Update

Dockerfile

-FROM debian:stable-slim
+FROM debian:stable-slim as builder # define builder target
 
-ENV PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
-ENV HOME /
+# Environment PATH HOME HOSTNAME
+# ENV PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
+# ENV HOME /
 
-ARG BUILDDEPS
+# Prepare build dependencies and clean up
+ARG BUILD_DEPS
 RUN apt-get -q update && \
     DEBIAN_FRONTEND=noninteractive apt-get -qy upgrade && \
-    DEBIAN_FRONTEND=noninteractive apt-get -qy install --no-install-recommends ${BUILDDEPS} \
-        ca-certificates curl build-essential git && \
-    apt-get clean && rm -rf /var/lib/apt/lists/* && \
-        
+    DEBIAN_FRONTEND=noninteractive apt-get -qy install --no-install-recommends ${BUILD_DEPS} \
+        build-essential ca-certificates curl git iproute2 wget && \
+    apt-get clean && rm -rf /var/lib/apt/lists/*
+
+# Default command
 CMD ["bash"]

drone.yml

   # http://plugins.drone.io/drone-plugins/drone-docker/
   # https://github.com/drone-plugins/drone-docker
   when:
-    event: [ tag ]
+    event: [ tag ] # [ push, tag ]
   settings:
     dry_run: false
     registry: reg.unino.de
     insecure: false
-    #auth: authtoken
+    #auth: authtoken for registry
     username: { from_secret: reg-user }
     password: { from_secret: reg-pass }
     repo: reg.unino.de/develop/debian-${DRONE_REPO_NAMESPACE}-${DRONE_REPO_NAME}
     #mirror: registry-1.docker.io/library/debian:stable-slim
-    #bip: 172.17.0.1/24
-    context: /drone
+    bip: 172.17.0.1/16
+    context: /drone # defaults to root of git repo
     #custom_dns: 127.0.0.11
     storage_driver: overlay2 # aufs, overlay or vfs
     #debug: true
     #launch_debug: true
-    #target: production # Dockerfile build target e.g. production, debug
+    target: builder # Dockerfile build target e.g. builder, debug, production
     dockerfile: Dockerfile
     auto_tag: false
     auto_tag_suffix: -linux-amd64
     force_tag: true
-    tags: [ latest ]
+    tags: [ latest, builder ]
     build_args:
-      - MAINTAINER=Drone CI/CD
-      - BUILDDEPS=libhidapi-dev libssl-dev zip
+      - BUILD_DEPS=libhidapi-dev libssl-dev zip
 
 
 - name: build
   # https://docs.drone.io/reference/environ/
   when:
     event: [ push, tag ]
-  depends_on: [ prepare ]
+  depends_on: [ clone, prepare ]
   environment:
     MAKEFLAGS: -j 1
   commands: