113 lines
4.8 KiB
Go
113 lines
4.8 KiB
Go
// Package metrics implements Prometheus-compatible metrics for applications.
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//
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// This package is lightweight alternative to https://github.com/prometheus/client_golang
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// with simpler API and smaller dependencies.
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//
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// Usage:
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//
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// 1. Register the required metrics via New* functions.
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// 2. Expose them to `/metrics` page via WritePrometheus.
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// 3. Update the registered metrics during application lifetime.
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//
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// The package has been extracted from https://victoriametrics.com/
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package metrics
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import (
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"io"
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)
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type namedMetric struct {
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name string
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metric metric
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}
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type metric interface {
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marshalTo(prefix string, w io.Writer)
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}
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var defaultSet = NewSet()
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// WritePrometheus writes all the registered metrics in Prometheus format to w.
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//
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// If exposeProcessMetrics is true, then various `go_*` and `process_*` metrics
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// are exposed for the current process.
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//
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// The WritePrometheus func is usually called inside "/metrics" handler:
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//
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// http.HandleFunc("/metrics", func(w http.ResponseWriter, req *http.Request) {
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// metrics.WritePrometheus(w, true)
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// })
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//
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func WritePrometheus(w io.Writer, exposeProcessMetrics bool) {
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defaultSet.WritePrometheus(w)
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if exposeProcessMetrics {
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WriteProcessMetrics(w)
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}
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}
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// WriteProcessMetrics writes additional process metrics in Prometheus format to w.
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//
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// The following `go_*` and `process_*` metrics are exposed for the currently
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// running process. Below is a short description for the exposed `process_*` metrics:
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//
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// - process_cpu_seconds_system_total - CPU time spent in syscalls
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// - process_cpu_seconds_user_total - CPU time spent in userspace
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// - process_cpu_seconds_total - CPU time spent by the process
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// - process_major_pagefaults_total - page faults resulted in disk IO
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// - process_minor_pagefaults_total - page faults resolved without disk IO
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// - process_resident_memory_bytes - recently accessed memory (aka RSS or resident memory)
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// - process_resident_memory_peak_bytes - the maximum RSS memory usage
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// - process_resident_memory_anon_bytes - RSS for memory-mapped files
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// - process_resident_memory_file_bytes - RSS for memory allocated by the process
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// - process_resident_memory_shared_bytes - RSS for memory shared between multiple processes
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// - process_virtual_memory_bytes - virtual memory usage
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// - process_virtual_memory_peak_bytes - the maximum virtual memory usage
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// - process_num_threads - the number of threads
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// - process_start_time_seconds - process start time as unix timestamp
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//
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// - process_io_read_bytes_total - the number of bytes read via syscalls
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// - process_io_written_bytes_total - the number of bytes written via syscalls
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// - process_io_read_syscalls_total - the number of read syscalls
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// - process_io_write_syscalls_total - the number of write syscalls
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// - process_io_storage_read_bytes_total - the number of bytes actually read from disk
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// - process_io_storage_written_bytes_total - the number of bytes actually written to disk
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//
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// - go_memstats_alloc_bytes - memory usage for Go objects in the heap
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// - go_memstats_alloc_bytes_total - the cumulative counter for total size of allocated Go objects
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// - go_memstats_frees_total - the cumulative counter for number of freed Go objects
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// - go_memstats_gc_cpu_fraction - the fraction of CPU spent in Go garbage collector
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// - go_memstats_gc_sys_bytes - the size of Go garbage collector metadata
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// - go_memstats_heap_alloc_bytes - the same as go_memstats_alloc_bytes
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// - go_memstats_heap_idle_bytes - idle memory ready for new Go object allocations
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// - go_memstats_heap_objects - the number of Go objects in the heap
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// - go_memstats_heap_sys_bytes - memory requested for Go objects from the OS
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// - go_memstats_mallocs_total - the number of allocations for Go objects
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// - go_memstats_next_gc_bytes - the target heap size when the next garbage collection should start
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// - go_memstats_stack_inuse_bytes - memory used for goroutine stacks
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// - go_memstats_stack_sys_bytes - memory requested fromthe OS for goroutine stacks
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// - go_memstats_sys_bytes - memory requested by Go runtime from the OS
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//
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// The WriteProcessMetrics func is usually called in combination with writing Set metrics
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// inside "/metrics" handler:
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//
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// http.HandleFunc("/metrics", func(w http.ResponseWriter, req *http.Request) {
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// mySet.WritePrometheus(w)
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// metrics.WriteProcessMetrics(w)
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// })
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//
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// See also WrteFDMetrics.
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func WriteProcessMetrics(w io.Writer) {
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writeGoMetrics(w)
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writeProcessMetrics(w)
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}
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// WriteFDMetrics writes `process_max_fds` and `process_open_fds` metrics to w.
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func WriteFDMetrics(w io.Writer) {
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writeFDMetrics(w)
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}
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// UnregisterMetric removes metric with the given name from default set.
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func UnregisterMetric(name string) bool {
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return defaultSet.UnregisterMetric(name)
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}
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