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new prometheus middleware
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,154 @@ | ||
| # Usage | ||
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| ``` | ||
| package main | ||
| import ( | ||
| "github.com/labstack/echo/v4" | ||
| "github.com/labstack/echo-contrib/prometheus/echoprometheus" | ||
| ) | ||
| func main() { | ||
| e := echo.New() | ||
| // Enable metrics middleware | ||
| e.Use(echoprometheus.NewMiddleware("myapp")) | ||
| e.GET("/metrics", echoprometheus.NewHandler()) | ||
| e.Logger.Fatal(e.Start(":1323")) | ||
| } | ||
| ``` | ||
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| # How to migrate | ||
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| ## Creating and adding middleware to the application | ||
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| Older `prometheus` middleware | ||
| ```go | ||
| e := echo.New() | ||
| p := prometheus.NewPrometheus("echo", nil) | ||
| p.Use(e) | ||
| ``` | ||
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| With the new `echoprometheus` middleware | ||
| ```go | ||
| e := echo.New() | ||
| e.Use(echoprometheus.NewMiddleware("myapp")) // register middleware to gather metrics from requests | ||
| e.GET("/metrics", echoprometheus.NewHandler()) // register route to serve gathered metrics in Prometheus format | ||
| ``` | ||
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| ## Replacement for `Prometheus.MetricsList` field, `NewMetric(m *Metric, subsystem string)` function and `prometheus.Metric` struct | ||
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| The `NewMetric` function allowed to create custom metrics with the old `prometheus` middleware. This helper is no longer available | ||
| to avoid the added complexity. It is recommended to use native Prometheus metrics and register those yourself. | ||
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| This can be done now as follows: | ||
| ```go | ||
| e := echo.New() | ||
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| customRegistry := prometheus.NewRegistry() // create custom registry for your custom metrics | ||
| customCounter := prometheus.NewCounter( // create new counter metric. This is replacement for `prometheus.Metric` struct | ||
| prometheus.CounterOpts{ | ||
| Name: "custom_requests_total", | ||
| Help: "How many HTTP requests processed, partitioned by status code and HTTP method.", | ||
| }, | ||
| ) | ||
| if err := customRegistry.Register(customCounter); err != nil { // register your new counter metric with metrics registry | ||
| log.Fatal(err) | ||
| } | ||
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| e.Use(NewMiddlewareWithConfig(MiddlewareConfig{ | ||
| AfterNext: func(c echo.Context, err error) { | ||
| customCounter.Inc() // use our custom metric in middleware. after every request increment the counter | ||
| }, | ||
| Registerer: customRegistry, // use our custom registry instead of default Prometheus registry | ||
| })) | ||
| e.GET("/metrics", NewHandlerWithConfig(HandlerConfig{Gatherer: customRegistry})) // register route for getting gathered metrics data from our custom Registry | ||
| ``` | ||
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| ## Replacement for `Prometheus.MetricsPath` | ||
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| `MetricsPath` was used to skip metrics own route from Prometheus metrics. Skipping is no longer done and requests to Prometheus | ||
| route will be included in gathered metrics. | ||
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| To restore the old behaviour the `/metrics` path needs to be excluded from counting using the Skipper function: | ||
| ```go | ||
| conf := echoprometheus.MiddlewareConfig{ | ||
| Skipper: func(c echo.Context) bool { | ||
| return c.Path() == "/metrics" | ||
| }, | ||
| } | ||
| e.Use(echoprometheus.NewMiddlewareWithConfig(conf)) | ||
| ``` | ||
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| ## Replacement for `Prometheus.RequestCounterURLLabelMappingFunc` and `Prometheus.RequestCounterHostLabelMappingFunc` | ||
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| These function fields were used to define how "URL" or "Host" attribute in Prometheus metric lines are created. | ||
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| These can now be substituted by using `LabelFuncs`: | ||
| ```go | ||
| e.Use(echoprometheus.NewMiddlewareWithConfig(echoprometheus.MiddlewareConfig{ | ||
| LabelFuncs: map[string]echoprometheus.LabelValueFunc{ | ||
| "scheme": func(c echo.Context, err error) string { // additional custom label | ||
| return c.Scheme() | ||
| }, | ||
| "url": func(c echo.Context, err error) string { // overrides default 'url' label value | ||
| return "x_" + c.Request().URL.Path | ||
| }, | ||
| "host": func(c echo.Context, err error) string { // overrides default 'host' label value | ||
| return "y_" + c.Request().Host | ||
| }, | ||
| }, | ||
| })) | ||
| ``` | ||
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| Will produce Prometheus line as | ||
| `echo_request_duration_seconds_count{code="200",host="y_example.com",method="GET",scheme="http",url="x_/ok",scheme="http"} 1` | ||
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| ## Replacement for `Metric.Buckets` and modifying default metrics | ||
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| The `echoprometheus` middleware registers the following metrics by default: | ||
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| * Counter `requests_total` | ||
| * Histogram `request_duration_seconds` | ||
| * Histogram `response_size_bytes` | ||
| * Histogram `request_size_bytes` | ||
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| You can modify their definition before these metrics are registed with `CounterOptsFunc` and `HistogramOptsFunc` callbacks | ||
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| Example: | ||
| ```go | ||
| e.Use(NewMiddlewareWithConfig(MiddlewareConfig{ | ||
| HistogramOptsFunc: func(opts prometheus.HistogramOpts) prometheus.HistogramOpts { | ||
| if opts.Name == "request_duration_seconds" { | ||
| opts.Buckets = []float64{1.0 * bKB, 2.0 * bKB, 5.0 * bKB, 10.0 * bKB, 100 * bKB, 500 * bKB, 1.0 * bMB, 2.5 * bMB, 5.0 * bMB, 10.0 * bMB} | ||
| } | ||
| return opts | ||
| }, | ||
| CounterOptsFunc: func(opts prometheus.CounterOpts) prometheus.CounterOpts { | ||
| if opts.Name == "requests_total" { | ||
| opts.ConstLabels = prometheus.Labels{"my_const": "123"} | ||
| } | ||
| return opts | ||
| }, | ||
| })) | ||
| ``` | ||
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| ## Replacement for `PushGateway` struct and related methods | ||
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| Function `RunPushGatewayGatherer` starts pushing collected metrics and block until context completes or ErrorHandler returns an error. | ||
| This function should be run in separate goroutine. | ||
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| Example: | ||
| ```go | ||
| go func() { | ||
| config := echoprometheus.PushGatewayConfig{ | ||
| PushGatewayURL: "https://host:9080", | ||
| PushInterval: 10 * time.Millisecond, | ||
| } | ||
| if err := echoprometheus.RunPushGatewayGatherer(context.Background(), config); !errors.Is(err, context.Canceled) { | ||
| log.Fatal(err) | ||
| } | ||
| }() | ||
| ``` |
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