[jira] [Created] (FLINK-3441) Revisit quickstarts exclusion policy

["Till Rohrmann (JIRA)" <ji...@apache.org>]

Till Rohrmann created FLINK-3441:
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             Summary: Revisit quickstarts exclusion policy
                 Key: FLINK-3441
                 URL: https://issues.apache.org/jira/browse/FLINK-3441
             Project: Flink
          Issue Type: Improvement
          Components: Quickstarts
    Affects Versions: 1.0.0
            Reporter: Till Rohrmann
            Priority: Minor


Flink provides quickstart projects to quickly set up a Flink project. In order to decrease the size of the resulting jar, the predefined {{pom.xml}} file contains a list of excluded dependencies.

The problem with this approach is two-fold: First of all, the list seems to be rather arbitrary. Why excluding {{org.apache.commons:commons-math}} but not {{org.apache.commons:commons-math3}}? It seems as if this list would have to be kept up to date with every changing dependency of Flink.

Secondly and the more severe problem is the following: The exclusions assume that Flink always provides a compatible version for an excluded dependency. However, since the exclusions are not bound to a specific version, this won't necessarily be true. For example, {{snappy-java}} is excluded from the user job jar, because Flink with Hadoop {{2.3.0}} comes with {{snappy-java:1.0.5}}. However, the {{kafka-clients:0.9.0}} which comes with the {{flink-connector-kafka-0.9}} dependency has a transitive dependency on {{snappy-java:1.1.1.7}}. Consequently, this dependency will be excluded from the user job jar per default. If version {{1.1.1.7}} is not compatible to {{snappy-java:1.0.5}}, then the program will crash at runtime. This will be very hard to understand for the user because it is a very subtle bug since the exclusions also affect the transitive dependencies.



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