Extract cutoff delta to configuration file

README.md

@@ -39,13 +39,16 @@ publisher:
     url: "gcppubsub://foobar.com"
 
 http_port: 8080
+
+cutoff_delta: 5m
 ```
 
-To specify this configuration file, define its path in your environment under the `PACKAGE_FEEDS_CONFIG_PATH` variable.
+`cutoff_delta` string formatted for [duration parser](https://golang.org/pkg/time/#ParseDuration). To specify this configuration file, define its path in your environment under the `PACKAGE_FEEDS_CONFIG_PATH` variable.
 
 ## Legacy Configuration
 
 Legacy configuration methods are still supported. By default, without a configuration file all feeds will be enabled. The environment variable `OSSMALWARE_TOPIC_URL` can be used to select the GCP pubsub publisher and `PORT` will configure the port for the HTTP server.
+The default `cutoff_delta` is 5 minutes, this is used to generate a cutoff point for feed events relative to the given time at execution.
 
 # Contributing
 

cmd/scheduled-feed/main.go

@@ -6,8 +6,8 @@ import (
 	"fmt"
 	"net/http"
 	"os"
-	"time"
 	"strings"
+	"time"
 
 	"github.com/ossf/package-feeds/config"
 	"github.com/ossf/package-feeds/feeds/scheduler"
@@ -16,16 +16,15 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-const delta = 5 * time.Minute
-
 // FeedHandler is a handler that fetches new packages from various feeds
 type FeedHandler struct {
 	scheduler *scheduler.Scheduler
 	pub       publisher.Publisher
+	delta     time.Duration
 }
 
 func (handler *FeedHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	cutoff := time.Now().UTC().Add(-delta)
+	cutoff := time.Now().UTC().Add(-handler.delta)
 	pkgs, errs := handler.scheduler.Poll(cutoff)
 	if len(errs) > 0 {
 		for _, err := range errs {
@@ -87,9 +86,14 @@ func main() {
 	sched := scheduler.New(feeds)
 
 	log.Printf("listening on port %v", appConfig.HttpPort)
+	delta, err := time.ParseDuration(appConfig.CutoffDelta)
+	if err != nil {
+		log.Fatal(err)
+	}
 	handler := &FeedHandler{
 		scheduler: sched,
 		pub:       pub,
+		delta:     delta,
 	}
 	http.Handle("/", handler)
 	if err := http.ListenAndServe(fmt.Sprintf(":%v", appConfig.HttpPort), nil); err != nil {

config/config_test.go

@@ -22,6 +22,7 @@ publisher:
     endpoint: "https://foobaz.com"
 
 http_port: 8080
+cutoff_delta: 5m
 `
 	TestConfigStrUnknownFeedType = `
 enabled_feeds:

config/scheduledfeed.go

@@ -152,7 +152,8 @@ func Default() *ScheduledFeedConfig {
 		PubConfig: PublisherConfig{
 			Type: stdout.PublisherType,
 		},
-		HttpPort: 8080,
+		HttpPort:    8080,
+		CutoffDelta: "5m",
 	}
 	config.applyEnvVars()
 	return config

config/structs.go

@@ -4,6 +4,7 @@ type ScheduledFeedConfig struct {
 	PubConfig    PublisherConfig `yaml:"publisher"`
 	EnabledFeeds []string        `yaml:"enabled_feeds"`
 	HttpPort     int             `yaml:"http_port,omitempty"`
+	CutoffDelta  string          `yaml:"cutoff_delta"`
 }
 
 type PublisherConfig struct {