# README
Ginprom
Gin Prometheus metrics exporter
Inspired by github.com/zsais/go-gin-prometheus
Install
Simply run:
go get -u github.com/Depado/ginprom
Differences with go-gin-prometheus
- No support for Prometheus' Push Gateway
- Options on constructor
- Adds a
pathlabel to get the matched route - Ability to ignore routes
Usage
package main
import (
"github.com/Depado/ginprom"
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Subsystem("gin"),
ginprom.Path("/metrics"),
)
r.Use(p.Instrument())
r.GET("/hello/:id", func(c *gin.Context) {})
r.GET("/world/:id", func(c *gin.Context) {})
r.Run("127.0.0.1:8080")
}
Options
Custom counters
Add custom counters to add own values to the metrics
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
)
p.AddCustomCounter("custom", "Some help text to provide", []string{"label"})
r.Use(p.Instrument())
Save p and use the following functions:
- IncrementCounterValue
- AddCounterValue
Custom gauges
Add custom gauges to add own values to the metrics
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
)
p.AddCustomGauge("custom", "Some help text to provide", []string{"label"})
r.Use(p.Instrument())
Save p and use the following functions:
- IncrementGaugeValue
- DecrementGaugeValue
- SetGaugeValue
Custom histograms
Add custom histograms to add own values to the metrics
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
)
p.AddCustomHistogram("internal_request_latency", "Duration of internal HTTP requests", []string{"url", "method", "status"})
r.Use(p.Instrument())
Save p and use the following functions:
- AddCustomHistogramValue
Path
Override the default path (/metrics) on which the metrics can be accessed:
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Path("/custom/metrics"),
)
r.Use(p.Instrument())
Namespace
Override the default namespace (gin):
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Namespace("custom_ns"),
)
r.Use(p.Instrument())
Subsystem
Override the default (gonic) subsystem:
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Subsystem("your_subsystem"),
)
r.Use(p.Instrument())
Engine
The preferred way to pass the router to ginprom:
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
)
r.Use(p.Instrument())
The alternative being to call the Use method after initialization:
p := ginprom.New()
// ...
r := gin.New()
p.Use(r)
r.Use(p.Instrument())
Prometheus Registry
Use a custom prometheus.Registry instead of prometheus client's global registry. This option allows
to use ginprom in multiple gin engines in the same process, or if you would like to integrate ginprom with your own
prometheus Registry.
registry := prometheus.NewRegistry() // creates new prometheus metric registry
r := gin.New()
p := ginprom.New(
ginprom.Registry(registry),
)
r.Use(p.Instrument())
HandlerNameFunc
Change the way the handler label is computed. By default, the (*gin.Context).HandlerName
function is used.
This option is useful when wanting to group different functions under
the same handler label or when using gin with decorated handlers.
r := gin.Default()
p := ginprom.New(
HandlerNameFunc(func (c *gin.Context) string {
return "my handler"
}),
)
r.Use(p.Instrument())
RequestPathFunc
Change how the path label is computed. By default, the (*gin.Context).FullPath function
is used.
This option is useful when wanting to group different requests under the same path
label or when wanting to process unknown routes (the default (*gin.Context).FullPath returns
an empty string for unregistered routes). Note that requests for which f returns the empty
string are ignored.
To specifically ignore certain paths, see the Ignore option.
r := gin.Default()
p := ginprom.New(
// record a metric for unregistered routes under the path label "<unknown>"
RequestPathFunc(func (c *gin.Context) string {
if fullpath := c.FullPath(); fullpath != "" {
return fullpath
}
return "<unknown>"
}),
)
r.Use(p.Instrument())
CustomCounterLabels
Add custom labels to the counter metric.
r := gin.Default()
p := ginprom.New(
ginprom.CustomCounterLabels([]string{"client_id"}, func(c *gin.Context) map[string]string {
client_id := c.GetHeader("x-client-id")
if client_id == "" {
client_id = "unknown"
}
return map[string]string{"client_id": client_id}
}),
)
r.Use(p.Instrument())
Ignore
Ignore allows to completely ignore some routes. Even though you can apply the middleware to the only groups you're interested in, it is sometimes useful to have routes not instrumented.
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Ignore("/api/no/no/no", "/api/super/secret/route")
)
r.Use(p.Instrument())
Note that most of the time this can be solved by gin groups:
r := gin.New()
p := ginprom.New(ginprom.Engine(r))
// Add the routes that do not need instrumentation
g := r.Group("/api/")
g.Use(p.Instrument())
{
// Instrumented routes
}
Token
Specify a secret token which Prometheus will use to access the endpoint. If the token is invalid, the endpoint will return an error.
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
ginprom.Token("supersecrettoken")
)
r.Use(p.Instrument())
Bucket size
Specify the bucket size for the request duration histogram according to your expected durations.
r := gin.New()
p := ginprom.New(
ginprom.Engine(r),
ginprom.BucketSize([]float64{.005, .01, .025, .05, .1, .25, .5, 1, 2.5, 5, 10}),
)
r.Use(p.Instrument())
Troubleshooting
The instrumentation doesn't seem to work
Make sure you have set the gin.Engine in the ginprom middleware, either when
initializing it using ginprom.New(ginprom.Engine(r)) or using the Use
function after the initialization like this :
p := ginprom.New(
ginprom.Namespace("gin"),
ginprom.Subsystem("gonic"),
ginprom.Path("/metrics"),
)
p.Use(r)
r.Use(p.Instrument())
By design, if the middleware was to panic, it would do so when a route is called. That's why it just silently fails when no engine has been set.