easier to identify etc.

Hello. Sales engineer id:Soudai here.

Spring is in full bloom and I’ve noticed a lot of people who have recently started working walking beneath the cherry blossoms. It reminds me of my original intentions with joining Mackerel of showing everyone just how amazing it is.

Anyways, here is this week’s update information.

Monitoring rules that correspond to alerts have become easier to identify

When an alert occurs, it is now easier to identify for which monitoring rule the alert is occurring from the host details screen. An example is shown below.

Normally, “Monitors” are displayed in the host details like the image below.

Using the configured monitoring rules in the images above as an example, when the threshold defined by “CPU %” is exceeded, the corresponding monitoring rule will be displayed at the top of the list as shown below.

This way, even if an alert occurs for a host with many monitoring rules, it’s easier to quickly figure out for which monitoring rule the alert is occurring.

Mackerel continues to work on updates that will improve everyday utility.

Updates for the agent, plugins, and more

mackerel-agent v0.42.0

  • minor corrections were made

mackerel-agent-plugins v0.25.6

  • minor corrections were made

go-check-plugins v0.10.0 / mkr v0.15.0

  • you can now build with Go 1.8

Mackerel to participate as a silver sponsor for AWS Summit Tokyo 2017

Mackerel will participate as a silver sponsor at the AWS Summit Tokyo 2017 which will be held from May 30th (Tue) to June 2nd (Fri) 2017.

AWS Summit Tokyo 2017(2017年5月30日~6月2日)|AWS (Japanese only)

協賛スポンサー一覧 - AWS Summit Tokyo 2017(2017年5月30日~6月2日)|AWS (Japanese only)

Mackerel will be running a booth throughout the four day event.

If any of you out there have questions concerning topics like “How to monitor with AWS” and “How Mackerel works”, by all means, please stop by the Mackerel booth!

Memos left for monitoring rules can now be seen in alert notifications

Hello! Sales engineer id:Soudai here.

The weather has really started to warm up over the last week and I’m sure a lot of people will be out and about to see the cherry blossoms this weekend. I’m looking forward to taking a stroll myself and enjoying spring atmosphere.

Anyways, here is this week’s update information.

Memos left for monitoring rules can now be seen in alert notifications

We’ve expanded upon the recently released memo feature for monitoring rules. Memos are now also displayed in the alert details screen and notification channel when alerts occur. The channels that display monitor memos from alert notifications are as follows.

  • Slack
  • HipChat
  • ChatWork
  • Typetalk
  • OpsGenie
  • Reactio
  • Yammer

Whether identifying alert content or for maintenance purposes, alerts will become very clear. By all means, give it a try.

With the ability to write yourself a note on how to handle the next alert, possible causes, etc., this feature can be extremely useful.

Slack notifications

Alert details screen

mkr command v0.14.5 has been released

Color has been added to part of the output result when the Windows version mkr command is executed. This makes things a lot easier to understand when viewing the alerts list. For those of you who haven’t been using the mkr command, definitely give it a try.


The following have also been released

  • go-check-plugins v0.9.7 has been released
  • Parameter check fixed
  • mackerel-agent v0.41.3 has been released
  • Windows version stabilized

A joint Hands-On Seminar for 3 services

Mackerel, AWS, and Twilio will hold a joint hands-on seminar on Tuesday, April 25th. Definitely consider applying if you meet any of the following:

  • Infrastructure engineers and application engineers
  • Those who are interested in, but do not have experience in server monitoring or monitoring related work
  • Those who are interested in optimizing the server monitoring and notification systems of their company
  • Those who might have heard of “Mackerel”, but aren’t exactly sure what it is
  • Those who are interested in creating an automated system with AWS Lambda
  • Those interested in automatic calls with Twilio

For more information about this hands-on seminar, please check out the application site below. Sales engineer id:a-know will be presenting for Mackerel, so look forward to that!

We hope to see you there!

Memos can now be left for monitoring rules using mkr commands

Hello! Sales engineer id:Soudai here.

The cherry blossoms have started to bloom a little early and it’s finally starting to feel like spring.

Mackerel Drink Up #4 Tokyo - connpass was held last week and a lot of people attended the event. We were able to exchange ideas on topics like plugin implementation and even had an LT tournament, all while enjoying a really fun atmosphere.

Here’s a report blog written by a participant.

I also participated in the LT tournament. Take a look at this as well.

If you were too busy and couldn’t make it this time, don’t worry! We’ll be holding these types of events regularly in the future. So by all means, join us next time!!

Anyways, here is this week’s update information.

Memos can now be be left for monitoring rules using mkr commands

Last week we released a feature that lets you leave notes for monitoring rules. Now, this feature is also supported by mkr. As before, by simply adding the memo item, this feature is easy to use when updating with mkr monitors.

Example use

% mkr monitors diff
   "critical": 2000,
   "duration": 1,
   "metric": "hoge.count",
   "name": "mackerel-demo - hoge.count",
+  "memo": "test"
   "operator": ">",
   "service": "mackerel-demo",
   "type": "service",
   "warning": 1000

% mkr monitors push

Now accepting applications for the Mackerel Hands-On Seminar

Starting from last year, the Mackerel Hands-On Seminar has been held 6 times. It’s an event where you can come and learn all sorts of things, from “why server monitoring is necessary” to Mackerel monitoring configurations and handling alerts in a practical workshop format. The first seminar of this year will be held on April 12th (Wed.). Definitely consider applying if you meet any of the following:

  • For those who are interested in, but do not have experience with server monitoring or monitoring related work
  • For those who might have heard of “Mackerel”, but aren’t exactly sure what it is
  • For those who are currently pursuing a job as an engineer

For more details, visit the application site linked below. We still have spots left, so please apply!

You can now leave notes for monitoring rules

Production has finally finished for the Mackerel glass, one of the gifts for the 2017 New Year campaign! We started shipping the other day so hopefully one will find its way to you soon.

If you’re selected, be sure to tweet with the hashtag #mackerelio!

We may be giving out more presents at Meetup and other official events in the future. You definitely don’t want to miss out! Anyways, here is this week’s update information.

You can now leave notes for monitoring rules

You can now leave notes for each monitoring rule set in Mackerel.

You can also create notes via the API.

Mackerel Drink Up #4 Tokyo!

Mackerel Drink Up is mainly a chance for our Mackerel users to come hang out at the Hatena Tokyo office, eat, drink, and talk about all sorts of things. The 4th Mackerel Drink Up will be held on Wednesday, March 22nd!

Mackerel Drink Up #4 Tokyo - connpass

This event is perfect for those of you who are curious to see how other users are using Mackerel or if you would like to speak to the Mackerel staff directly. Those who wish to attend will be chosen by lottery due to the limited number of spots, but there are still plenty available, so by all means, apply!