Adding sizelimit for file caching

Dockerfile

@@ -1,10 +1,10 @@
-FROM golang:1.16 AS builder
+FROM golang:1.17 AS builder
 WORKDIR /src
-COPY  . .
+COPY . .
 RUN CGO_ENABLED=0 GOOS=linux go build -o proxy .
 
-FROM alpine:latest  
+FROM alpine:latest
 RUN apk --no-cache add ca-certificates
 WORKDIR /
 COPY --from=builder /src/proxy .
-CMD ["./proxy"]  
+CMD ["./proxy"]

README.md

@@ -36,13 +36,14 @@ docker run -e S3PROXY_BUCKET=nameofmybucket -p 3000:3000 --rm -it codemonauts/s3
 ## Configuration
 All configuration happens via environment variables. 
 
-| Name            | Required | Default        | Description                                            |
-| --------------- | :------: | -------------- | ------------------------------------------------------ |
-| S3PROXY_BUCKET  |    x     | -              | Name of the bucket                                     |
-| S3PROXY_REGION  |          | "eu-central-1" | Region of the bucket                                   |
-| S3PROXY_PORT    |          | "3000"         | Listening port of the application                      |
-| S3PROXY_CACHING |          | ""             | Set this to a path if you wan't the files to be cached |
-| S3PROXY_LOGGING |          | "WARN"         | Loglevel ("ERROR","WARN","INFO","DEBUG")               |
+| Name              | Required | Default             | Description                                                  |
+| ----------------- | :------: | ------------------- | ------------------------------------------------------------ |
+| S3PROXY_BUCKET    |    x     | -                   | Name of the bucket                                           |
+| S3PROXY_REGION    |          | "eu-central-1"      | Region of the bucket                                         |
+| S3PROXY_PORT      |          | 3000                | Listening port of the application                            |
+| S3PROXY_CACHING   |          | ""                  | Set this to a path if you wan't the files to be cached       |
+| S3PROXY_SIZELIMIT |          | 104857600 ( ~100MB) | Only files smaller than this are cached. Set to 0 to disable |
+| S3PROXY_LOGGING   |          | "WARN"              | Loglevel ("ERROR","WARN","INFO","DEBUG")                     |
 
 
 ## Caching

proxy.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"os"
 	"path/filepath"
+	"strconv"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"
@@ -18,6 +19,7 @@ var (
 	s3Service  *s3.S3
 	bucketName string
 	cachePath  string
+	cacheLimit int64
 )
 
 // getFile checks if we have a local copy otherwise downloads from S3
@@ -107,6 +109,11 @@ func getFileFromBucket(key string) (FileWrapper, error) {
 	}
 
 	if cachePath != "" {
+		if *obj.ContentLength > cacheLimit {
+			log.Infof("Will not cache %q because it's to big (%d byte)\n", key, *obj.ContentLength)
+			return s3File, nil
+		}
+
 		path, err := saveFileToCache(key, obj)
 		if err != nil {
 			// We couldn't save the file to the cache but still return the Get response from S3
@@ -200,6 +207,7 @@ func main() {
 	port := envOrDefault("S3PROXY_PORT", "3000")
 	bucketName = envOrDefault("S3PROXY_BUCKET", "")
 	cachePath = envOrDefault("S3PROXY_CACHE", "")
+	cacheLimitEnv := envOrDefault("S3PROXY_SIZELIMIT", "104857600") // Default: 10 MB
 	logLevel := envOrDefault("S3PROXY_LOGGING", "WARN")
 
 	l, err := log.ParseLevel(logLevel)
@@ -225,13 +233,18 @@ func main() {
 
 	}
 
+	cacheLimit, err = strconv.ParseInt(cacheLimitEnv, 10, 64)
+	if err != nil {
+		log.Fatal("Could not parse the value of S3PROXY_SIZELIMIT into an integer")
+	}
+
 	sess := session.Must(session.NewSession(&aws.Config{
 		Region: aws.String(region),
 	}))
 	s3Service = s3.New(sess)
 
 	http.HandleFunc("/", handler)
 
-	log.Info("Listening on :%s \n", port)
+	log.Infof("Listening on :%s \n", port)
 	log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))
 }