config: add support for policies stored in the databroker (#1099)

* wip

* always use databroker config source

* add test

* valid policy, remove debug lines

internal/databroker/config_source_test.go

@@ -0,0 +1,84 @@
+package databroker
+
+import (
+	"context"
+	"net"
+	"net/url"
+	"testing"
+	"time"
+
+	"github.com/golang/protobuf/ptypes"
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/grpc"
+
+	"github.com/pomerium/pomerium/config"
+	configpb "github.com/pomerium/pomerium/pkg/grpc/config"
+	"github.com/pomerium/pomerium/pkg/grpc/databroker"
+)
+
+func TestConfigSource(t *testing.T) {
+	ctx, clearTimeout := context.WithTimeout(context.Background(), 5*time.Second)
+	defer clearTimeout()
+
+	li, err := net.Listen("tcp", "127.0.0.1:0")
+	if !assert.NoError(t, err) {
+		return
+	}
+	defer li.Close()
+
+	db := New()
+	srv := grpc.NewServer()
+	databroker.RegisterDataBrokerServiceServer(srv, db)
+	go func() { _ = srv.Serve(li) }()
+
+	cfgs := make(chan *config.Config, 10)
+
+	src := NewConfigSource(config.NewStaticSource(&config.Config{
+		Options: &config.Options{
+			DataBrokerURL: mustParse("http://" + li.Addr().String()),
+			GRPCInsecure:  true,
+		},
+	}), func(cfg *config.Config) {
+		cfgs <- cfg
+	})
+	cfgs <- src.GetConfig()
+
+	data, _ := ptypes.MarshalAny(&configpb.Config{
+		Name: "config",
+		Policies: []*configpb.Policy{
+			{
+				From: "https://from.example.com",
+				To:   "https://to.example.com",
+			},
+		},
+	})
+	_, _ = db.Set(ctx, &databroker.SetRequest{
+		Type: configTypeURL,
+		Id:   "1",
+		Data: data,
+	})
+
+	select {
+	case <-ctx.Done():
+		assert.NoError(t, ctx.Err())
+		return
+	case cfg := <-cfgs:
+		assert.Len(t, cfg.Options.Policies, 0)
+	}
+
+	select {
+	case <-ctx.Done():
+		assert.NoError(t, ctx.Err())
+		return
+	case cfg := <-cfgs:
+		assert.Len(t, cfg.Options.Policies, 1)
+	}
+}
+
+func mustParse(raw string) *url.URL {
+	u, err := url.Parse(raw)
+	if err != nil {
+		panic(err)
+	}
+	return u
+}