NPE when logging to file

[hho]

Description

When logging to a file and starting a container early in the build, a NullPointerException is thrown:

Exception in thread "Thread-1" java.lang.NullPointerException
	at io.fabric8.maven.docker.log.DefaultLogCallback.ps(DefaultLogCallback.java:74)
	at io.fabric8.maven.docker.log.DefaultLogCallback.error(DefaultLogCallback.java:84)
	at io.fabric8.maven.docker.access.log.LogRequestor.run(LogRequestor.java:110)

Info

• d-m-p version: 0.23.0
• Maven version (mvn -v):

Apache Maven 3.5.2 (138edd61fd100ec658bfa2d307c43b76940a5d7d; 2017-10-18T09:58:13+02:00)
Maven home: /home/hho/.sdkman/candidates/maven/current
Java version: 1.8.0_151, vendor: Oracle Corporation
Java home: /usr/lib/jvm/java-8-oracle/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "4.13.0-19-generic", arch: "amd64", family: "unix"

• Docker version: 17.11.0-ce
• If it's a bug, how to reproduce:
  1. Use the POM given below
  2. run mvn compile

POM to reproduce

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>demo</groupId>
  <artifactId>npedemo</artifactId>
  <version>1.0-SNAPSHOT</version>
  <build>
    <plugins>
      <plugin>
        <groupId>io.fabric8</groupId>
        <artifactId>docker-maven-plugin</artifactId>
        <version>0.23.0</version>
        <configuration>
          <images>
            <image>
              <name>postgres:alpine</name>
              <run>
                <log>
                  <file>${project.build.directory}/postgres.log</file>
                </log>
              </run>
            </image>
          </images>
        </configuration>
        <executions>
          <execution>
            <id>start-db</id>
            <phase>generate-sources</phase>
            <goals><goal>start</goal></goals>
          </execution>
          <execution>
            <id>stop-db</id>
            <phase>generate-resources</phase>
            <goals><goal>stop</goal></goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

Example Build Output

➜ mvn compile
[INFO] Scanning for projects...
[INFO] 
[INFO] ------------------------------------------------------------------------
[INFO] Building npedemo 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- docker-maven-plugin:0.23.0:start (start-db) @ npedemo ---
[INFO] DOCKER> [postgres:alpine]: Start container 69f9e99da85e
Exception in thread "Thread-1" java.lang.NullPointerException
	at io.fabric8.maven.docker.log.DefaultLogCallback.ps(DefaultLogCallback.java:74)
	at io.fabric8.maven.docker.log.DefaultLogCallback.error(DefaultLogCallback.java:84)
	at io.fabric8.maven.docker.access.log.LogRequestor.run(LogRequestor.java:110)
[INFO] 
[INFO] --- docker-maven-plugin:0.23.0:stop (stop-db) @ npedemo ---
[INFO] DOCKER> [postgres:alpine]: Stop and removed container 69f9e99da85e after 0 ms
[INFO] 
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ npedemo ---
[WARNING] Using platform encoding (UTF-8 actually) to copy filtered resources, i.e. build is platform dependent!
[INFO] skip non existing resourceDirectory /tmp/npedemo/src/main/resources
[INFO] 
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ npedemo ---
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding UTF-8, i.e. build is platform dependent!
[INFO] Compiling 1 source file to /tmp/npedemo/target/classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 12.681 s
[INFO] Finished at: 2017-12-14T17:28:47+01:00
[INFO] Final Memory: 21M/360M
[INFO] ------------------------------------------------------------------------

[rhuss]

Thanks, good finding. Indeed there can be a race and should be protected.