allow overriding GIT_TAG for make build target to fix publishing docker images

.drone.yml

@@ -119,6 +119,8 @@ steps:
         from_secret: docker_username
       password:
         from_secret: docker_password
+      build_args:
+        - GIT_TAG_OVERRIDE=${DRONE_TAG}
     depends_on:
       - lint
       - test
@@ -135,12 +137,14 @@ steps:
         - latest
         - "${DRONE_TAG}"
       dockerfile: Dockerfile
-      target: dind
+      target: binary-only
       context: .
       username:
         from_secret: docker_username
       password:
         from_secret: docker_password
+      build_args:
+        - GIT_TAG_OVERRIDE=${DRONE_TAG}
     depends_on:
       - lint
       - test

Dockerfile

@@ -1,7 +1,8 @@
 FROM golang:1.15 as builder
+ARG GIT_TAG_OVERRIDE
 WORKDIR /app
 COPY . .
-RUN make build && bin/k3d version
+RUN make build -e GIT_TAG_OVERRIDE=${GIT_TAG_OVERRIDE} && bin/k3d version
 
 FROM docker:19.03-dind as dind
 RUN apk update && apk add bash curl sudo jq git make netcat-openbsd

Makefile

@@ -16,6 +16,11 @@ export GO111MODULE=on
 ########## Tags ##########
 
 # get git tag
+ifneq ($(GIT_TAG_OVERRIDE),)
+$(info GIT_TAG set from env override!)
+GIT_TAG := $(GIT_TAG_OVERRIDE)
+endif
+
 GIT_TAG   ?= $(shell git describe --tags)
 ifeq ($(GIT_TAG),)
 GIT_TAG   := $(shell git describe --always)