Run anomaly detection jobs

Anomaly detection jobs contain the configuration information and metadata necessary to perform the machine learning analysis. They can run for a specific time period or continuously against incoming data.

Before you can use the Elastic Stack machine learning features, there are some configuration requirements (such as security privileges) that must be addressed. Refer to Setup and security.

You can create anomaly detection jobs by using the create anomaly detection jobs API. Kibana also provides wizards to simplify the process, which vary depending on whether you are using the Machine Learning app, Elastic Security app or Observability apps. In Machine Learning > Anomaly Detection:

Kibana can also recognize certain types of data and provide specialized wizards for that context. For example, there are anomaly detection jobs for the sample eCommerce orders and sample web logs data sets, as well as for data generated by the Elastic Security and Observability solutions, Beats, and Elastic Agent Integrations. For a list of all the preconfigured jobs, see Supplied configurations.

When you create an anomaly detection job in Kibana, the job creation wizards can provide advice based on the characteristics of your data. By heeding these suggestions, you can create jobs that are more likely to produce insightful machine learning results. The most important concepts are covered here; for a description of all the job properties, see the create anomaly detection jobs API.

The machine learning features use the concept of a bucket to divide the time series into batches for processing.

The bucket span is part of the configuration information for an anomaly detection job. It defines the time interval that is used to summarize and model the data. This is typically between 5 minutes to 1 hour and it depends on your data characteristics. When you set the bucket span, take into account the granularity at which you want to analyze, the frequency of the input data, the typical duration of the anomalies, and the frequency at which alerting is required.

The bucket span must contain a valid time interval. When you create an anomaly detection job in Kibana, you can choose to estimate a bucket span value based on your data characteristics. If you choose a value that is larger than one day or is significantly different than the estimated value, you receive an informational message.

Each anomaly detection job must have one or more detectors. A detector defines the type of analysis that will occur and which fields to analyze.

Detectors can also contain properties that affect which types of entities or events are considered anomalous. For example, you can specify whether entities are analyzed relative to their own previous behavior or relative to other entities in a population. There are also multiple options for splitting the data into categories and partitions. Some of these more advanced job configurations are described in Examples.

If your job does not contain a detector or the detector does not contain a valid function, you receive an error. If a job contains duplicate detectors, you also receive an error. Detectors are duplicates if they have the same function, field_name, by_field_name, over_field_name and partition_field_name.

When anomalous events occur, we want to know why. To determine the cause, however, you often need a broader knowledge of the domain. If you have suspicions about which entities in your data set are likely causing irregularities, you can identify them as influencers in your anomaly detection jobs. That is to say, influencers are fields that you suspect contain information about someone or something that influences or contributes to anomalies in your data. Influencers can be any field in your data.

You can pick influencers when you create your anomaly detection job by using the Advanced job wizard.

Picking an influencer is strongly recommended for the following reasons:

If you use Kibana, the job creation wizards can suggest which fields to use as influencers. The best influencer is the person or thing that you want to blame for the anomaly. In many cases, categorical data fields – like users or client IP addresses – make excellent influencers.

The Anomaly Explorer in Kibana lists the top influencers for a job and shows the most influental values for every anomaly. It also enables you to filter the data by a given influencer.

Refer to this blog post for further details on influencers.

If there are logical groupings of related entities in your data, machine learning analytics can make data models and generate results that take these groupings into consideration. For example, you might choose to split your data by user ID and detect when users are accessing resources differently than they usually do.

If the field that you use to split your data has many different values, the job uses more memory resources. In Kibana, if the cardinality of the by_field_name, over_field_name, or partition_field_name is greater than 1000, the job creation wizards advise that there might be high memory usage. Likewise if you are performing population analysis and the cardinality of the over_field_name is below 10, you are advised that this might not be a suitable field to use.

For each anomaly detection job, you can optionally specify a model_memory_limit, which is the approximate maximum amount of memory resources that are required for analytical processing. The default value is 1 GB. Once this limit is approached, data pruning becomes more aggressive. Upon exceeding this limit, new entities are not modeled.

You can also optionally specify the xpack.ml.max_model_memory_limit setting. By default, it’s not set, which means there is no upper bound on the acceptable model_memory_limit values in your jobs.

If the estimated model memory limit for an anomaly detection job is greater than the model memory limit for the job or the maximum model memory limit for the cluster, the job creation wizards in Kibana generate a warning. If the estimated memory requirement is only a little higher than the model_memory_limit, the job will probably produce useful results. Otherwise, the actions you take to address these warnings vary depending on the resources available in your cluster:

If you are using Elastic Cloud Enterprise or the hosted Elasticsearch Service on Elastic Cloud, xpack.ml.max_model_memory_limit is set to prevent you from creating jobs that cannot be allocated to any machine learning nodes in the cluster. If you find that you cannot increase model_memory_limit for your machine learning jobs, the solution is to increase the size of the machine learning nodes in your cluster.

For each anomaly detection job, you can optionally specify a dedicated index to store the anomaly detection results. As anomaly detection jobs may produce a large amount of results (for example, jobs with many time series, small bucket span, or with long running period), it is recommended to use a dedicated results index by choosing the Use dedicated index option in Kibana or specifying the results_index_name via the Create anomaly detection jobs API.

If you create anomaly detection jobs in Kibana, you must use datafeeds to retrieve data from Elasticsearch for analysis. When you create an anomaly detection job, you select a data view and Kibana configures the datafeed for you under the covers.

You can associate only one datafeed with each anomaly detection job. The datafeed contains a query that runs at a defined interval (frequency). By default, this interval is calculated relative to the bucket span of the anomaly detection job. If you are concerned about delayed data, you can add a delay before the query runs at each interval. See Handling delayed data.

Datafeeds can also aggregate data before sending it to the anomaly detection job. There are some limitations, however, and aggregations should generally be used only for low cardinality data. See Aggregating data for faster performance.

If the data that you want to analyze is not stored in Elasticsearch, you cannot use datafeeds. You can however send batches of data directly to the job by using the post data to jobs API. [7.11.0] Deprecated in 7.11.0.

An anomaly detection job must be opened in order for it to be ready to receive and analyze data. It can be opened and closed multiple times throughout its lifecycle.

After you start the job, you can start the datafeed, which retrieves data from your cluster. A datafeed can be started and stopped multiple times throughout its lifecycle. When you start it, you can optionally specify start and end times. If you do not specify an end time, the datafeed runs continuously.

You can perform both these tasks in Kibana or use the open anomaly detection jobs and start datafeeds APIs.

Typically after you open a job, the next step is to view the results. You might find that you need to alter the job configuration or settings.

Sometimes there are periods when you expect unusual activity to take place, such as bank holidays, "Black Friday", or planned system outages. If you identify these events in advance, no anomalies are generated during that period. The machine learning model is not ill-affected and you do not receive spurious results.

You can create calendars and scheduled events in the Settings pane on the Machine Learning page in Kibana or by using Machine learning anomaly detection APIs.

A scheduled event must have a start time, end time, and description. In general, scheduled events are short in duration (typically lasting from a few hours to a day) and occur infrequently. If you have regularly occurring events, such as weekly maintenance periods, you do not need to create scheduled events for these circumstances; they are already handled by the machine learning analytics.

You can identify zero or more scheduled events in a calendar. Anomaly detection jobs can then subscribe to calendars and the machine learning analytics handle all subsequent scheduled events appropriately.

If you want to add multiple scheduled events at once, you can import an iCalendar (.ics) file in Kibana or a JSON file in the add events to calendar API.

By default, anomaly detection is unsupervised and the machine learning models have no awareness of the domain of your data. As a result, anomaly detection jobs might identify events that are statistically significant but are uninteresting when you know the larger context. Machine learning custom rules enable you to customize anomaly detection.

Custom rules – or job rules as Kibana refers to them – instruct anomaly detectors to change their behavior based on domain-specific knowledge that you provide. When you create a rule, you can specify conditions, scope, and actions. When the conditions of a rule are satisfied, its actions are triggered.

For example, if you have an anomaly detector that is analyzing CPU usage, you might decide you are only interested in anomalies where the CPU usage is greater than a certain threshold. You can define a rule with conditions and actions that instruct the detector to refrain from generating machine learning results when there are anomalous events related to low CPU usage. You might also decide to add a scope for the rule, such that it applies only to certain machines. The scope is defined by using machine learning filters.

Filters contain a list of values that you can use to include or exclude events from the machine learning analysis. You can use the same filter in multiple anomaly detection jobs.

If you are analyzing web traffic, you might create a filter that contains a list of IP addresses. For example, maybe they are IP addresses that you trust to upload data to your website or to send large amounts of data from behind your firewall. You can define the scope of a rule such that it triggers only when a specific field in your data matches one of the values in the filter. Alternatively, you can make it trigger only when the field value does not match one of the filter values. You therefore have much greater control over which anomalous events affect the machine learning model and appear in the machine learning results.

For more information, see Customizing detectors with custom rules.

Elastic Stack machine learning features calculate baselines of normal behavior then extrapolate anomalous events. These baselines are accomplished by generating models of your data.

To ensure resilience in the event of a system failure, snapshots of the machine learning model for each anomaly detection job are saved to an internal index within the Elasticsearch cluster. The amount of time necessary to save these snapshots is proportional to the size of the model in memory. By default, snapshots are captured approximately every 3 to 4 hours. You can change this interval (background_persist_interval) when you create or update a job.

To reduce the number of snapshots consuming space on your cluster, at the end of each day, old snapshots are automatically deleted. The age of each snapshot is calculated relative to the timestamp of the most recent snapshot. By default, if there are snapshots over one day older than the newest snapshot, they are deleted except for the first snapshot each day. As well, all snapshots over ten days older than the newest snapshot are deleted. You can change these retention settings (daily_model_snapshot_retention_after_days and model_snapshot_retention_days) when you create or update a job. If you want to exempt a specific snapshot from this clean up, use Kibana or the update model snapshots API to set retain to true.

You can see the list of model snapshots for each job with the get model snapshots API or in the Model snapshots tab on the Job Management page in Kibana:

When historical data is analyzed, there is no need to stop the datafeed and/or close the job as they are stopped and closed automatically when the end time is reached.

If you need to stop your anomaly detection job, an orderly shutdown ensures that:

This process ensures that jobs are in a consistent state in case you want to subsequently re-open them.

When you stop a datafeed, it ceases to retrieve data from Elasticsearch. You can stop a datafeed by using Kibana or the stop datafeeds API. For example, the following request stops the feed1 datafeed:

POST _ml/datafeeds/feed1/_stop

A datafeed can be started and stopped multiple times throughout its lifecycle.

If you are upgrading your cluster, you can use the following request to stop all datafeeds:

POST _ml/datafeeds/_all/_stop

When you close an anomaly detection job, it cannot receive data or perform analysis operations. You can close a job by using the close anomaly detection job API. For example, the following request closes the job1 job:

POST _ml/anomaly_detectors/job1/_close

If you submit a request to close an anomaly detection job and its datafeed is running, the request first tries to stop the datafeed. This behavior is equivalent to calling the stop datafeeds API with the same timeout and force parameters as the close job request.

Anomaly detection jobs can be opened and closed multiple times throughout their lifecycle.

If you are upgrading your cluster, you can use the following request to close all open anomaly detection jobs on the cluster:

POST _ml/anomaly_detectors/_all/_close