kg: add new handler for rendering the topology graph via the metrics webserver

Dockerfile

@@ -11,7 +11,7 @@ ARG GOARCH
 ARG ALPINE_VERSION=v3.12
 LABEL maintainer="squat <lserven@gmail.com>"
 RUN echo -e "https://alpine.global.ssl.fastly.net/alpine/$ALPINE_VERSION/main\nhttps://alpine.global.ssl.fastly.net/alpine/$ALPINE_VERSION/community" > /etc/apk/repositories && \
-    apk add --no-cache ipset iptables ip6tables wireguard-tools
+    apk add --no-cache ipset iptables ip6tables wireguard-tools graphviz font-noto
 COPY --from=cni bridge host-local loopback portmap /opt/cni/bin/
 COPY bin/linux/$GOARCH/kg /opt/bin/
 ENTRYPOINT ["/opt/bin/kg"]

Makefile

@@ -209,7 +209,7 @@ $(BASH_UNIT):
 	chmod +x $@
 
 e2e: container $(KIND_BINARY) $(KUBECTL_BINARY) $(BASH_UNIT) bin/$(OS)/$(ARCH)/kgctl
-	KILO_IMAGE=$(IMAGE):$(ARCH)-$(VERSION) KIND_BINARY=$(KIND_BINARY) KUBECTL_BINARY=$(KUBECTL_BINARY) KGCTL_BINARY=$(shell pwd)/bin/$(OS)/$(ARCH)/kgctl $(BASH_UNIT) $(BASH_UNIT_FLAGS) ./e2e/setup.sh ./e2e/full-mesh.sh ./e2e/location-mesh.sh ./e2e/multi-cluster.sh ./e2e/teardown.sh
+	KILO_IMAGE=$(IMAGE):$(ARCH)-$(VERSION) KIND_BINARY=$(KIND_BINARY) KUBECTL_BINARY=$(KUBECTL_BINARY) KGCTL_BINARY=$(shell pwd)/bin/$(OS)/$(ARCH)/kgctl $(BASH_UNIT) $(BASH_UNIT_FLAGS) ./e2e/setup.sh ./e2e/full-mesh.sh ./e2e/location-mesh.sh ./e2e/multi-cluster.sh ./e2e/handlers.sh ./e2e/teardown.sh
 
 header: .header
 	@HEADER=$$(cat .header); \

cmd/kg/handlers.go

@@ -0,0 +1,145 @@
+// Copyright 2019 the Kilo authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"mime"
+	"net"
+	"net/http"
+	"os"
+	"os/exec"
+
+	"github.com/squat/kilo/pkg/mesh"
+)
+
+type graphHandler struct {
+	mesh        *mesh.Mesh
+	granularity mesh.Granularity
+	hostname    *string
+	subnet      *net.IPNet
+}
+
+func (h *graphHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	ns, err := h.mesh.Nodes().List()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to list nodes: %v", err), http.StatusInternalServerError)
+		return
+	}
+	ps, err := h.mesh.Peers().List()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to list peers: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	nodes := make(map[string]*mesh.Node)
+	for _, n := range ns {
+		if n.Ready() {
+			nodes[n.Name] = n
+		}
+	}
+	if len(nodes) == 0 {
+		http.Error(w, "did not find any valid Kilo nodes in the cluster", http.StatusInternalServerError)
+		return
+	}
+	peers := make(map[string]*mesh.Peer)
+	for _, p := range ps {
+		if p.Ready() {
+			peers[p.Name] = p
+		}
+	}
+	topo, err := mesh.NewTopology(nodes, peers, h.granularity, *h.hostname, 0, []byte{}, h.subnet, nodes[*h.hostname].PersistentKeepalive, nil)
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to create topology: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	dot, err := topo.Dot()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to generate graph: %v", err), http.StatusInternalServerError)
+	}
+
+	buf := bytes.NewBufferString(dot)
+
+	format := r.URL.Query().Get("format")
+	switch format {
+	case "":
+		format = "svg"
+	case "dot", "gv":
+		// If the raw dot data is requested, return it as string.
+		// This allows client-side rendering rather than server-side.
+		w.Write(buf.Bytes())
+		return
+
+	case "svg", "png", "bmp", "fig", "gif", "json", "ps":
+		// Accepted format
+
+	default:
+		http.Error(w, "unsupported format", http.StatusInternalServerError)
+		return
+	}
+
+	layout := r.URL.Query().Get("layout")
+	switch layout {
+	case "":
+		layout = "circo"
+
+	case "circo", "dot", "neato", "twopi", "fdp":
+		// Accepted layout
+
+	default:
+		http.Error(w, "unsupported layout", http.StatusInternalServerError)
+		return
+	}
+
+	command := exec.Command("dot", "-K"+layout, "-T"+format)
+	command.Stderr = os.Stderr
+
+	stdin, err := command.StdinPipe()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if _, err = io.Copy(stdin, buf); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if err = stdin.Close(); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	output, err := command.Output()
+	if err != nil {
+		http.Error(w, "unable to render graph", http.StatusInternalServerError)
+		return
+	}
+
+	mimeType := mime.TypeByExtension("." + format)
+	if mimeType == "" {
+		mimeType = "application/octet-stream"
+	}
+
+	w.Header().Add("content-type", mimeType)
+	w.Write(output)
+}
+
+func healthHandler(w http.ResponseWriter, _ *http.Request) {
+	w.WriteHeader(http.StatusOK)
+}

cmd/kg/main.go

@@ -196,9 +196,8 @@ func Main() error {
 	{
 		// Run the HTTP server.
 		mux := http.NewServeMux()
-		mux.HandleFunc("/health", func(w http.ResponseWriter, _ *http.Request) {
-			w.WriteHeader(http.StatusOK)
-		})
+		mux.HandleFunc("/health", healthHandler)
+		mux.Handle("/graph", &graphHandler{m, gr, hostname, s})
 		mux.Handle("/metrics", promhttp.HandlerFor(r, promhttp.HandlerOpts{}))
 		l, err := net.Listen("tcp", *listen)
 		if err != nil {

e2e/handlers.sh

@@ -0,0 +1,26 @@
+#!/usr/bin/env bash
+# shellcheck disable=SC1091
+. lib.sh
+
+setup_suite() {
+	# shellcheck disable=SC2016
+	block_until_ready_by_name kube-system kilo-userspace 
+	_kubectl wait pod -l app.kubernetes.io/name=adjacency --for=condition=Ready --timeout 3m
+}
+
+test_graph_handler() {
+    assert "curl_pod 'http://10.4.0.1:1107/graph?format=svg&layout=circo' | grep -q '<svg'" "graph handler should produce SVG output"
+    assert "curl_pod http://10.4.0.1:1107/graph?layout=circo | grep -q '<svg'" "graph handler should default to SVG output"
+    assert "curl_pod http://10.4.0.1:1107/graph | grep -q '<svg'" "graph handler should default to SVG output"
+    assert_fail "curl_pod http://10.4.0.1:1107/graph?layout=fake | grep -q '<svg'" "graph handler should reject invalid layout"
+    assert_fail "curl_pod http://10.4.0.1:1107/graph?format=fake | grep -q '<svg'" "graph handler should reject invalid format"
+}
+
+test_health_handler() {
+    assert "curl_pod http://10.4.0.1:1107/health" "health handler should return a status code of 200"
+}
+
+test_metrics_handler() {
+    assert "curl_pod http://10.4.0.1:1107/metrics" "metrics handler should return a status code of 200"
+    assert "(( $(curl_pod http://10.4.0.1:1107/metrics | grep -E ^kilo_nodes | cut -d " " -f 2) > 0 ))" "metrics handler should provide metric: kilo_nodes > 0"
+}