grafana/pkg/middleware/gziper.go
Ben Sully 51c94bccd7
api: ignore /api/gnet proxy when gzipping responses (#71437)
This PR adds /api/gnet to the list of ignored paths in the gzip middleware.

Without this, when gzip is enabled (`server.enable_gzip = true`), responses
from the gnet proxy are double compressed: once by grafana.com and once by
Grafana itself. With this change we only do one round of compression for these
endpoints.

To test this out, try a request like this with `server.enable_gzip = true`
(after setting `GCOM_TOKEN` to a valid grafana.com token; you may need to
change the 'bsull' slug, too):

    curl -v --user admin:admin \
        -H "X-Api-Key: $GCOM_TOKEN" \
        -H 'Accept-Encoding: gzip' \
        localhost:3000/api/gnet/instances/bsull/provisioned-plugins/grafana-ml-app | gzip -d

Note that there are two Content-Encoding: gzip headers before this PR, and
the output is still compressed even after the `gzip -d`. After this PR things
look as expected.
2023-07-13 07:51:25 +01:00

82 lines
2.2 KiB
Go

package middleware
import (
"bufio"
"compress/gzip"
"fmt"
"net"
"net/http"
"strings"
"github.com/grafana/grafana/pkg/web"
)
type gzipResponseWriter struct {
w *gzip.Writer
web.ResponseWriter
}
func (grw *gzipResponseWriter) WriteHeader(c int) {
grw.Header().Del("Content-Length")
grw.ResponseWriter.WriteHeader(c)
}
func (grw gzipResponseWriter) Write(p []byte) (int, error) {
if grw.Header().Get("Content-Type") == "" {
grw.Header().Set("Content-Type", http.DetectContentType(p))
}
grw.Header().Del("Content-Length")
return grw.w.Write(p)
}
func (grw gzipResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
if hijacker, ok := grw.ResponseWriter.(http.Hijacker); ok {
return hijacker.Hijack()
}
return nil, nil, fmt.Errorf("GZIP ResponseWriter doesn't implement the Hijacker interface")
}
type matcher func(s string) bool
func prefix(p string) matcher { return func(s string) bool { return strings.HasPrefix(s, p) } }
func substr(p string) matcher { return func(s string) bool { return strings.Contains(s, p) } }
var gzipIgnoredPaths = []matcher{
prefix("/api/datasources"),
prefix("/api/plugins"),
prefix("/api/plugin-proxy/"),
prefix("/api/gnet/"), // Already gzipped by grafana.com.
prefix("/metrics"),
prefix("/api/live/ws"), // WebSocket does not support gzip compression.
prefix("/api/live/push"), // WebSocket does not support gzip compression.
substr("/resources"),
}
func Gziper() func(http.Handler) http.Handler {
return func(next http.Handler) http.Handler {
return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
requestPath := req.URL.RequestURI()
for _, pathMatcher := range gzipIgnoredPaths {
if pathMatcher(requestPath) {
next.ServeHTTP(rw, req)
return
}
}
if !strings.Contains(req.Header.Get("Accept-Encoding"), "gzip") {
next.ServeHTTP(rw, req)
return
}
grw := &gzipResponseWriter{gzip.NewWriter(rw), rw.(web.ResponseWriter)}
grw.Header().Set("Content-Encoding", "gzip")
grw.Header().Set("Vary", "Accept-Encoding")
next.ServeHTTP(grw, req)
// We can't really handle close errors at this point and we can't report them to the caller
_ = grw.w.Close()
})
}
}