echo: prevent double gzip in prometheusecho/v0.15.2

2 files changed, 12 insertions, 6 deletions

diff --git a/echo/echo_default.go b/echo/echo_default.go
index aa9e32a..b5602e6 100644
--- a/echo/echo_default.go
+++ b/echo/echo_default.go
@@ -366,14 +366,10 @@ func (w *EchoWrapper) configureRedirects(c *EchoConfig) {
 }
 
 func (w *EchoWrapper) configureCompression(c *EchoConfig) {
-        metricsSkipper := makeMiddlewareSkipper(c.PrometheusConfig)
-
         w.Use(middleware.Decompress())
 
-        // TODO: This mangles responses but only for Accept: */* (browsers). Why?
         w.Use(middleware.GzipWithConfig(middleware.GzipConfig{
-                Skipper: metricsSkipper,
-                Level:   5,
+                Level: 6, // Nginx default compression level
         }))
 }
 
diff --git a/echo/prometheus/prometheus.go b/echo/prometheus/prometheus.go
index 2fbf252..5f93bea 100644
--- a/echo/prometheus/prometheus.go
+++ b/echo/prometheus/prometheus.go
@@ -64,9 +64,19 @@ func NewPrometheusWithConfig(c *PrometheusConfig) *Prometheus {
                 c.ExtractHost = DefaultPrometheusConfig.ExtractHost
         }
 
+        // Mostly matches promhttp.Handler implementation
+        hnd := echo.WrapHandler(promhttp.InstrumentMetricHandler(
+                prometheus.DefaultRegisterer,
+                promhttp.HandlerFor(prometheus.DefaultGatherer, promhttp.HandlerOpts{
+                        // We gzip by default in the echo warpper; with this enabled we
+                        // double gzip metrics and corrupt them
+                        DisableCompression: true,
+                }),
+        ))
+
         return &Prometheus{
                 Config:         c,
-                MetricsHandler: echo.WrapHandler(promhttp.Handler()),
+                MetricsHandler: hnd,
                 requestCount: promauto.NewCounterVec(prometheus.CounterOpts{
                         Subsystem: c.Subsystem,
                         Name:      "requests_total",