mirror of https://github.com/divan/expvarmon.git
122 lines
4.7 KiB
Markdown
122 lines
4.7 KiB
Markdown
# ExpvarMon
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[](https://drone.io/github.com/divan/expvarmon/latest)
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TermUI based Go apps monitor using [expvars](http://golang.org/pkg/expvar/) variables (/debug/vars). Quickest way to monitor your Go app.
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## Introduction
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Go apps console monitoring tool. Minimal configuration efforts. Quick and easy monitoring solution for one or multiple services.
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## Features
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* Single- and multi-apps mode
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* Local and remote apps support
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* Arbitrary number of apps and vars to monitor (from 1 to 30+, depends on size of your terminal)
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* Track restarted/failed apps
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* Show maximum value
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* Supports: Integer, float, duration, memory, string, bool variables
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* Sparkline charts for integer, duration and memory data
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* Auto-resize on font-size change or window resize
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* Uses amazing [TermUI](https://github.com/gizak/termui) library by [gizak](https://github.com/gizak)
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## Demo
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### Multiple apps mode
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<img src="./demo/demo_multi.png" alt="Multi mode" width="800">
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### Single app mode
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<img src="./demo/demo_single.png" alt="Single mode" width="800">
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You can monitor arbitrary number of services and variables:
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<a href="./demo/demo_1var.png" target="_blank"><img src="./demo/demo_1var.png" alt="1 var" width="350"></a> <a href="./demo/demo_small.png" target="_blank"><img src="./demo/demo_small.png" alt="25 apps" width="350"></a>
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## Purpose
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This app targets debug/develop sessions when you need an instant way to monitor you app(s). It's not intended to monitor apps in production.
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Also it doesn't use any storage engines and doesn't send notifications.
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## Install
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Just run go get:
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go get github.com/divan/expvarmon
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## Usage
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### Prepare your app
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First, you have to add [expvars](http://golang.org/pkg/expvar/) support into your Go program. It's as simple as:
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import _ "expvar"
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and note the port your app is listening on. If it's not, just add two lines:
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import "net/http"
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...
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http.ListenAndServe(":1234", nil)
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and expvar will add handler for "localhost:1234/debug/vars" to your app.
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By default, expvars adds two variables: *memstats* and *cmdline*. It's enough to monitor memory and garbage collector status in your app.
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### Run expvarmon
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Just run expvarmon with -ports="1234" flag:
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expvarmon -ports="1234"
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That's it.
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More examples:
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./expvarmon -ports="80"
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./expvarmon -ports="23000-23010,80" -i=1m
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./expvarmon -ports="80,remoteapp:80" -vars="mem:memstats.Alloc,duration:Response.Mean,Counter"
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./expvarmon -ports="1234-1236" -vars="Goroutines" -self
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## Advanced usage
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If you need to monitor more (or less) vars, you can specify them with -vars command line flag.
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$ expvarmon -help
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Usage of ./expvarmon:
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-dummy=false: Use dummy (console) output
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-i=5s: Polling interval
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-ports="": Ports for accessing services expvars (start-end,port2,port3)
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-self=false: Monitor itself
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-vars="mem:memstats.Alloc,mem:memstats.Sys,mem:memstats.HeapAlloc,mem:memstats.HeapInuse,memstats.EnableGC,memstats.NumGC,duration:memstats.PauseTotalNs": Vars to monitor (comma-separated)
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Examples:
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./expvarmon -ports="80"
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./expvarmon -ports="23000-23010,80" -i=1m
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./expvarmon -ports="80,remoteapp:80" -vars="mem:memstats.Alloc,duration:Response.Mean,Counter"
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./expvarmon -ports="1234-1236" -vars="Goroutines" -self
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For more details and docs, see README: http://github.com/divan/expvarmon
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So, yes, you can specify multiple ports, using '-' for ranges, and specify host(s) for remote apps.
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You can also monitor expvarmon itself, using -self flag.
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### Vars
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Expvarmon doesn't restrict you to monitor only memstats. You can publish your own counters and variables using [expvar.Publish()](http://golang.org/pkg/expvar/#Publish) method or using expvar wrappers libraries. Just pass your variables names as they appear in JSON to -var command line flag.
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Notation is dot-separated, for example: **memstats.Alloc** for .MemStats.Alloc field. Quick link to runtime.MemStats documentation: http://golang.org/pkg/runtime/#MemStats
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Expvar allows to export only basic types - structs, ints, floats, bools and strings. Ints are used for sparklines, and displayed as is. But you can specify modifier to make sure it will be rendered properly.
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Vars are specified as a comma-separated list of var identifiers with (optional) modifiers.
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| Modifier | Description |
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| --------- | ----------- |
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| mem: | renders int64 as memory string (KB, MB, etc) |
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| duration: | renders int64 as time.Duration (1s, 2ms, 12h23h) |
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| str: | doesn't display sparklines chart for this value, just display as string |
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## TODO
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* ports auto-discovery for given hostname
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* more tests coverage
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* better usage of color highlighting (for max values or failed apps), after relevant patches will be merged to TermUI
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