Fix linter warnings in Cloud SDK-related images (#73)

Author: fwilhe

cf-cli/Dockerfile

@@ -2,6 +2,9 @@ FROM buildpack-deps:stretch-curl
 
 ENV VERSION 0.1
 
+# https://github.com/hadolint/hadolint/wiki/DL4006
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
+
 # ps needs to be available to be able to be used in docker.inside, see https://issues.jenkins-ci.org/browse/JENKINS-40101
 RUN apt-get update && \
     apt-get install -y --no-install-recommends procps && \
@@ -10,12 +13,13 @@ RUN apt-get update && \
 # add group & user
 RUN addgroup -gid 1000 piper && \
     useradd piper --uid 1000 --gid 1000 --shell /bin/bash --create-home && \
-    curl -L --silent "https://cli.run.pivotal.io/stable?release=linux64-binary&source=github" | tar -zx -C /usr/local/bin && \
+    curl --location --silent "https://cli.run.pivotal.io/stable?release=linux64-binary&source=github" | tar -zx -C /usr/local/bin && \
     cf --version
 
 USER piper
 WORKDIR /home/piper
 
+# hadolint ignore=DL4001
 RUN cf add-plugin-repo CF-Community https://plugins.cloudfoundry.org \
     && cf install-plugin blue-green-deploy -f -r CF-Community \
     && wget --quiet "https://github.com/cloudfoundry-incubator/multiapps-cli-plugin/releases/download/v2.0.13/mta_plugin_linux_amd64" \

jenkins-agent/Dockerfile

@@ -1,7 +1,10 @@
 FROM openjdk:8-jre-slim
 
 ENV JENKINS_HOME /var/jenkins_home
-  
+
+# https://github.com/hadolint/hadolint/wiki/DL4006
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
+
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
         git \
@@ -18,7 +21,7 @@ RUN apt-get update && \
        $(lsb_release -cs) \
        stable" && \
     apt-get update && \
-    apt-get -y install docker-ce && \
+    apt-get -y --no-install-recommends install docker-ce && \
     rm -rf /var/lib/apt/lists/* /var/cache/apt/*
 
 # add group & user

jenkins-master/Dockerfile

@@ -6,6 +6,9 @@ COPY init_jenkins.groovy /usr/share/jenkins/ref/init.groovy.d/init_jenkins.groov
 COPY plugins.txt /usr/share/jenkins/ref/plugins.txt
 COPY launch-jenkins-agent.sh /usr/share/jenkins/ref/launch-jenkins-agent.sh.override
 
+# https://github.com/hadolint/hadolint/wiki/DL4006
+SHELL ["/bin/bash", "-o", "pipefail", "-c"]
+
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
         apt-transport-https \

jenkinsfile-runner/Dockerfile

@@ -1,5 +1,9 @@
+# Inhereting form 'latest' Jenkins master is ok since this image is controlled by us
+# hadolint ignore=DL3006
 FROM ppiper/jenkins-master
 
+# User needs to be root for access to mounted Docker socket
+# hadolint ignore=DL3002
 USER root
 RUN curl -O https://repo.jenkins-ci.org/releases/io/jenkins/jenkinsfile-runner/jenkinsfile-runner/1.0-beta-7/jenkinsfile-runner-1.0-beta-7-app.zip && \
     unzip jenkinsfile-runner-1.0-beta-7-app.zip -d jenkinsfile-runner && \

node-browsers/Dockerfile

@@ -1,7 +1,7 @@
 FROM node:stretch
 
 RUN apt-get update && \
-    apt-get install -y chromium firefox-esr xvfb libxi6 libgconf-2-4 default-jre && \
+    apt-get install -y --no-install-recommends chromium firefox-esr xvfb libxi6 libgconf-2-4 default-jre && \
     rm -rf /var/lib/apt/lists/* /var/cache/apt/*
 
 RUN ln -s /usr/bin/chromium /usr/bin/google-chrome