jlogging

Simple json logging and recovery middleware for Gin.

Setup

Get jlogging:

go get github.com/RoundRobinHood/jlogging

Add middleware:

// r := gin.New();
r.Use(jlogging.Middleware())

Functionality

Logging

jlogging prints a single log per request, and allows you to add details to it as the request passes through your code. Adding details is done by accessing the jlogging.RequestLog object from your callback's Gin context. It can then be used to attach additional information to the request:

func Login(c *gin.Context) {
    // Get request log
    jrl, exists := c.Get("jrl")
    if !exists {
        log.Printf("jlogging middleware absent.")
        return
    }
    l := jrl.(*jlogging.RequestLog)

    // Get submitted credentials
    var cred struct {
        Username string `json:"username"`
        Pwd      string `json:"password"`
    }
    if err := c.ShouldBindJson(&cred); err != nil {
        c.JSON(400, gin.H{"error": err.Error()})
        l.Printf("Invalid JSON body submitted")
        l.Details["err"] = err
        return
    }

    // ...

Recovery

In the event of a panic, jlogging recovers, sets ResponseStatus to 500, and the error value of jlogging.RequestLog to a panic details object documenting the panic, a stack trace, and the original status (before the panic occurred).

type PanicDetails struct {
	Descriptor  any    `json:"desc"`
	PriorStatus int    `json:"oldStatus"`
	StackTrace  string `json:"stackTrace"`
}

This is then included in the object logged to stdout. Marshal failures are handled incrementally, with object details being removed until a last-resort string is printed with the format:

fmt.Printf("{\"jlog\":\"Could not marshal request log during panic: %s\"}\n", err)