Docker build failing

[eduardoroliveira]

Docker build failing while trying to create /opt folder:

===== docker-build ======
envsubst < Dockerfile | docker build --pull -t omnition/synthetic-load-generator:latest -f - .
Sending build context to Docker daemon 4.859MB
Step 1/8 : FROM openjdk:8-jre-alpine
8-jre-alpine: Pulling from library/openjdk
Digest: sha256:f362b165b870ef129cbe730f29065ff37399c0aa8bcab3e44b51c302938c9193
Status: Image is up to date for openjdk:8-jre-alpine
---> f7a292bbb70c
Step 2/8 : RUN mkdir /opt /opt/omnition /opt/omnition/topologies
---> Running in 4011e6c1627b
mkdir: can't create directory '/opt': File exists
The command '/bin/sh -c mkdir /opt /opt/omnition /opt/omnition/topologies' returned a non-zero code: 1
make: *** [docker-build] Error 1

XXXXXX
A detail that can be the reason is that I already had the docker image downloaded. I will post a change suggestion in Dockerfile to solve the problem.