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reverse_proxy.go
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reverse_proxy.go
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package main
import (
"flag"
"fmt"
"log"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"github.com/davecgh/go-spew/spew"
"github.com/influxdata/influxql"
)
var (
addr = flag.String("listen.addr", "127.0.0.1:9094", "listen address")
dest = flag.String("influx.path", "http://influx-node:8086", "influx address")
)
func main() {
flag.Parse()
u, err := url.Parse(*dest)
if err != nil {
log.Fatalln(err)
}
director := func(req *http.Request) {
req.URL.Scheme = u.Scheme
req.URL.Host = u.Host
req.Host = u.Host
path := strings.SplitN(req.URL.Path, "/", 3)
if len(path) != 3 || path[0] != "" || path[2] != "query" {
log.Printf("invalid path: %v", req.URL)
req.URL = nil
return
}
client := path[1]
req.URL.Path = "/query"
uquery := req.URL.Query()
query := uquery.Get("q")
q, err := influxql.ParseQuery(query)
if err != nil {
log.Printf("invalid query (%s): %v", query, err)
req.URL = nil
return
}
for i, st := range q.Statements {
switch st := st.(type) {
case *influxql.SelectStatement:
st, err := rewriteSelect(client, st)
if err != nil {
log.Printf("failed rewrite (%s): %v", query, err)
req.URL = nil
return
}
q.Statements[i] = st
case *influxql.ShowTagValuesStatement:
q.Statements[i].(*influxql.ShowTagValuesStatement).Condition = rewriteCond(client, st.Condition)
case *influxql.ShowTagKeysStatement,
*influxql.ShowFieldKeysStatement,
*influxql.ShowMeasurementsStatement,
*influxql.ShowDatabasesStatement,
*influxql.ShowRetentionPoliciesStatement:
// Allowed
default:
// Ban by default
spew.Dump("unknown statement", st)
req.URL = nil
return
}
}
uquery.Set("q", q.Statements.String())
req.URL.RawQuery = uquery.Encode()
}
proxy := &httputil.ReverseProxy{Director: director}
log.Fatalln(http.ListenAndServe(*addr, proxy))
}
func rewriteCond(client string, expr influxql.Expr) influxql.Expr {
if expr == nil {
return &influxql.BinaryExpr{
Op: influxql.EQ,
LHS: &influxql.VarRef{Val: "client"},
RHS: &influxql.StringLiteral{Val: client},
}
}
return &influxql.BinaryExpr{
Op: influxql.AND,
LHS: &influxql.BinaryExpr{
Op: influxql.EQ,
LHS: &influxql.VarRef{Val: "client"},
RHS: &influxql.StringLiteral{Val: client},
},
RHS: expr,
}
}
func rewriteSelect(client string, st *influxql.SelectStatement) (*influxql.SelectStatement, error) {
for i, src := range st.Sources {
switch src := src.(type) {
case *influxql.Measurement:
case *influxql.SubQuery:
s, err := rewriteSelect(client, src.Statement)
if err != nil {
return nil, err
}
st.Sources[i].(*influxql.SubQuery).Statement = s
default:
return nil, fmt.Errorf("unknown source: %T", src)
}
}
st.Condition = rewriteCond(client, st.Condition)
return st, nil
}