Use go-githubapp client caching (#91)

config/policy-bot.example.yml

@@ -15,6 +15,11 @@ logging:
   # Choose from: debug, info, warn, error
   level: debug
 
+# Options for the HTTP Cache
+cache:
+  # The maximum size of the cache (specified in human readable units)
+  max_size: 50 MB
+
 # Options for connecting to GitHub
 github:
   # The URL of the GitHub homepage

server/config.go

@@ -15,6 +15,7 @@
 package server
 
 import (
+	"github.com/c2h5oh/datasize"
 	"github.com/palantir/go-baseapp/baseapp"
 	"github.com/palantir/go-baseapp/baseapp/datadog"
 	"github.com/palantir/go-githubapp/githubapp"
@@ -27,6 +28,7 @@ import (
 type Config struct {
 	Server   baseapp.HTTPConfig            `yaml:"server"`
 	Logging  LoggingConfig                 `yaml:"logging"`
+	Cache    CachingConfig                 `yaml:"cache"`
 	Github   githubapp.Config              `yaml:"github"`
 	Sessions SessionsConfig                `yaml:"sessions"`
 	Options  handler.PullEvaluationOptions `yaml:"options"`
@@ -39,6 +41,10 @@ type LoggingConfig struct {
 	Text  bool   `yaml:"text" json:"text"`
 }
 
+type CachingConfig struct {
+	MaxSize datasize.ByteSize `yaml:"max_size"`
+}
+
 type SessionsConfig struct {
 	Key      string `yaml:"key"`
 	Lifetime string `yaml:"lifetime"`

server/server.go

@@ -22,6 +22,9 @@ import (
 
 	"github.com/alexedwards/scs"
 	"github.com/bluekeyes/hatpear"
+	"github.com/c2h5oh/datasize"
+	"github.com/die-net/lrucache"
+	"github.com/gregjones/httpcache"
 	"github.com/palantir/go-baseapp/baseapp"
 	"github.com/palantir/go-baseapp/baseapp/datadog"
 	"github.com/palantir/go-githubapp/githubapp"
@@ -76,10 +79,18 @@ func New(c *Config) (*Server, error) {
 		return nil, errors.Wrap(err, "failed to initialize base server")
 	}
 
+	maxSize := int64(50 * datasize.MB)
+	if c.Cache.MaxSize != 0 {
+		maxSize = int64(c.Cache.MaxSize)
+	}
+
 	userAgent := fmt.Sprintf("%s/%s", c.Options.AppName, version.GetVersion())
 	cc, err := githubapp.NewDefaultCachingClientCreator(
 		c.Github,
 		githubapp.WithClientUserAgent(userAgent),
+		githubapp.WithClientCaching(true, func() httpcache.Cache {
+			return lrucache.New(maxSize, 0)
+		}),
 		githubapp.WithClientMiddleware(
 			githubapp.ClientLogging(zerolog.DebugLevel),
 			githubapp.ClientMetrics(base.Registry()),