Make app/ a Go module.

Dockerfile

@@ -5,7 +5,7 @@ RUN apk --no-cache add git make rsync zip python3 py3-beautifulsoup4 coreutils
 
 # Build app
 COPY app /app
-RUN go build -o /app/up /app/up.go
+RUN cd /app && go build -o up .
 
 # Set up user and directories.
 RUN adduser -D -g '' builder

app/go.mod

@@ -0,0 +1,3 @@
+module github.com/elves/up/app
+
+go 1.22.0

app/up.go

@@ -8,7 +8,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"flag"
-	"io/ioutil"
+	"io"
 	"log"
 	"net/http"
 	"os"
@@ -29,7 +29,7 @@ type Payload struct {
 func main() {
 	flag.Parse()
 
-	secretBytes, err := ioutil.ReadFile(*secretFlag)
+	secretBytes, err := os.ReadFile(*secretFlag)
 	if err != nil {
 		log.Fatalln("failed to read secret file:", err)
 	}
@@ -40,7 +40,7 @@ func main() {
 
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		log.Println("handling request")
-		payload, err := ioutil.ReadAll(r.Body)
+		payload, err := io.ReadAll(r.Body)
 		if err != nil {
 			log.Println("failed to read HTTP request:", err)
 			return