Mackerel's and mackerel-agent's specs

What environments are supported by Mackerel?

For information about supported environments please refer to the “Supported Environments” section of the Mackerel Overview.

How do I have a re-created instance be recognized as the same host as before?

When you want to recreate an instance and have it still be recognized as the same host as before, by first backing up the file containing the host ID (saved by default in /var/lib/mackerel-agent/id; for more info check the Glossary) and inserting that file in the new instance, it will now be recognized as the same host by Mackerel.

However, please be aware that if the agent were to be running on multiple hosts with the same host ID file, those hosts would be recognized as the same host and monitoring and metrics posting would not be able to function properly.

What kind of configuration is Mackerel's connectivity monitoring working with?

  • When data from a mackerel-agent running on a host that has been registered to the Mackerel server is not being received for a period of time, it will be judged as NG.

How many times will notifications be sent until an alert is resolved?

  • Notifications will be sent only once each time an alert's status changes.
  • For example in a case where an alert's status reflects OK→Warning→Critical→OK, a total of 3 notifications will be sent, once each time the status changes.

What is the time interval between alert checks?

  • When the Mackerel management server is not receiving transmissions from the agent for a 10 minute period of time, it will be judged as NG.
  • Host metric monitors, and check monitors will be judged as OK/NG when data is sent to the Mackerel server.
  • Service metric monitors will be judged as OK/NG when metrics are sent to the Mackerel server.
  • External monitors will be checked and judged as OK/NG every minute.
  • There is a possibility that in the future the aforementioned check intervals will be revised.

How do the Mackerel server and the mackerel-agent communicate?

  • mackerel -agent communicates with the Mackerel server via its HTTP REST API.
    • No direct communication is done from the Mackerel server side to the host that contains mackerel-agent.
  • Encrypted with SSL/TLS correspondence.

Is it possible to control which port the mackerel-agent uses?

  • While it's not possible to control the port, we do support connection via proxy. For more information please refer to the section "I want to connect via HTTP Proxy." in the agent specs.

What IP address and port number is Mackerel hosted at?

  • Both mackerel.io and kcps-mackerel.io are hosted with the range below. In the event of a change, an announcement will be made in advance
    • as well as
  • The port number is 433.
  • mackerel-agent also makes requests with the above-mentioned IP address and port number.

What is the origin IP address of Webhook’s and other services’ alert notifications from Mackerel?

The IP address of origin of notification requests from Mackerel is In the event that we deem it necessary to change this IP address, an announcement will be made in advance.

About Organizations

About managerial authority in organizations…

  • The user who created the organization is its owner. After logging in as the owner, you can transfer ownership of the organization in the members list.
  • For the most part, only functions involved with payments and billing are owner-only access restricted.
  • Further expansion of user authority related features is currently in development.

I want to change my organization’s name or, I want to delete my organization.

  • If you would like to change an organization’s name or to withdraw from an organization, please log in to Mackerel and contact support by clicking on Feedback. https://mackerel.io/my?tab=setting
  • Your organization can't be deleted if you are either not the owner of the organization, or if there are other members in your organization. To delete your organization you must log in as the owner and delete all other members first.
  • Please keep in mind that it may not be possible to change your organization's name if that name is already being used.

I want to make a new organization.

  • To create a new organization, click the “Create” button in the “Change Organization” drop down menu in the top left-hand corner of the screen.


The agent won’t startup.

  • It's a good idea to first check and see if the package has been properly installed or not.
  • If you have included /var/lib/mackerel-agent/id into an OS image such as Docker Image or AMI, it will be necessary to delete this file.
    • When the mackerel-agent starts up for the first time, the ID issued by the server will be saved to /var/lib/mackerel-agent/id. The host will be identified by this ID from then on. For that reason, if /var/lib/mackerel-agent/id is copied, multiple hosts will be recognized by Mackerel as the same host, resulting in metric posting and monitoring not functioning properly.

Graphs aren't being displayed in Mackerel and it seems like data isn't being posted.

  • First check and see if the mackerel-agent is running or not.
  • If the agent is running, check to see if the server's time is configured correctly.
    • If there is a discrepancy between the configured time and the actual current time, there is possibility that data will not be posted correctly.
  • There is a short time lag between registering a new host and the first metrics post from that host.

I set up monitoring rules but I’m still not getting alert notifications.

  • In order to receive alert notifications, hosts must be set to the “Working” status.
  • The default status for newly registered hosts can be changed in the Settings tab of your organization’s details page. https://mackerel.io/my?tab=setting
    • By setting the default status to “Working”, you can receive alert notifications immediately after registering a new host.
  • For more information regarding the relationship between hosts’ statuses and notifications, please refer to [Setting up monitoring and alerts]https://mackerel.io/docs/entry/howto/alerts).

I’m not receiving any emails.

Account confirmation, alert notification, and other various emails are sent from Mackerel. If for some reason emails from Mackerel are not appearing, please refer to the following list of possible causes.

  • Can’t receive emails from noreply@mackerel.io.
    • If you are using email filtering, please make sure that your filter settings are configured so that mackerel.io emails are able to be received.
  • Mail from mackerel.io gets recognized as spam.
    • If emails from Mackerel are being put filtered as spam or junk mail, please check your spam filter settings. If you are using gmail, please refer to the gmail support page. ( https://support.google.com/mail/answer/9008 )
    • mackerel.io is an SPF-verified domain. In your spam filter settings, there should be a option to not tag mail from SPF-verified domains as spam.
  • Not receiving alert notification emails.
    • If you have not yet completed registration, alert notification emails will not be sent. To begin receiving alert notification email, please complete registration by verifying your account via the account verification email that was sent.

About plans and contracts

How is the number of hosts calculated?

The number of hosts will be calculated as follows:

  • The number of active hosts will be counted periodically in time intervals of about 1 hour.
    • The number of unique hosts that have accessed the metric posting API will be included regardless of those hosts’ statuses.
    • Normally this number will equal the number of mackerel-agents being run.
    • Hosts with a “retired” status will not be counted as active hosts.
  • The total number of hosts will be calculated based on a 30 day period of use, otherwise if you have not yet used the service for 30 days, calculation will be based on the average number of active hosts per day so far (rounded up).
  • When using a paid plan, even if the the number of active hosts is zero, the minimum usage fee (one host’s worth) will be charged once.

Handling of host conversion when plan limits are exceeded

In addition to the previous section, here we will explain how host conversion will be done in response to plan overages of each type of item. All decimal points will be rounded up.

  • Host metrics
    • overage ÷ plan limit (200 for Standard plans)
    • calculation will be done in regard to all hosts exceeding the limit
    • hosts' host metrics will be calculated with the equation below
      • Standard metrics + custom metrics + check monitors
  • Service metrics
    • overage ÷ plan limit (200 for Standard plans)
  • External monitors
    • overage ÷ plan limit (20 for Standard plans)

Two examples using the Standard plan

The Standard plan has multiple limits, for host metrics it's 200, for service metrics 200, and for external monitors the limit is 20.

Below are 2 example possible use cases.

Pattern A usage overage host conversion
Host A metrics 180 0 0
Host B metrics 180 0 0
Host C metrics 180 0 0
Service metrics 90 0 0
External monitors 19 0 0

In this case there are three hosts, A, B, and C, and no overages, so total hosts will be counted as 3.

Pattern B usage overage host conversion
Host A metrics 401 201 2
Host B metrics 180 0 0
Host C metrics 180 0 0
Service metrics 240 40 1
External monitors 30 10 1

In this case we have 3 hosts, plus 4 hosts converted from overages, making a total of 7 hosts.

If the total calculated number of hosts has exceeded your plan’s limit, a notification will appear in Mackerel and you will also be notified via email, at which time we hope you will consider increasing your plan’s limit. We also have plans that charge based on how many hosts are in use, so if you find it troublesome adjusting your contract's number of hosts please let us know.

Please be aware that if your plan’s limit is exceeded and goes on unchanged, there is a possibility your account may be suspended or other means may be taken.

Cost calculation when changing the number of hosts…

The number of hosts that was set when your account was created may be increased or decreased at any time. Calculation of changes made to the number of hosts will be done in following procedure.

  • When increasing the number of hosts, additional charges will be calculated by the number of hosts added multiplied by the per-diem rate.
  • If you have decreased the number of hosts, unfortunately we are not able to issue refunds for those hosts.
  • In either case, calculation of charges after changes have been made to the number of hosts will be done at the time of the next scheduled payment.

How is the number of host to be billed calculated?

The number of hosts will be calculated using the moving average from the past month. The average will be used, not the max simultaneous activation number or the total. For example, even if the amount of servers drastically increased temporarily in order to take measures against a high load capacity, the usage fee would not increase by a large margin.

Again, in the case of a large number of host metrics and service metrics, the number of hosts will be converted as shown in the above appendix. For more details, please take a look at the “How is the number of hosts calculated?” section.

How will the usage fee be affected if the moving average is a decimal?

In the case that the moving average number of hosts is a decimal, it will be rounded up. For example, a value of 3.7 will be counted and charged as 4.

Again, even if the moving average number of hosts is 0, it will be charged as 1 as per the minimum usage fee. Thereby, subscribing to the Standard Plan in order to use the URL external monitoring and not registering any hosts, the minimum of 1 host will be charged.

Payment timing

The actual usage from the previous month will be charged every first of the month (in Japan Standard Time). As for the month in which the contract began, the amount of days used will be taken into account when calculating the usage fee.


How can I stay up to date on Mackerel’s ongoing development?

If you have encountered a problem within Mackerel, it’s likely we are in the process of working to fix it. To see the latest information and updates about development, please follow us on twitter @mackerelio or subscribe to our status page status.mackerel.io.

I want to change my email address linked to IDCF.

When using an organization in connection with IDCF, if you change your email associated with your IDCF account, those changes will not be reflected in your Mackerel account. If you want to use Mackerel with the new email address please follow the steps below to create a new user account with the changed email address.

  1. Log in to your current account and send a member invite to the email address you'd like to use from the list of members page.
  2. Change the organization's management authority holder from you current account to the new account. This can be done in the list of members screen. ( https://mackerel.io/docs/entry/faq#transfer-ownership )
  3. Delete your current account's IDCF connection in the user settings.
  4. Log out and log back in with your new account and set up IDCF connection in user settings.
  5. If necessary you can now delete your previous account from the organization in the list of members.


If you have any questions please contact our support team at support@mackerel.io