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NOTICE: This software (or technical data) was produced for the U.S. Government under contract, +and is subject to the Rights in Data-General Clause 52.227-14, Alt. IV (DEC 2007). Copyright 2023 +The MITRE Corporation. All Rights Reserved.

+

Health Check Overview

+

The C++ and Python component executors can be configured to run health checks on components prior +to running jobs. Health checks are configured using environment variables and an INI file.

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When the component executor receives a job from ActiveMQ, it checks if health checks are enabled +and if more than the specified timeout has passed since the last health check. If both conditions +are true, the component executor will run a health check job before the actual job. Health checks +only run after a job from ActiveMQ is received. If the timeout period expires, but no job is +received or a job is already running, the health check will not run until the next job is received.

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If the health check job completes successfully, then component executor runs the job received from +ActiveMQ. If the health check fails, the job will be returned to ActiveMQ. If the maximum number of +consecutive health failures has been met, the component executor will exit with exit code 39. +Otherwise, the component executor will wait the timeout period before until attempting to receive +another job from ActiveMQ.

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Environment Variables

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  • HEALTH_CHECK: When set to "ENABLED", the component executor will run health checks.
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  • HEALTH_CHECK_TIMEOUT: When set to a positive integer, specifies the minimum number of seconds + between health checks. When absent or set to 0, a health check will run before every job.
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  • HEALTH_CHECK_RETRY_MAX_ATTEMPTS: When set to a positive integer, specifies the number of + consecutive health check failures that will cause the component service to exit. When absent or + set to 0, the component service will never exit because of a failed health check.
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The INI File

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When health checks are enabled, the component executor will look for an INI file at +$MPF_HOME/plugins/<component-name>/health/health-check.ini. Below is an example of the expected +INI file.

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media=$MPF_HOME/plugins/OcvFaceDetection/health/meds_faces_image.png
+min_num_tracks=2
+media_type=IMAGE
+
+[job_properties]
+JOB PROP1=VALUE1
+JOB PROP2=VALUE2
+
+[media_properties]
+MEDIA PROP=MEDIA VALUE
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The supported keys are:

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  • media: (Required) Path to the media file that will be used in the health check.
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  • min_num_tracks: (Required) The minimum number of tracks the component must find for the health + check to pass.
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  • media_type: (Required) The type of media referenced in the media key. It must be one of + "IMAGE", "VIDEO", "AUDIO", or "GENERIC".
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  • job_properties: (Optional) Job properties that will set on the health check job.
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  • media_properties: (Optional) Media properties that will set on the health check job.
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