jenkins docker plugin job "Permission denied" error
<p>I've got a CI environment on an Ubuntu 14.04 machine, setup with Jenkins, Gitlab and docker runtime installed. I configured a project myproject-hello-world (a java/maven project) and a corresponding jenkins job, consisting in the invocation of the following target </p>

<pre><code>(in Jenkins &gt; myproject-hello-world job configuration page)

Invoke top-level Maven targets
clean package docker:build -DskipTests
</code></pre>

<p>The jenkins job fails with the following error:</p>

<pre><code>[ERROR] Failed to execute goal com.spotify:docker-maven-plugin:0.2.3:build (default-cli) on project myproject-hello-world:
    Exception caught: java.util.concurrent.ExecutionException: com.spotify.docker.client.shaded.javax.ws.rs.ProcessingException: 
    org.newsclub.net.unix.AFUNIXSocketException: Permission denied (socket: /run/docker.sock) -&gt; [Help 1]

(see below for the whole console log)
</code></pre>

<p>If I leave only the <code>clean package</code> tasks for maven (that is, removing the docker:build plugin and leaving everything else unchanged), the project builds without problems, so I'm pretty sure my Jenkins+Jdk+Maven+Gitlab configuration shouldn't have any problems.</p>

<p>Also, If I launch on my development machine <code>mvn clean package docker:build</code>, this works as well, correctly creating a docker image for my project. This should exclude problems in the docker-maven plugin configuration in pom.xml or my Dockerfile.</p>

<p>This is how the Jekins Docker plugin is configured in Jenkins Configuration > System Configuration > Cloud / Add Cloud: Docker section I have put the following config</p>

<pre><code>Name
docker

Docker URL
http://localhost:4243

Credentials:
None
</code></pre>

<p>Not clear whether I have to put something in the "Credentials" section (could be relevant being the problem a "Permission denied" error, but in case I've no idea of what credentials I should put here)    </p>

<p>This is the whole job's console output</p>

<pre><code>Started by user ...
Building in workspace /var/lib/jenkins/workspace/myproject-hello-world mvn docker build
 &gt; git rev-parse --is-inside-work-tree # timeout=10
Fetching changes from the remote Git repository
 &gt; git config remote.origin.url http://myproject.repository:8082/&lt;my username&gt;/myproject-hello-world.git # timeout=10
Fetching upstream changes from http://myproject.repository:8082/&lt;my username&gt;/myproject-hello-world.git
 &gt; git --version # timeout=10
using .gitcredentials to set credentials
 &gt; git config --local credential.username &lt;my username&gt; # timeout=10
 &gt; git config --local credential.helper store --file=/tmp/git4397825852307959267.credentials # timeout=10
 &gt; git -c core.askpass=true fetch --tags --progress http://myproject.repository:8082/&lt;my username&gt;/myproject-hello-world.git +refs/heads/*:refs/remotes/origin/*
 &gt; git config --local --remove-section credential # timeout=10
 &gt; git rev-parse refs/remotes/origin/master^{commit} # timeout=10
 &gt; git rev-parse refs/remotes/origin/origin/master^{commit} # timeout=10
Checking out Revision 456503c176851863d8398df83385305687aef9b3 (refs/remotes/origin/master)
 &gt; git config core.sparsecheckout # timeout=10
 &gt; git checkout -f 456503c176851863d8398df83385305687aef9b3
 &gt; git rev-list 456503c176851863d8398df83385305687aef9b3 # timeout=10
[myproject-hello-world mvn docker build] $ mvn clean package docker:build -DskipTests
[INFO] Scanning for projects...
[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building myproject-hello-world 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-clean-plugin:2.5:clean (default-clean) @ myproject-hello-world ---
[INFO] Deleting /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ myproject-hello-world ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO] Copying 0 resource
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ myproject-hello-world ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 2 source files to /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target/classes
[INFO] 
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ myproject-hello-world ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/src/test/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ myproject-hello-world ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:2.18.1:test (default-test) @ myproject-hello-world ---
[INFO] Tests are skipped.
[INFO] 
[INFO] --- maven-jar-plugin:2.5:jar (default-jar) @ myproject-hello-world ---
[INFO] Building jar: /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target/myproject-hello-world.jar
[INFO] 
[INFO] --- spring-boot-maven-plugin:1.3.3.RELEASE:repackage (default) @ myproject-hello-world ---
[INFO] 
[INFO] --- docker-maven-plugin:0.2.3:build (default-cli) @ myproject-hello-world ---
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[INFO] Copying /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target/myproject-hello-world.jar -&gt; /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target/docker/myproject-hello-world.jar
[INFO] Copying src/main/docker/Dockerfile -&gt; /var/lib/jenkins/workspace/myproject-hello-world mvn docker build/target/docker/Dockerfile
[INFO] Building image myproject-h2020/myproject-hello-world:0.0.1-SNAPSHOT
May 10, 2016 1:34:39 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (org.newsclub.net.unix.AFUNIXSocketException) caught when processing request to {}-&gt;unix://localhost:80: Permission denied
May 10, 2016 1:34:39 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}-&gt;unix://localhost:80
May 10, 2016 1:34:39 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (org.newsclub.net.unix.AFUNIXSocketException) caught when processing request to {}-&gt;unix://localhost:80: Permission denied
May 10, 2016 1:34:39 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}-&gt;unix://localhost:80
May 10, 2016 1:34:39 PM org.apache.http.impl.execchain.RetryExec execute
INFO: I/O exception (org.newsclub.net.unix.AFUNIXSocketException) caught when processing request to {}-&gt;unix://localhost:80: Permission denied
May 10, 2016 1:34:39 PM org.apache.http.impl.execchain.RetryExec execute
INFO: Retrying request to {}-&gt;unix://localhost:80
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 11.626s
[INFO] Finished at: Tue May 10 13:34:39 UTC 2016
[INFO] Final Memory: 27M/64M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal com.spotify:docker-maven-plugin:0.2.3:build (default-cli) on project myproject-hello-world: Exception caught: java.util.concurrent.ExecutionException: com.spotify.docker.client.shaded.javax.ws.rs.ProcessingException: org.newsclub.net.unix.AFUNIXSocketException: Permission denied (socket: /run/docker.sock) -&gt; [Help 1]
[ERROR] 
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR] 
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
Build step 'Invoke top-level Maven targets' marked build as failure
Finished: FAILURE
</code></pre>

<p>in the docker plugin instruction page at <a href="https://wiki.jenkins-ci.org/display/JENKINS/Docker+Plugin" rel="nofollow">https://wiki.jenkins-ci.org/display/JENKINS/Docker+Plugin</a> there is a hint that I have to set </p>

<pre><code>DOCKER_OPTS="-H tcp://0.0.0.0:4243 -H unix:///var/run/docker.sock"
</code></pre>

<p>in /etc/default/docker file. I did it but nothing changed.</p>