As for all other endpoints in Gerrit, some metrics are automatically emitted when the /config/server/healthcheck~status endpoint is hit (thanks to the Dropwizard library). For example, some of the metrics exposed will be:
# HELP http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint Generated from Dropwizard metric import (metric=http/server/rest_api/response_bytes/healthcheck-com.googlesource.gerrit.plugins.healthcheck.api.HealthCheckStatusEndpoint, type=com.codahale.metrics.Histogram)
# TYPE http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint summary
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.5",} 308.0
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.75",} 308.0
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.95",} 308.0
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.98",} 310.0
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.99",} 310.0
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.999",} 310.0
http_server_rest_api_response_bytes_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_count 4.0
# HELP http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint Generated from Dropwizard metric import (metric=http/server/rest_api/server_latency/healthcheck-com.googlesource.gerrit.plugins.healthcheck.api.HealthCheckStatusEndpoint, type=com.codahale.metrics.Timer)
# TYPE http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint summary
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.5",} 0.008638662
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.75",} 0.008638662
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.95",} 0.010553707
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.98",} 0.147902061
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.99",} 0.147902061
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint{quantile="0.999",} 0.147902061
http_server_rest_api_server_latency_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_count 4.0
# HELP http_server_rest_api_count_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_total Generated from Dropwizard metric import (metric=http/server/rest_api/count/healthcheck-com.googlesource.gerrit.plugins.healthcheck.api.HealthCheckStatusEndpoint, type=com.codahale.metrics.Meter)
# TYPE http_server_rest_api_count_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_total counter
http_server_rest_api_count_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_total 4.0
# HELP http_server_rest_api_error_count_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_500_total Generated from Dropwizard metric import (metric=http/server/rest_api/error_count/healthcheck-com.googlesource.gerrit.plugins.healthcheck.api.HealthCheckStatusEndpoint/500, type=com.codahale.metrics.Meter)
# TYPE http_server_rest_api_error_count_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_500_total counter
http_server_rest_api_error_count_healthcheck_com_googlesource_gerrit_plugins_healthcheck_api_HealthCheckStatusEndpoint_500_total 2.0
However some extra metrics are also emitted to expose more details about the healthcheck result. Specifically two metrics are emitted for each component contributing to the overall healthcheck result (JGIT, PROJECTLIST, REVIEWDB).
# HELP plugins_healthcheck_jgit_latency Generated from Dropwizard metric import (metric=plugins/healthcheck/jgit/latency, type=com.codahale.metrics.Timer)
# TYPE plugins_healthcheck_jgit_latency summary
plugins_healthcheck_jgit_latency{quantile="0.5",} 0.002
plugins_healthcheck_jgit_latency{quantile="0.75",} 0.002
plugins_healthcheck_jgit_latency{quantile="0.95",} 0.002
plugins_healthcheck_jgit_latency{quantile="0.98",} 0.002
plugins_healthcheck_jgit_latency{quantile="0.99",} 0.002
plugins_healthcheck_jgit_latency{quantile="0.999",} 0.002
plugins_healthcheck_jgit_latency_count 1.0
# HELP plugins_healthcheck_projectslist_latency Generated from Dropwizard metric import (metric=plugins/healthcheck/projectslist/latency, type=com.codahale.metrics.Timer)
# TYPE plugins_healthcheck_projectslist_latency summary
plugins_healthcheck_projectslist_latency{quantile="0.5",} 0.001
plugins_healthcheck_projectslist_latency{quantile="0.75",} 0.001
plugins_healthcheck_projectslist_latency{quantile="0.95",} 0.001
plugins_healthcheck_projectslist_latency{quantile="0.98",} 0.001
plugins_healthcheck_projectslist_latency{quantile="0.99",} 0.001
plugins_healthcheck_projectslist_latency{quantile="0.999",} 0.001
plugins_healthcheck_projectslist_latency_count 1.0
# HELP plugins_healthcheck_reviewdb_latency Generated from Dropwizard metric import (metric=plugins/healthcheck/reviewdb/latency, type=com.codahale.metrics.Timer)
# TYPE plugins_healthcheck_reviewdb_latency summary
plugins_healthcheck_reviewdb_latency{quantile="0.5",} 0.001
plugins_healthcheck_reviewdb_latency{quantile="0.75",} 0.001
plugins_healthcheck_reviewdb_latency{quantile="0.95",} 0.001
plugins_healthcheck_reviewdb_latency{quantile="0.98",} 0.001
plugins_healthcheck_reviewdb_latency{quantile="0.99",} 0.001
plugins_healthcheck_reviewdb_latency{quantile="0.999",} 0.001
plugins_healthcheck_reviewdb_latency_count 1.0
# HELP plugins_healthcheck_jgit_failure_total Generated from Dropwizard metric import (metric=plugins/healthcheck/jgit/failure, type=com.codahale.metrics.Meter)
# TYPE plugins_healthcheck_jgit_failure_total counter
plugins_healthcheck_jgit_failure_total 0.0
# HELP plugins_healthcheck_projectslist_failure_total Generated from Dropwizard metric import (metric=plugins/healthcheck/projectslist/failure, type=com.codahale.metrics.Meter)
# TYPE plugins_healthcheck_projectslist_failure_total counter
plugins_healthcheck_projectslist_failure_total 0.0
# HELP plugins_healthcheck_reviewdb_failure_total Generated from Dropwizard metric import (metric=plugins/healthcheck/reviewdb/failure, type=com.codahale.metrics.Meter)
# TYPE plugins_healthcheck_reviewdb_failure_total counter
plugins_healthcheck_reviewdb_failure_total 0.0
Metrics will be exposed to prometheus by the metrics-reporter-prometheus plugin.