序
本文主要研究下springboot2的micrometer
micrometer
springboot2在spring-boot-actuator中引入了micrometer，对1.x的metrics进行了重构，另外支持对接的监控系统也更加丰富(Atlas、Datadog、Ganglia、Graphite、Influx、JMX、NewRelic、Prometheus、SignalFx、StatsD、Wavefront)。1.x的metrics都有点对齐dropwizard-metrics的味道，而micrometer除了一些基本metrics与dropwizard-metrics相类似外，重点支持了tag。这是一个很重要的信号，标志着老一代的statsd、graphite逐步让步于支持tag的influx以及prometheus。
etsy原版的statsd是不支持tag的，不过datadog以及influx都有对statsd进行改良以支持tag。而influxdb以及prometheus则是天生支持tag的。
对比
- dropwizard-metrics guage
final Gauge sizeGauge = new Gauge() {
@Override
public Long getValue() {
return bufferPoolMXBean.getCount();
}
}; - micrometer
Gauge gauge = Gauge
.builder("gauge", myObj, myObj::gaugeValue)
.description("a description of what this gauge does") // optional
.tags("region", "test") // optional
.register(registry);可以看到micrometer支持tag
metrics tag/label
关于metrics是否支持tag/label，则代表其metrics是否能够有多维度的支持。像statsd不支持tag，如果要区分多host的同一个jvm指标，则通常是通过添加prefix来解决，不过这个给查询统计以及后续扩展带了诸多的不变。
支持tag的好处就是可以进行多维度的统计和查询，以同一微服务但是不同实例的jvm指标来说，可以通过tag来添加host标识，这样监控系统就可以灵活根据tag查询过滤来查看不同主机粒度的，甚至是不同数据中心的粒度。
Prometheus
springboot2启用/actuator/prometheus端点，供Prometheus来抓取指标。
maven
org.springframework.boot
spring-boot-starter-actuator
io.micrometer
micrometer-registry-prometheus
配置
management.endpoints.web.exposure.include=*/actuator/prometheus
# HELP process_cpu_usage The "recent cpu usage" for the Java Virtual Machine process
# TYPE process_cpu_usage gauge
process_cpu_usage 0.0
# HELP tomcat_global_request_seconds
# TYPE tomcat_global_request_seconds summary
tomcat_global_request_seconds_count{name="http-nio-8080",} 2.0
tomcat_global_request_seconds_sum{name="http-nio-8080",} 0.111
# HELP tomcat_global_received_bytes_total
# TYPE tomcat_global_received_bytes_total counter
tomcat_global_received_bytes_total{name="http-nio-8080",} 0.0
# HELP jvm_buffer_count An estimate of the number of buffers in the pool
# TYPE jvm_buffer_count gauge
jvm_buffer_count{id="mapped",} 0.0
jvm_buffer_count{id="direct",} 4.0
# HELP jvm_threads_live The current number of live threads including both daemon and non-daemon threads
# TYPE jvm_threads_live gauge
jvm_threads_live 43.0
# HELP process_files_open The open file descriptor count
# TYPE process_files_open gauge
process_files_open 84.0
# HELP tomcat_threads_current
# TYPE tomcat_threads_current gauge
tomcat_threads_current{name="http-nio-8080",} 10.0
# HELP tomcat_servlet_error_total
# TYPE tomcat_servlet_error_total counter
tomcat_servlet_error_total{name="default",} 0.0
# HELP process_start_time_seconds The start time of the Java virtual machine
# TYPE process_start_time_seconds gauge
process_start_time_seconds 1.521297826521E9
# HELP tomcat_sessions_active_max
# TYPE tomcat_sessions_active_max gauge
tomcat_sessions_active_max 0.0
# HELP tomcat_servlet_request_max_seconds
# TYPE tomcat_servlet_request_max_seconds gauge
tomcat_servlet_request_max_seconds{name="default",} 0.0
# HELP jvm_memory_used_bytes The amount of used memory
# TYPE jvm_memory_used_bytes gauge
jvm_memory_used_bytes{area="nonheap",id="CodeHeap 'non-nmethods'",} 3073408.0
jvm_memory_used_bytes{area="nonheap",id="Metaspace",} 4.2002072E7
jvm_memory_used_bytes{area="nonheap",id="Compressed Class Space",} 5467256.0
jvm_memory_used_bytes{area="heap",id="G1 Eden Space",} 1.05906176E8
jvm_memory_used_bytes{area="heap",id="G1 Old Gen",} 1.8914304E7
jvm_memory_used_bytes{area="heap",id="G1 Survivor Space",} 1.048576E7
jvm_memory_used_bytes{area="nonheap",id="CodeHeap 'non-profiled nmethods'",} 9643520.0
# HELP tomcat_sessions_rejected_total
# TYPE tomcat_sessions_rejected_total counter
tomcat_sessions_rejected_total 0.0
# HELP system_load_average_1m The sum of the number of runnable entities queued to available processors and the number of runnable entities running on the available processors averaged over a period of time
# TYPE system_load_average_1m gauge
system_load_average_1m 3.796875
# HELP tomcat_threads_config_max
# TYPE tomcat_threads_config_max gauge
tomcat_threads_config_max{name="http-nio-8080",} 200.0
# HELP tomcat_cache_hit_total
# TYPE tomcat_cache_hit_total counter
tomcat_cache_hit_total 0.0
# HELP tomcat_sessions_active_current
# TYPE tomcat_sessions_active_current gauge
tomcat_sessions_active_current 0.0
# HELP jvm_gc_pause_seconds Time spent in GC pause
# TYPE jvm_gc_pause_seconds summary
jvm_gc_pause_seconds_count{action="end of minor GC",cause="Metadata GC Threshold",} 1.0
jvm_gc_pause_seconds_sum{action="end of minor GC",cause="Metadata GC Threshold",} 0.017
jvm_gc_pause_seconds_max{action="end of minor GC",cause="Metadata GC Threshold",} 0.017
jvm_gc_pause_seconds_count{action="end of minor GC",cause="G1 Evacuation Pause",} 1.0
jvm_gc_pause_seconds_sum{action="end of minor GC",cause="G1 Evacuation Pause",} 0.019
jvm_gc_pause_seconds_max{action="end of minor GC",cause="G1 Evacuation Pause",} 0.019
# HELP logback_events_total Number of error level events that made it to the logs
# TYPE logback_events_total counter
logback_events_total{level="error",} 0.0
logback_events_total{level="warn",} 0.0
logback_events_total{level="info",} 39.0
logback_events_total{level="debug",} 0.0
logback_events_total{level="trace",} 0.0
# HELP jvm_gc_memory_promoted_bytes_total Count of positive increases in the size of the old generation memory pool before GC to after GC
# TYPE jvm_gc_memory_promoted_bytes_total counter
jvm_gc_memory_promoted_bytes_total 0.0
# HELP jvm_buffer_total_capacity_bytes An estimate of the total capacity of the buffers in this pool
# TYPE jvm_buffer_total_capacity_bytes gauge
jvm_buffer_total_capacity_bytes{id="mapped",} 0.0
jvm_buffer_total_capacity_bytes{id="direct",} 32768.0
# HELP jvm_classes_loaded The number of classes that are currently loaded in the Java virtual machine
# TYPE jvm_classes_loaded gauge
jvm_classes_loaded 8219.0
# HELP jvm_classes_unloaded_total The total number of classes unloaded since the Java virtual machine has started execution
# TYPE jvm_classes_unloaded_total counter
jvm_classes_unloaded_total 0.0
# HELP tomcat_sessions_alive_max_seconds
# TYPE tomcat_sessions_alive_max_seconds gauge
tomcat_sessions_alive_max_seconds 0.0
# HELP jvm_gc_max_data_size_bytes Max size of old generation memory pool
# TYPE jvm_gc_max_data_size_bytes gauge
jvm_gc_max_data_size_bytes -1.0
# HELP tomcat_sessions_created_total
# TYPE tomcat_sessions_created_total counter
tomcat_sessions_created_total 0.0
# HELP system_cpu_usage The "recent cpu usage" for the whole system
# TYPE system_cpu_usage gauge
system_cpu_usage 0.0
# HELP jvm_threads_daemon The current number of live daemon threads
# TYPE jvm_threads_daemon gauge
jvm_threads_daemon 41.0
# HELP system_cpu_count The number of processors available to the Java virtual machine
# TYPE system_cpu_count gauge
system_cpu_count 8.0
# HELP jvm_memory_max_bytes The maximum amount of memory in bytes that can be used for memory management
# TYPE jvm_memory_max_bytes gauge
jvm_memory_max_bytes{area="nonheap",id="CodeHeap 'non-nmethods'",} 7553024.0
jvm_memory_max_bytes{area="nonheap",id="Metaspace",} -1.0
jvm_memory_max_bytes{area="nonheap",id="Compressed Class Space",} 1.073741824E9
jvm_memory_max_bytes{area="heap",id="G1 Eden Space",} -1.0
jvm_memory_max_bytes{area="heap",id="G1 Old Gen",} 4.294967296E9
jvm_memory_max_bytes{area="heap",id="G1 Survivor Space",} -1.0
jvm_memory_max_bytes{area="nonheap",id="CodeHeap 'non-profiled nmethods'",} 2.44105216E8
# HELP tomcat_sessions_expired_total
# TYPE tomcat_sessions_expired_total counter
tomcat_sessions_expired_total 0.0
# HELP tomcat_global_sent_bytes_total
# TYPE tomcat_global_sent_bytes_total counter
tomcat_global_sent_bytes_total{name="http-nio-8080",} 2524.0
# HELP tomcat_global_error_total
# TYPE tomcat_global_error_total counter
tomcat_global_error_total{name="http-nio-8080",} 0.0
# HELP process_files_max The maximum file descriptor count
# TYPE process_files_max gauge
process_files_max 10240.0
# HELP jvm_gc_live_data_size_bytes Size of old generation memory pool after a full GC
# TYPE jvm_gc_live_data_size_bytes gauge
jvm_gc_live_data_size_bytes 0.0
# HELP jvm_gc_memory_allocated_bytes_total Incremented for an increase in the size of the young generation memory pool after one GC to before the next
# TYPE jvm_gc_memory_allocated_bytes_total counter
jvm_gc_memory_allocated_bytes_total 4977768.0
# HELP tomcat_threads_busy
# TYPE tomcat_threads_busy gauge
tomcat_threads_busy{name="http-nio-8080",} 1.0
# HELP jvm_memory_committed_bytes The amount of memory in bytes that is committed for the Java virtual machine to use
# TYPE jvm_memory_committed_bytes gauge
jvm_memory_committed_bytes{area="nonheap",id="CodeHeap 'non-nmethods'",} 3080192.0
jvm_memory_committed_bytes{area="nonheap",id="Metaspace",} 4.5088768E7
jvm_memory_committed_bytes{area="nonheap",id="Compressed Class Space",} 6029312.0
jvm_memory_committed_bytes{area="heap",id="G1 Eden Space",} 1.92937984E8
jvm_memory_committed_bytes{area="heap",id="G1 Old Gen",} 1.19537664E8
jvm_memory_committed_bytes{area="heap",id="G1 Survivor Space",} 1.048576E7
jvm_memory_committed_bytes{area="nonheap",id="CodeHeap 'non-profiled nmethods'",} 9699328.0
# HELP jvm_threads_peak The peak live thread count since the Java virtual machine started or peak was reset
# TYPE jvm_threads_peak gauge
jvm_threads_peak 49.0
# HELP http_server_requests_seconds
# TYPE http_server_requests_seconds summary
http_server_requests_seconds_count{exception="None",method="GET",status="200",uri="/actuator",} 1.0
http_server_requests_seconds_sum{exception="None",method="GET",status="200",uri="/actuator",} 0.046773049
http_server_requests_seconds_max{exception="None",method="GET",status="200",uri="/actuator",} 0.046773049
http_server_requests_seconds_count{exception="None",method="GET",status="200",uri="/**/favicon.ico",} 1.0
http_server_requests_seconds_sum{exception="None",method="GET",status="200",uri="/**/favicon.ico",} 0.020588395
http_server_requests_seconds_max{exception="None",method="GET",status="200",uri="/**/favicon.ico",} 0.020588395
# HELP jvm_buffer_memory_used_bytes An estimate of the memory that the Java virtual machine is using for this buffer pool
# TYPE jvm_buffer_memory_used_bytes gauge
jvm_buffer_memory_used_bytes{id="mapped",} 0.0
jvm_buffer_memory_used_bytes{id="direct",} 32768.0
# HELP tomcat_global_request_max_seconds
# TYPE tomcat_global_request_max_seconds gauge
tomcat_global_request_max_seconds{name="http-nio-8080",} 0.087
# HELP tomcat_cache_access_total
# TYPE tomcat_cache_access_total counter
tomcat_cache_access_total 0.0
# HELP tomcat_servlet_request_seconds
# TYPE tomcat_servlet_request_seconds summary
tomcat_servlet_request_seconds_count{name="default",} 0.0
tomcat_servlet_request_seconds_sum{name="default",} 0.0
# HELP process_uptime_seconds The uptime of the Java virtual machine
# TYPE process_uptime_seconds gauge
process_uptime_seconds 14.232比如jvm_memory_used_bytes
jvm_memory_used_bytes{area="nonheap",id="CodeHeap 'non-nmethods'",} 3073408.0
jvm_memory_used_bytes{area="nonheap",id="Metaspace",} 4.2002072E7
jvm_memory_used_bytes{area="nonheap",id="Compressed Class Space",} 5467256.0
jvm_memory_used_bytes{area="heap",id="G1 Eden Space",} 1.05906176E8
jvm_memory_used_bytes{area="heap",id="G1 Old Gen",} 1.8914304E7
jvm_memory_used_bytes{area="heap",id="G1 Survivor Space",} 1.048576E7
jvm_memory_used_bytes{area="nonheap",id="CodeHeap 'non-profiled nmethods'",} 9643520.0括号里头的就tag/label，查询的时候就可以使用jvm_memory_used_bytes或者jvm_memory_used_bytes{area="nonheap"}或者jvm_memory_used_bytes{area="nonheap",id="Metaspace"}等配合tag/label进行查询。
小结
springboot2的micrometer支持了tag/label，配合支持tag/label的监控系统，使得我们可以更加方便地对metrics进行多维度的统计查询及监控。
doc
- metrics.dropwizard
- Support for Statsd Tags/Dimensions #1536
- Getting Started with Sending StatsD Metrics to Telegraf & InfluxDB
- How can I send multiple tags in statsd #567
- Using Prometheus in Grafana
- prometheus QUERY EXAMPLES
- Using Micrometer With Spring Boot 2
- Micrometer: Spring Boot 2's new application metrics collector