feat: implements circuitbreaker layer

internal/config/layers.go

@@ -3,7 +3,8 @@ package config
 import "time"
 
 type LayersConfig struct {
-	Queue QueueLayerConfig `yaml:"queue"`
+	Queue          QueueLayerConfig          `yaml:"queue"`
+	CircuitBreaker CircuitBreakerLayerConfig `yaml:"circuitbreaker"`
 }
 
 func NewDefaultLayersConfig() LayersConfig {
@@ -12,6 +13,9 @@ func NewDefaultLayersConfig() LayersConfig {
 			TemplateDir:      "./layers/queue/templates",
 			DefaultKeepAlive: NewInterpolatedDuration(time.Minute),
 		},
+		CircuitBreaker: CircuitBreakerLayerConfig{
+			TemplateDir: "./layers/circuitbreaker/templates",
+		},
 	}
 }
 
@@ -19,3 +23,7 @@ type QueueLayerConfig struct {
 	TemplateDir      InterpolatedString    `yaml:"templateDir"`
 	DefaultKeepAlive *InterpolatedDuration `yaml:"defaultKeepAlive"`
 }
+
+type CircuitBreakerLayerConfig struct {
+	TemplateDir InterpolatedString `yaml:"templateDir"`
+}

internal/proxy/director/layer/circuitbreaker/layer-options.json

@@ -0,0 +1,23 @@
+{
+    "$id": "https://forge.cadoles.com/cadoles/bouncer/schemas/circuitbreaker-layer-options",
+    "title": "Circuit breaker layer options",
+    "type": "object",
+    "properties": {
+        "matchURLs": {
+            "type": "array",
+            "items": {
+                "type": "string"
+            }
+        },
+        "authorizedCIDRs": {
+            "type": "array",
+            "items": {
+                "type": "string"
+            }
+        },
+        "templateBlock": {
+            "type": "string"
+        }
+    },
+    "additionalProperties": false
+}

internal/proxy/director/layer/circuitbreaker/layer.go

@@ -0,0 +1,151 @@
+package circuitbreaker
+
+import (
+	"context"
+	"html/template"
+	"net"
+	"net/http"
+	"path/filepath"
+	"sync"
+
+	"forge.cadoles.com/Cadoles/go-proxy"
+	"forge.cadoles.com/Cadoles/go-proxy/wildcard"
+	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
+	"forge.cadoles.com/cadoles/bouncer/internal/store"
+	"github.com/Masterminds/sprig/v3"
+	"github.com/pkg/errors"
+	"gitlab.com/wpetit/goweb/logger"
+)
+
+const LayerType store.LayerType = "circuitbreaker"
+
+type Layer struct {
+	templateDir string
+	loadOnce    sync.Once
+	tmpl        *template.Template
+}
+
+// LayerType implements director.MiddlewareLayer
+func (l *Layer) LayerType() store.LayerType {
+	return LayerType
+}
+
+// Middleware implements director.MiddlewareLayer
+func (l *Layer) Middleware(layer *store.Layer) proxy.Middleware {
+	return func(h http.Handler) http.Handler {
+		fn := func(w http.ResponseWriter, r *http.Request) {
+			ctx := r.Context()
+
+			options, err := fromStoreOptions(layer.Options)
+			if err != nil {
+				logger.Error(ctx, "could not parse layer options", logger.E(errors.WithStack(err)))
+				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+
+				return
+			}
+
+			matches, err := l.matchAnyAuthorizedCIDRs(ctx, r.RemoteAddr, options.AuthorizedCIDRs)
+			if err != nil {
+				logger.Error(ctx, "could not match authorized cidrs", logger.E(errors.WithStack(err)))
+				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+
+				return
+			}
+
+			if matches {
+				h.ServeHTTP(w, r)
+
+				return
+			}
+
+			matches = wildcard.MatchAny(r.URL.String(), options.MatchURLs...)
+			if !matches {
+				h.ServeHTTP(w, r)
+
+				return
+			}
+
+			l.renderCircuitBreakerPage(w, r, layer, options)
+		}
+
+		return http.HandlerFunc(fn)
+	}
+}
+
+func (l *Layer) matchAnyAuthorizedCIDRs(ctx context.Context, remoteHostPort string, CIDRs []string) (bool, error) {
+	remoteHost, _, err := net.SplitHostPort(remoteHostPort)
+	if err != nil {
+		return false, errors.WithStack(err)
+	}
+
+	remoteAddr := net.ParseIP(remoteHost)
+	if remoteAddr == nil {
+		return false, errors.Errorf("remote host '%s' is not a valid ip address", remoteHost)
+	}
+
+	for _, rawCIDR := range CIDRs {
+		_, net, err := net.ParseCIDR(rawCIDR)
+		if err != nil {
+			return false, errors.WithStack(err)
+		}
+
+		match := net.Contains(remoteAddr)
+		if !match {
+			continue
+		}
+
+		return true, nil
+	}
+
+	logger.Debug(ctx, "comparing remote host with authorized cidrs", logger.F("remoteAddr", remoteAddr))
+
+	return false, nil
+}
+
+func (l *Layer) renderCircuitBreakerPage(w http.ResponseWriter, r *http.Request, layer *store.Layer, options *LayerOptions) {
+	ctx := r.Context()
+
+	pattern := filepath.Join(l.templateDir, "*.gohtml")
+
+	logger.Info(ctx, "loading circuit breaker page templates", logger.F("pattern", pattern))
+
+	tmpl, err := template.New("").Funcs(sprig.FuncMap()).ParseGlob(pattern)
+	if err != nil {
+		logger.Error(ctx, "could not load circuit breaker templates", logger.E(errors.WithStack(err)))
+		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+
+		return
+	}
+
+	templateData := struct {
+		Layer        *store.Layer
+		LayerOptions *LayerOptions
+	}{
+		Layer:        layer,
+		LayerOptions: options,
+	}
+
+	w.Header().Add("Cache-Control", "no-cache")
+
+	w.WriteHeader(http.StatusOK)
+
+	if err := tmpl.ExecuteTemplate(w, options.TemplateBlock, templateData); err != nil {
+		logger.Error(ctx, "could not render circuit breaker page", logger.E(errors.WithStack(err)))
+		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+
+		return
+	}
+}
+
+func New(funcs ...OptionFunc) *Layer {
+	opts := defaultOptions()
+	for _, fn := range funcs {
+		fn(opts)
+	}
+
+	return &Layer{
+		templateDir: opts.TemplateDir,
+	}
+}
+
+var _ director.MiddlewareLayer = &Layer{}

internal/proxy/director/layer/circuitbreaker/layer_options.go

@@ -0,0 +1,36 @@
+package circuitbreaker
+
+import (
+	"forge.cadoles.com/cadoles/bouncer/internal/store"
+	"github.com/mitchellh/mapstructure"
+	"github.com/pkg/errors"
+)
+
+type LayerOptions struct {
+	MatchURLs       []string `mapstructure:"matchURLs"`
+	AuthorizedCIDRs []string `mapstructure:"authorizedCIDRs"`
+	TemplateBlock   string   `mapstructure:"templateBlock"`
+}
+
+func fromStoreOptions(storeOptions store.LayerOptions) (*LayerOptions, error) {
+	layerOptions := LayerOptions{
+		MatchURLs:       []string{"*"},
+		AuthorizedCIDRs: []string{},
+		TemplateBlock:   "default",
+	}
+
+	config := mapstructure.DecoderConfig{
+		Result: &layerOptions,
+	}
+
+	decoder, err := mapstructure.NewDecoder(&config)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := decoder.Decode(storeOptions); err != nil {
+		return nil, errors.WithStack(err)
+	}
+
+	return &layerOptions, nil
+}

internal/proxy/director/layer/circuitbreaker/options.go

@@ -0,0 +1,19 @@
+package circuitbreaker
+
+type Options struct {
+	TemplateDir string
+}
+
+type OptionFunc func(*Options)
+
+func defaultOptions() *Options {
+	return &Options{
+		TemplateDir: "./templates",
+	}
+}
+
+func WithTemplateDir(templateDir string) OptionFunc {
+	return func(o *Options) {
+		o.TemplateDir = templateDir
+	}
+}

internal/proxy/director/layer/circuitbreaker/schema.go

@@ -0,0 +1,8 @@
+package circuitbreaker
+
+import (
+	_ "embed"
+)
+
+//go:embed layer-options.json
+var RawLayerOptionsSchema []byte

internal/setup/circuitbreaker_layer.go

@@ -0,0 +1,21 @@
+package setup
+
+import (
+	"forge.cadoles.com/cadoles/bouncer/internal/config"
+	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director"
+	"forge.cadoles.com/cadoles/bouncer/internal/proxy/director/layer/circuitbreaker"
+)
+
+func init() {
+	RegisterLayer(circuitbreaker.LayerType, setupCircuitBreakerLayer, circuitbreaker.RawLayerOptionsSchema)
+}
+
+func setupCircuitBreakerLayer(conf *config.Config) (director.Layer, error) {
+	options := []circuitbreaker.OptionFunc{
+		circuitbreaker.WithTemplateDir(string(conf.Layers.CircuitBreaker.TemplateDir)),
+	}
+
+	return circuitbreaker.New(
+		options...,
+	), nil
+}