sbus-router

A configurable router for Azure Service Bus

Configuration

All configuration is set in environment variables. There must also be at least one rule configured (see below).

Environment Variable	Required	Default	Description
LOG_LEVEL		WARN	The log level for the router.
ROUTER_DLQ_TOPIC	Yes		The name of a topic to route messages that no rules match.
ROUTER_SOURCE_CONNECTION_STRING	Yes		The connection string for the source Service Bus namespace.

Rules

Rules are configured as JSON, the format of which must match the schema provided in rule-schema.json. Please note that in the JSON, one can input fields in the format $ENV_VAR indicating that the field name ENV_VAR is to be replaced with an environment variable of that name. For example configuration, see the router service in tests/resources/docker-compose.yaml.

The configurable fields for rules are:

• destination_namespaces: The namespaces (comma separated) to which data will be sent. If comma separated, they must match the destination_topics definition.
• destination_topics: The topics (comma separated) to which data will be sent. If this is blank ("") then messages that match the rule will be considered valid, not be produced onto the DLQ, but will be dropped. Topics can be comma separated which means that the messages that match the rule will be sent to each of the topics.
• jmespath: A JMESPath expression to query an element within the JSON contained in the message.
• regexp: A regular expression that will me used to match against the data returned from jmespath.
• source_subscription: The subscription from which data will be retrieved.
• source_topic: The topic from which data will be retrieved.

Please note that environment variables containing rules must be prefixed with ROUTER_RULE_ (e.g. ROUTER_RULE_COUNTRY_GB) and matching against the rules will be done one by one in the alphabetical order of the environment variable name.

Destination Namespaces

Destination namespaces are defined with a prefix of ROUTER_NAMESPACE_ and a suffix of _CONNECTION_STRING. For example, if an environment variable called ROUTER_NAMESPACE_IE_CONNECTION_STRING is set, then a destination namespace of IE can be referred to in the rules.