Upgrade base images to latest stable versions

It upgrades all alpine based images to version 3.15.
It also upgrades upf base image to debian bullseye release.
Also adds base env variable DEBIAN_FRONTEND.

base/Dockerfile

@@ -2,6 +2,8 @@ FROM golang:1.14.4-stretch AS builder
 
 LABEL maintainer="Free5GC <support@free5gc.org>"
 
+ENV DEBIAN_FRONTEND noninteractive
+
 # Install dependencies
 RUN apt-get update \
     && apt-get -y install gcc cmake autoconf libtool pkg-config libmnl-dev libyaml-dev apt-transport-https ca-certificates \
@@ -23,7 +25,7 @@ RUN cd $GOPATH/src/free5gc \
     && make all
 
 # Alpine is used for debug purpose. You can use scratch for a smaller footprint.
-FROM alpine
+FROM alpine:3.15
 
 WORKDIR /free5gc
 RUN mkdir -p config/ support/TLS/ public

nf_amf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_ausf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_n3iwf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_nrf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_nssf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_pcf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_smf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_udm/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_udr/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM alpine:3.13
+FROM alpine:3.15
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"

nf_upf/Dockerfile

@@ -1,5 +1,5 @@
 FROM free5gc/base:latest AS builder
-FROM bitnami/minideb:stretch
+FROM bitnami/minideb:bullseye
 
 LABEL description="Free5GC open source 5G Core Network" \
     version="Stage 3"