Monitor

The Database Connector exposes an HTTP server that can be used to monitor instance health and metrics.

The server listens on the port defined by the ADBC_HEALTH_ADDRESS configuration option and defaults to port 2259.

Health

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The Database Connector exposes an HTTP endpoint on /health that returns a JSON containing the status of:

  • Connectivity to the Ably service.
  • Connectivity to the PostgreSQL database.
  • Access to the nodes table, determined by executing SELECT 1 FROM nodes.
  • Access to the outbox table, determined by executing SELECT 1 FROM outbox.

Internally, the connector periodically refreshes the health status for each target according to the interval defined by the ADBC_HEALTH_REFRESH_INTERVAL configuration option.

The following is an example of a healthy response from the endpoint:


curl localhost:2259/health
{
   "ably":{
      "status":"up"
   },
   "nodes_table":{
      "status":"up"
   },
   "outbox_table":{
      "status":"up"
   },
   "postgres":{
      "status":"up"
   }
}


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Metrics

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The Database Connector exposes an HTTP endpoint on /metrics that implements a Prometheus metrics endpoint that can be used to monitor the following metrics:

Metric Type Description
ably_pending_acks gauge Number of pending messages waiting to be acknowledged by Ably.
nodes_table_entries gauge Number of entries in the nodes table.
nodes_table_errors counter Number of errors querying the nodes table.
outbox_table_entries gauge Number of entries in the outbox table.
outbox_table_errors counter Number of errors querying the outbox table.
promhttp_metric_handler_errors_total counter Total number of internal errors encountered by the promhttp metric handler.

The following is an example response from the metrics endpoint:


curl localhost:2259/metrics
# HELP ably_pending_acks Number of pending messages waiting to be acknowledged by Ably
# TYPE ably_pending_acks gauge
ably_pending_acks 0
# HELP nodes_table_entries Number of entries in the nodes table
# TYPE nodes_table_entries gauge
nodes_table_entries 1
# HELP nodes_table_errors Number of errors querying the nodes table
# TYPE nodes_table_errors counter
nodes_table_errors 0
# HELP outbox_table_entries Number of entries in the outbox table
# TYPE outbox_table_entries gauge
outbox_table_entries 1
# HELP outbox_table_errors Number of errors querying the outbox table
# TYPE outbox_table_errors counter
outbox_table_errors 0
# HELP promhttp_metric_handler_errors_total Total number of internal errors encountered by the promhttp metric handler.
# TYPE promhttp_metric_handler_errors_total counter
promhttp_metric_handler_errors_total{cause="encoding"} 0
promhttp_metric_handler_errors_total{cause="gathering"} 0


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Health