<p>We've got a Java application that generates word documents using a 3rd party (Asposee but I don't think it matters here). The app is built from a simple Docker file:</p>

<pre><code>FROM openjdk:10-jdk-slim
COPY target/*.jar /opt/
CMD $JAVA_HOME/bin/java $JAVA_OPTS -jar /opt/*.jar
</code></pre>

<p>When we build the application locally (<code>mvn package</code> then <code>docker build</code>) and run the application inside <code>k8s</code> it works well.</p>

<p>However, when we build the image in our CI/CD pipeline with Jenkins we get a runtime exception when running through a specific process which apparently requires additional fonts:</p>

<pre><code>Caused by: java.lang.NullPointerException: null
    at java.desktop/sun.awt.FontConfiguration.getVersion(FontConfiguration.java:1288)
    at java.desktop/sun.awt.FontConfiguration.readFontConfigFile(FontConfiguration.java:225)
    at java.desktop/sun.awt.FontConfiguration.init(FontConfiguration.java:107)
    at java.desktop/sun.awt.X11FontManager.createFontConfiguration(X11FontManager.java:765)
    at java.desktop/sun.font.SunFontManager$2.run(SunFontManager.java:440)
    at java.base/java.security.AccessController.doPrivileged(Native Method)
    at java.desktop/sun.font.SunFontManager.&lt;init&gt;(SunFontManager.java:385)
    at java.desktop/sun.awt.FcFontManager.&lt;init&gt;(FcFontManager.java:35)
    at java.desktop/sun.awt.X11FontManager.&lt;init&gt;(X11FontManager.java:56)
</code></pre>

<p>In that case the project is buit in Jenkins, compiled by the docker image <code>maven:3.5.4-jdk-10-slim</code>.</p>

<p>I've checked both jar files (locally and from jenkins) and the class files are the same (as expected).</p>

<p>In both cases it's the same base image so I don't understand what could be the difference. Is something different in Docker when building locally vs inside another Docker container?</p>

<p><strong>EDIT</strong></p>

<p>We've looked into both docker images and found the following difference.</p>

<p>Since locally built image <code>ls -l /usr/lib</code> returns:</p>

<pre><code>drwxr-xr-x  2 root root  4096 May  3  2017 X11
drwxr-xr-x  5 root root  4096 Apr 26 00:00 apt
drwxr-xr-x  2 root root  4096 May 26 08:31 binfmt.d
drwxr-xr-x  2 root root  4096 Jun  6 01:50 cgmanager
drwxr-xr-x  2 root root  4096 Jun  6 01:50 dbus-1.0
drwxr-xr-x  2 root root  4096 Jun  6 01:51 dconf
drwxr-xr-x  3 root root  4096 Jun  6 01:51 debug
drwxr-xr-x  3 root root  4096 Apr 20 10:08 dpkg
drwxr-xr-x  2 root root  4096 Jun  6 01:50 environment.d
drwxr-xr-x  3 root root  4096 Apr 25 04:56 gcc
drwxr-xr-x  2 root root  4096 Jun  6 01:51 glib-networking
drwxr-xr-x  2 root root  4096 Apr 26 00:00 init
drwxr-xr-x  1 root root  4096 Jun  6 01:51 jvm
drwxr-xr-x  3 root root  4096 Jun  6 01:50 kernel
lrwxrwxrwx  1 root root    20 Mar  4 09:49 libnih-dbus.so.1 -&gt; libnih-dbus.so.1.0.0
-rw-r--r--  1 root root 34824 Mar  4 09:49 libnih-dbus.so.1.0.0
lrwxrwxrwx  1 root root    15 Mar  4 09:49 libnih.so.1 -&gt; libnih.so.1.0.0
-rw-r--r--  1 root root 92184 Mar  4 09:49 libnih.so.1.0.0
drwxr-xr-x  3 root root  4096 Mar 29 19:47 locale
drwxr-xr-x  3 root root  4096 Jun  6 01:50 lsb
drwxr-xr-x  1 root root  4096 Jul 21  2017 mime
drwxr-xr-x  2 root root  4096 Jun  6 01:50 modprobe.d
drwxr-xr-x  2 root root  4096 May 26 08:31 modules-load.d
-rw-r--r--  1 root root   198 Jan 13 23:36 os-release
drwxr-xr-x  3 root root  4096 Jun  6 01:51 ssl
drwxr-xr-x  1 root root  4096 Jun  6 01:50 systemd
drwxr-xr-x  2 root root  4096 Jun  6 01:50 sysusers.d
drwxr-xr-x  2 root root  4096 Jul 21  2017 tar
drwxr-xr-x 15 root root  4096 Feb 11 20:06 terminfo
drwxr-xr-x  1 root root  4096 Jun  6 01:50 tmpfiles.d
drwxr-xr-x  1 root root  4096 Apr 26 00:00 udev
drwxr-xr-x  1 root root 16384 Jun  6 01:51 x86_64-linux-gnu
</code></pre>

<p>But inside Jenkins built image <code>ls -l /usr/lib</code> returns:</p>

<pre><code>drwxr-xr-x  5 root root 4096 Jun 25 00:00 apt
drwxr-xr-x  3 root root 4096 Jul  3 01:00 debug
drwxr-xr-x  3 root root 4096 Apr 20 10:08 dpkg
drwxr-xr-x  3 root root 4096 Jun 17 03:36 gcc
drwxr-xr-x  2 root root 4096 Jun 25 00:00 init
drwxr-xr-x  1 root root 4096 Jul  3 01:00 jvm
drwxr-xr-x  1 root root 4096 Jul 12 11:00 locale
drwxr-xr-x  3 root root 4096 Jul  3 01:00 lsb
drwxr-xr-x  1 root root 4096 May 16 07:47 mime
-rw-r--r--  1 root root  198 Jan 13 23:36 os-release
drwxr-xr-x  3 root root 4096 Jul  3 01:00 ssl
drwxr-xr-x  3 root root 4096 Apr 20 10:08 systemd
drwxr-xr-x  2 root root 4096 May 16 07:47 tar
drwxr-xr-x 15 root root 4096 May 21 08:54 terminfo
drwxr-xr-x  2 root root 4096 Jun 25 00:00 tmpfiles.d
drwxr-xr-x  3 root root 4096 Jun 25 00:00 udev
drwxr-xr-x  2 root root 4096 May  3  2017 X11
drwxr-xr-x  1 root root 4096 Jul  3 01:00 x86_64-linux-gnu
</code></pre>

<p>This is really puzzling as I thought Docker would always produce the same image from identical Dockerfiles</p>

<p>With openjdk:8u111-jdk-alpine, installing dejavu fix the problem:</p>
<p>For example:</p>
<p>Dockerfile:</p>
<pre><code>FROM openjdk:8u111-jdk-alpine
# Needed to fix 'Fontconfig warning: ignoring C.UTF-8: not a valid language tag'
ENV LANG en_GB.UTF-8

# JRE fails to load fonts if there are no standard fonts in the image; DejaVu is a good choice,
# see https://github.com/docker-library/openjdk/issues/73#issuecomment-207816707
RUN apk add --update ttf-dejavu &amp;&amp; rm -rf /var/cache/apk/*

VOLUME /tmp
COPY /target/*.jar app.jar
ENTRYPOINT [&quot;java&quot;,&quot;-Xmx100m&quot;,&quot;-Djava.security.egd=file:/dev/./urandom&quot;,&quot;-jar&quot;,&quot;/app.jar&quot;]
</code></pre>
