dockerfile: include a specific yq version that doesn't have issues with control characters when checking the lb config

Dockerfile

@@ -1,16 +1,37 @@
+############################################################
+# builder                                                  #
+# -> golang image used solely for building the k3d binary  #
+# -> built executable can then be copied into other stages #
+############################################################
 FROM golang:1.16 as builder
 ARG GIT_TAG_OVERRIDE
 WORKDIR /app
 COPY . .
 RUN make build -e GIT_TAG_OVERRIDE=${GIT_TAG_OVERRIDE} && bin/k3d version
 
+#######################################################
+# dind                                                #
+# -> k3d + some tools in a docker-in-docker container #
+# -> used e.g. in our CI pipelines for testing        #
+#######################################################
 FROM docker:20.10-dind as dind
-RUN apk update && apk add bash curl sudo jq yq git make netcat-openbsd
-RUN curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl && \
-    chmod +x ./kubectl && \
-    mv ./kubectl /usr/local/bin/kubectl
+
+# install some basic packages needed for testing, etc.
+RUN apk update && apk add bash curl sudo jq git make netcat-openbsd
+
+# install kubectl to interact with the k3d cluster
+RUN curl -L https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/linux/amd64/kubectl -o /usr/local/bin/kubectl && \
+    chmod +x /usr/local/bin/kubectl
+
+# install yq (yaml processor) from source, as the busybox yq had some issues
+RUN curl -L https://github.com/mikefarah/yq/releases/download/v4.9.6/yq_linux_amd64 -o /usr/bin/yq &&\
+    chmod +x /usr/bin/yq
 COPY --from=builder /app/bin/k3d /bin/k3d
 
+#########################################
+# binary-only                           #
+# -> only the k3d binary.. nothing else #
+#########################################
 FROM scratch as binary-only
 COPY --from=builder /app/bin/k3d /bin/k3d
 ENTRYPOINT ["/bin/k3d"]