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85 lines
1.5 KiB
Markdown
85 lines
1.5 KiB
Markdown
---
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id: expvar
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title: ExpVar
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---
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Expvar middleware for [Fiber](https://github.com/gofiber/fiber) that serves via its HTTP server runtime exposed variants in the JSON format. The package is typically only imported for the side effect of registering its HTTP handlers. The handled path is `/debug/vars`.
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## Signatures
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```go
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func New() fiber.Handler
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```
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## Example
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Import the expvar package that is part of the Fiber web framework
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```go
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package main
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import (
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"expvar"
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"fmt"
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"github.com/gofiber/fiber/v2"
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expvarmw "github.com/gofiber/fiber/v2/middleware/expvar"
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)
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var count = expvar.NewInt("count")
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func main() {
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app := fiber.New()
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app.Use(expvarmw.New())
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app.Get("/", func(c *fiber.Ctx) error {
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count.Add(1)
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return c.SendString(fmt.Sprintf("hello expvar count %d", count.Value()))
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})
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fmt.Println(app.Listen(":3000"))
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}
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```
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Visit path `/debug/vars` to see all vars and use query `r=key` to filter exposed variables.
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```bash
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curl 127.0.0.1:3000
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hello expvar count 1
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curl 127.0.0.1:3000/debug/vars
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{
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"cmdline": ["xxx"],
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"count": 1,
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"expvarHandlerCalls": 33,
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"expvarRegexpErrors": 0,
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"memstats": {...}
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}
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curl 127.0.0.1:3000/debug/vars?r=c
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{
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"cmdline": ["xxx"],
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"count": 1
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}
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```
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## Config
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```go
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// Config defines the config for middleware.
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type Config struct {
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// Next defines a function to skip this middleware when returned true.
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//
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// Optional. Default: nil
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Next func(c *fiber.Ctx) bool
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}
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```
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## Default Config
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```go
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var ConfigDefault = Config{
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Next: nil,
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}
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```
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