middleware.cfg to configure middleware directives (#496)

* Use go generate to build middleware setup based on middleware.cfg
Init default config

* generated files

* Move gen to an isolated area

* rename files

* PR review updates

* undo readme

Makefile

@@ -48,6 +48,10 @@ clean:
 	go clean
 	rm -f coredns
 
+.PHONY: gen
+gen:
+	go generate ./core/...
+
 .PHONY: distclean
 distclean: clean
 	# Clean all dependencies and build artifacts

core/coredns.go

 // Package core registers the server and all plugins we support.
+
+// Additional middleware packages
+//go:generate go run ../gen/directives_generate.go ../middleware.cfg
 package core
 
 import (

core/dnsserver/directives.go

+//go:generate go run ../../gen/directives_generate.go ../../middleware.cfg
 package dnsserver
 
 import (
@@ -62,40 +63,3 @@ func RegisterDevDirective(name, before string) {
 	}
 	fmt.Printf("[INFO] %s\n", msg)
 }
-
-// Add here, and in core/coredns.go to use them.
-
-// Directives are registered in the order they should be
-// executed.
-//
-// Ordering is VERY important. Every middleware will
-// feel the effects of all other middleware below
-// (after) them during a request, but they must not
-// care what middleware above them are doing.
-var directives = []string{
-	"root",
-	"bind",
-	"trace",
-	"health",
-	"pprof",
-
-	"prometheus",
-	"errors",
-	"log",
-	"chaos",
-	"cache",
-
-	"rewrite",
-	"loadbalance",
-
-	"dnssec",
-	"file",
-	"auto",
-	"secondary",
-	"etcd",
-	"kubernetes",
-	"proxy",
-	"httpproxy",
-	"whoami",
-	"erratic",
-}

core/dnsserver/zdirectives.go

+// generated by directives_generate.go; DO NOT EDIT
+package dnsserver
+
+
+// Directives are registered in the order they should be
+// executed.
+//
+// Ordering is VERY important. Every middleware will
+// feel the effects of all other middleware below
+// (after) them during a request, but they must not
+// care what middleware above them are doing.
+
+var directives = []string{
+		"root",
+		"bind",
+		"trace",
+		"health",
+		"pprof",
+		"prometheus",
+		"errors",
+		"log",
+		"chaos",
+		"cache",
+		"rewrite",
+		"loadbalance",
+		"dnssec",
+		"file",
+		"auto",
+		"secondary",
+		"etcd",
+		"kubernetes",
+		"proxy",
+		"httpprox",
+		"whoami",
+		"erratic",
+}

core/zmiddleware.go

+// generated by directives_generate.go; DO NOT EDIT
+package core
+
+import ()

gen/directives_generate.go

+package main
+
+import (
+	"bufio"
+	"io/ioutil"
+	"os"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+var middlewarePath = "github.com/miekg/coredns/middleware/"
+var header = "// generated by directives_generate.go; DO NOT EDIT\n"
+
+func main() {
+	mwFile := os.Args[1]
+
+	mi := make(map[string]string, 0)
+	md := make(map[int]string, 0)
+
+	if file, err := os.Open(mwFile); err == nil {
+		defer file.Close()
+
+		scanner := bufio.NewScanner(file)
+		for scanner.Scan() {
+			line := scanner.Text()
+			if !strings.HasPrefix(line, `//`) && !strings.HasPrefix(line, "#") {
+				items := strings.Split(line, ":")
+				if len(items) == 3 {
+					if priority, err := strconv.Atoi(items[0]); err == nil {
+						md[priority] = items[1]
+					}
+
+					if items[2] != "" {
+						if strings.Contains(items[2], "/") {
+							mi[items[1]] = items[2]
+						} else {
+							mi[items[1]] = middlewarePath + items[2]
+						}
+					}
+
+				}
+			}
+		}
+
+		var orders []int
+		for k := range md {
+			orders = append(orders, k)
+		}
+		sort.Ints(orders)
+
+		if os.Getenv("GOPACKAGE") == "core" {
+			genImports("zmiddleware.go", mi)
+		}
+		if os.Getenv("GOPACKAGE") == "dnsserver" {
+			genDirectives("zdirectives.go", md)
+		}
+
+	} else {
+		os.Exit(1)
+	}
+	os.Exit(0)
+
+}
+
+func genImports(file string, mi map[string]string) {
+	outs := header + "package " + os.Getenv("GOPACKAGE") + "\n\n" + "import ("
+
+	if len(mi) > 0 {
+		outs += "\n"
+	}
+
+	for _, v := range mi {
+		outs += "		_ \"" + v + "\"\n"
+	}
+	outs += ")\n"
+
+	err := ioutil.WriteFile(file, []byte(outs), 0644)
+	if err != nil {
+		os.Exit(1)
+	}
+
+}
+
+func genDirectives(file string, md map[int]string) {
+
+	outs := header + "package " + os.Getenv("GOPACKAGE") + "\n\n"
+	outs += `
+// Directives are registered in the order they should be
+// executed.
+//
+// Ordering is VERY important. Every middleware will
+// feel the effects of all other middleware below
+// (after) them during a request, but they must not
+// care what middleware above them are doing.
+
+var directives = []string{
+`
+
+	var orders []int
+	for k := range md {
+		orders = append(orders, k)
+	}
+	sort.Ints(orders)
+
+	for _, k := range orders {
+		outs += "		\"" + md[k] + "\",\n"
+	}
+
+	outs += "}\n"
+
+	err := ioutil.WriteFile(file, []byte(outs), 0644)
+	if err != nil {
+		os.Exit(1)
+	}
+}

middleware.cfg

+# Directives are registered in the order they should be
+# executed.
+#
+# Ordering is VERY important. Every middleware will
+# feel the effects of all other middleware below
+# (after) them during a request, but they must not
+# care what middleware above them are doing.
+
+
+# How to rebuild with updated middleware configurations:
+# Modify the list below and run `make gen && make`
+
+# The parser takes the input format of
+#     <order>:<middleware-name>:<package-name>
+# OR
+#     <order>:<middleware-name>:
+# External middleware example:
+# 80:log:github.com/miekg/coredns/middleware/log
+# Local middleware example:
+# 80:log:
+
+10:root:
+20:bind:
+30:trace:
+40:health:
+50:pprof:
+60:prometheus:
+70:errors:
+80:log:
+90:chaos:
+100:cache:
+110:rewrite:
+120:loadbalance:
+130:dnssec:
+140:file:
+150:auto:
+160:secondary:
+170:etcd:
+180:kubernetes:
+190:proxy:
+200:httpprox:
+210:whoami:
+220:erratic: