Runtime parameters

Customize a container’s behavior at runtime.

4 minute read

When you start an API Gateway, Admin Node Manager, or API Gateway Analytics container, you can customize its behavior at runtime:

  • You can pass one or more environment variables to the docker run command.
  • You can add a file to a container at runtime, leveraging Docker data management capabilities, such as volumes or bind mounts.

Environment variables reference

You can specify both externally managed topology (EMT) environment variables and core platform system variables when starting Docker containers.

Environment variables for controlling an EMT system are prefixed with EMT_.

Variable Name Description
EMT_ANM_HOSTS Enables the API Gateway to communicate with the Admin Node Manager container through the port specified. Specify a comma-separated list of Admin Node Manager containers that a gateway should register with. Sample usage: -e EMT_ANM_HOSTS="anm-ds1:8090,anm-ds2:8090"
EMT_DEPLOYMENT_ENABLED Enables deploying changes to a running container by way of Policy Studio only. This parameter should only be used in a development environment. Deploying a new FED into a container does not update the associated image, and a new API Gateway container will continue to use the old FED. In production, the FED updates should be incorporated into a new image and deployed via a rolling update. Sample usage: -e EMT_DEPLOYMENT_ENABLED=true
EMT_TOPOLOGY_LOG_DEST Specifies the destination to which topology log records are written. Possible values: 1 (Topology log), 2 (Trace log), 3 (both). Defaults to 1.
EMT_TOPOLOGY_LOG_DIR The directory into which topology logs are written. Defaults to /opt/Axway/apigateway/logs. If you mount this directory as a volume, you can set a location outside the container to write the logs.
EMT_TOPOLOGY_LOG_ENABLED Specifies whether topology logging is enabled or disabled. Possible values: true, false. Defaults to false.
EMT_TOPOLOGY_LOG_INTERVAL Time interval, in seconds, between successive log records for each gateway. Defaults to 60. Maximum value: 3600. For example, if set to 60, then a log record is written once a minute for each gateway, recording the number of transactions since the last log record was written.
EMT_PARENT_HOST Identifies the host on which the API Gateway container is running.
EMT_HEAP_SIZE_MB Specifies the initial and maximum Java heap size for the Admin Node Manager, API Gateway, or API Gateway Analytics process. JVM processes within a Docker container sometimes set their heap size from the host machine’s limits, thereby choosing a value that is too high. This parameter can be used to limit the JVM’s memory footprint. Sample usage: -e EMT_HEAP_SIZE_MB=4096
EMT_TRACE_LEVEL Specifies the trace level for an Admin Node Manager or API Gateway container. This can be useful for debugging issues in the runtime environment without having to build a new image. Possible values: INFO, DEBUG, DATA. Defaults to INFO. Sample usage: -e EMT_TRACE_LEVEL=DEBUG
EMT_POLL_INTERVAL The frequency, in seconds, with which an API Gateway container transmits registration requests to all Admin Node Managers in EMT_ANM_HOSTS. Admin Node Managers use these registration requests to dynamically build up a picture of the topology, which is then displayed in the API Gateway Manager UI. This parameter has default value 30, and should not normally need to be set explicitly. Sample usage: -e EMT_POLL_INTERVAL=35
EMT_TOPOLOGY_TTL The time, in seconds, that an Admin Node Manager container will wait without receiving a registration request from a gateway before it deletes that gateway from the topology. When a gateway is removed from the topology, it disappears from the topology view in the API Gateway Manager UI. This could occur, for example, if the container orchestration framework scales down the number of gateway containers in response to dropping traffic levels. This parameter has default value 120, and should not normally need to be set explicitly. Sample usage: -e EMT_TOPOLOGY_TTL=140
CASS_HOST Apache Cassandra host used to store the API Manager data.
METRICS_DB_URL URL to connect with the metrics database.
METRICS_DB_USERNAME User name to connect with the metrics database.
METRICS_DB_PASS Password to connect with the metrics database.

Add files to containers in a runtime environment

Many files can be added to images at build time. Sometimes, files contain information that is only known in a runtime environment. Such files can be added at container startup by using Docker bind mounts. For more details, see the included in the Docker scripts package.

For example, a mount point is /merge/apigateway for Admin Node Manager and API Gateway containers, and /merge/analytics for API Gateway Analytics containers.

docker run -v /tmp/apigateway:/merge/apigateway --name=anm ...
docker run -v /tmp/analytics:/merge/analytics --name=analytics ...
Last modified December 10, 2019: restructure apig docker topics for cms (3fbbde7f)