cluster/admitomatic: finish up service

This turns admitomatic into a self-standing service that can be used as
an admission controller.

I've tested this E2E on a local k3s server, and have some early test
code for that - but that'll land up in a follow up CR, as it first needs
to be cleaned up.

Change-Id: I46da0fc49f9d1a3a1a96700a36deb82e5057249b

cluster/admitomatic/BUILD.bazel

@@ -5,15 +5,18 @@ go_library(
     srcs = [
         "ingress.go",
         "main.go",
+        "service.go",
     ],
     importpath = "code.hackerspace.pl/hscloud/cluster/admitomatic",
     visibility = ["//visibility:private"],
     deps = [
+        "//cluster/admitomatic/config:go_default_library",
         "//go/mirko:go_default_library",
         "@com_github_golang_glog//:go_default_library",
         "@io_k8s_api//admission/v1beta1:go_default_library",
         "@io_k8s_api//networking/v1beta1:go_default_library",
         "@io_k8s_apimachinery//pkg/apis/meta/v1:go_default_library",
+        "@org_golang_google_protobuf//encoding/prototext:go_default_library",
     ],
 )
 

cluster/admitomatic/config/BUILD.bazel

@@ -0,0 +1,23 @@
+load("@rules_proto//proto:defs.bzl", "proto_library")
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
+load("@io_bazel_rules_go//proto:def.bzl", "go_proto_library")
+
+proto_library(
+    name = "config_proto",
+    srcs = ["config.proto"],
+    visibility = ["//visibility:public"],
+)
+
+go_proto_library(
+    name = "config_go_proto",
+    importpath = "code.hackerspace.pl/hscloud/cluster/admitomatic/config",
+    proto = ":config_proto",
+    visibility = ["//visibility:public"],
+)
+
+go_library(
+    name = "go_default_library",
+    embed = [":config_go_proto"],
+    importpath = "code.hackerspace.pl/hscloud/cluster/admitomatic/config",
+    visibility = ["//visibility:public"],
+)

cluster/admitomatic/config/config.proto

@@ -0,0 +1,37 @@
+syntax = "proto3";
+package config;
+option go_package = "code.hackerspace.pl/hscloud/cluster/admitomatic/config";
+
+// Admitomatic configuration, passed as a text proto, for
+// example:
+//
+//  $ cat sample.pb.text
+//  allow_domain { namespace: "example" dns: "*.example.com" }
+//  allow_domain {
+//    namespace: "personal-q3k" dns: "foo.q3k.org"
+//  }
+//  allow_domain {
+//    namespace: "personal-q3k" dns: "bar.q3k.org"
+//  }
+//
+message Config {
+    // List of domains that are allowed to be configured as
+    // ingresses in a given namespace. If a domain does not
+    // appear in this list, it will be allowed to run in any
+    // namespace.
+    repeated AllowDomain allow_domain = 1;
+}
+
+message AllowDomain {
+    // namespace is a kubernetes namespace. An empty string is
+    // treated as the 'default' namespace.
+    string namespace = 1;
+    // dns is a domain name like 'example.com' or a wildcard
+    // like '*.foo.example.com'.
+    // Wildcards match domains at any level beneath the root,
+    // so the example above would match 'bar.foo.example.com'
+    // and 'baz.bar.foo.example.com'. However, they do not
+    // catch the root itself, ie. the above would not catch
+    // 'foo.example.com'.
+    string dns = 2;
+}

cluster/admitomatic/config/sample.pb.text

@@ -0,0 +1,7 @@
+allow_domain { namespace: "example" dns: "*.example.com" }
+allow_domain {
+  namespace: "personal-q3k" dns: "foo.q3k.org"
+}
+allow_domain {
+  namespace: "personal-q3k" dns: "bar.q3k.org"
+}

cluster/admitomatic/ingress.go

@@ -6,7 +6,6 @@ import (
 	"strings"
 
 	"github.com/golang/glog"
-
 	admission "k8s.io/api/admission/v1beta1"
 	networking "k8s.io/api/networking/v1beta1"
 	meta "k8s.io/apimachinery/pkg/apis/meta/v1"

cluster/admitomatic/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"flag"
+	"io/ioutil"
 	"net/http"
 	"time"
 
@@ -11,13 +12,29 @@ import (
 )
 
 var (
-	flagListen = "127.0.0.1:8080"
+	flagListen  = "127.0.0.1:8080"
+	flagConfig  = ""
+	flagTLSKey  = ""
+	flagTLSCert = ""
 )
 
 func main() {
-	flag.StringVar(&flagListen, "pub_listen", flagListen, "Address to listen on for HTTP traffic")
+	flag.StringVar(&flagListen, "admitomatic_listen", flagListen, "Address to listen on for HTTP traffic")
+	flag.StringVar(&flagTLSKey, "admitomatic_tls_key", flagTLSKey, "TLS key to serve HTTP with")
+	flag.StringVar(&flagTLSCert, "admitomatic_tls_cert", flagTLSCert, "TLS certificate to serve HTTP with")
+	flag.StringVar(&flagConfig, "admitomatic_config", flagConfig, "Config path (prototext format)")
 	flag.Parse()
 
+	if flagConfig == "" {
+		glog.Exitf("-admitomatic_config must be set")
+	}
+	if flagTLSKey == "" {
+		glog.Exitf("-admitomatic_tls_key must be set")
+	}
+	if flagTLSCert == "" {
+		glog.Exitf("-admitomatic_tls_cert must be set")
+	}
+
 	m := mirko.New()
 	if err := m.Listen(); err != nil {
 		glog.Exitf("Listen(): %v", err)
@@ -27,13 +44,24 @@ func main() {
 		glog.Exitf("Serve(): %v", err)
 	}
 
+	configData, err := ioutil.ReadFile(flagConfig)
+	if err != nil {
+		glog.Exitf("Could not read config: %v", err)
+	}
+
+	s, err := newService(configData)
+	if err != nil {
+		glog.Exitf("Could not start service: %v", err)
+	}
+
 	mux := http.NewServeMux()
+	mux.HandleFunc("/", s.handler)
 	// TODO(q3k): implement admission controller
 	srv := &http.Server{Addr: flagListen, Handler: mux}
 
 	glog.Infof("Listening on %q...", flagListen)
 	go func() {
-		if err := srv.ListenAndServe(); err != nil {
+		if err := srv.ListenAndServeTLS(flagTLSCert, flagTLSKey); err != nil {
 			glog.Error(err)
 		}
 	}()

cluster/admitomatic/service.go

@@ -0,0 +1,105 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/golang/glog"
+	"google.golang.org/protobuf/encoding/prototext"
+	admission "k8s.io/api/admission/v1beta1"
+	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	pb "code.hackerspace.pl/hscloud/cluster/admitomatic/config"
+)
+
+type service struct {
+	ingress ingressFilter
+}
+
+// newService creates an admitomatic service from a given prototext config.
+func newService(configuration []byte) (*service, error) {
+	var cfg pb.Config
+	if err := prototext.Unmarshal(configuration, &cfg); err != nil {
+		return nil, fmt.Errorf("parsing config: %v", err)
+	}
+
+	s := service{}
+
+	for i, ad := range cfg.AllowDomain {
+		if ad.Namespace == "" {
+			ad.Namespace = "default"
+		}
+		if ad.Dns == "" {
+			return nil, fmt.Errorf("config entry %d: dns must be set", i)
+		}
+		if err := s.ingress.allow(ad.Namespace, ad.Dns); err != nil {
+			return nil, fmt.Errorf("config entry %d: %v", i, err)
+		}
+		glog.Infof("Ingress: allowing %s in %s", ad.Dns, ad.Namespace)
+	}
+	return &s, nil
+}
+
+// handler is the main HTTP handler of the admitomatic service. It servers the
+// AdmissionReview API, and is called by the Kubernetes API server to
+// permit/deny creation/updating of resources.
+func (s *service) handler(w http.ResponseWriter, r *http.Request) {
+	var body []byte
+	if r.Body != nil {
+		if data, err := ioutil.ReadAll(r.Body); err == nil {
+			body = data
+		}
+	}
+
+	if r.Method != "POST" {
+		glog.Errorf("%s %s: invalid method", r.Method, r.URL)
+		return
+	}
+
+	contentType := r.Header.Get("Content-Type")
+	if contentType != "application/json" {
+		glog.Errorf("%s %s: invalid content-type", r.Method, r.URL)
+		return
+	}
+
+	var review admission.AdmissionReview
+	if err := json.Unmarshal(body, &review); err != nil {
+		glog.Errorf("%s %s: cannot decode: %v", r.Method, r.URL, err)
+		return
+	}
+
+	if review.Kind != "AdmissionReview" {
+		glog.Errorf("%s %s: invalid Kind (%q)", r.Method, r.URL, review.Kind)
+		return
+	}
+
+	var err error
+	req := review.Request
+	resp := &admission.AdmissionResponse{
+		UID:     req.UID,
+		Allowed: true,
+	}
+	switch {
+	case req.Kind.Group == "networking.k8s.io" && req.Kind.Kind == "Ingress":
+		resp, err = s.ingress.admit(req)
+		if err != nil {
+			glog.Errorf("%s %s %s: %v", req.Operation, req.Name, req.Namespace, err)
+			// Fail safe.
+			// TODO(q3k): monitor this?
+			resp = &admission.AdmissionResponse{
+				UID:     req.UID,
+				Allowed: false,
+				Result: &meta.Status{
+					Code:    500,
+					Message: "admitomatic: internal server error",
+				},
+			}
+		}
+	}
+
+	glog.Infof("%s %s %s in %s: %v (%v)", req.Operation, req.Kind.Kind, req.Name, req.Namespace, resp.Allowed, resp.Result)
+	review.Response = resp
+	json.NewEncoder(w).Encode(review)
+}