diff --git a/Dockerfile b/Dockerfile
index 9f1e450..2e6e482 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -2,9 +2,8 @@ FROM golang:1.21.1
 
 WORKDIR /app
 
-COPY go.mod ./
-RUN go mod download
-RUN go mod verify
+COPY go.mod go.sum ./
+RUN go mod download && go mod verify
 
 COPY . .
 RUN go build -v -o ./bin/server .
diff --git a/compose.yml b/compose.yml
index 2436ffa..e9bd91e 100644
--- a/compose.yml
+++ b/compose.yml
@@ -1,9 +1,9 @@
-version: '3'
 services:  
   app:
     build:
       context: . 
       dockerfile: Dockerfile
     ports:
+      # generated with "hash2addr lab.phc.dm.unipi.it/portainer-example"
       - "127.14.115.95:1091:4000" 
     restart: unless-stopped
diff --git a/go.mod b/go.mod
index 997c8f4..64db55f 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module git.phc.dm.unipi.it/phc/portainer-example
 
 go 1.21.1
+
+require github.com/alecthomas/repr v0.2.0 // indirect
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..41169e6
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+github.com/alecthomas/repr v0.2.0 h1:HAzS41CIzNW5syS8Mf9UwXhNH1J9aix/BvDRf1Ml2Yk=
+github.com/alecthomas/repr v0.2.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
diff --git a/main.go b/main.go
index 02c5883..672d65e 100644
--- a/main.go
+++ b/main.go
@@ -3,7 +3,6 @@ package main
 import (
 	"encoding/json"
 	"log"
-	"mime"
 	"net/http"
 )
 
@@ -15,8 +14,11 @@ func main() {
 			return
 		}
 
-		w.Header().Set("Content-Type", mime.TypeByExtension(".json"))
-		if err := json.NewEncoder(w).Encode("ok"); err != nil {
+		w.Header().Set("Content-Type", "application/json")
+		if err := json.NewEncoder(w).Encode(map[string]any{
+			"question": "Whats the answer to life the universe and everything?",
+			"answer":   42,
+		}); err != nil {
 			log.Fatal(err)
 			return
 		}