Github user GJL commented on a diff in the pull request:
https://github.com/apache/flink/pull/6239#discussion_r199622404
--- Diff: jepsen-flink/README.md ---
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+# jepsen.flink
+
+A Clojure project based on the
[Jepsen](https://github.com/jepsen-io/jepsen) framework to find bugs in the
+distributed coordination of Apache Flink®.
+
+## Test Coverage
+Jepsen is a framework built to test the behavior of distributed systems
+under faults. The tests in this particular project deploy Flink on either
YARN or Mesos, submit a
+job, and examine the availability of the job after injecting faults.
+A job is said to be available if all the tasks of the job are running.
+The faults that can be currently introduced to the Flink cluster include:
+* Killing of TaskManager/JobManager processes
+* Stopping HDFS NameNode
+* Network partitions
+
+There are many more properties other than job availability that could be
+verified but are not yet covered by this test suite, e.g., end-to-end
exactly-once processing
+semantics.
+
+## Usage
+See the [Jepsen
documentation](https://github.com/jepsen-io/jepsen#setting-up-a-jepsen-environment)
+for how to set up the environment to run tests. The `scripts/run-tests.sh`
documents how to invoke
+tests. The Flink job used for testing is located under
+`flink-end-to-end-tests/flink-datastream-allround-test`. You have to build
the job first and copy
+the resulting jar (`DataStreamAllroundTestProgram.jar`) to the `./bin`
directory of this project's
+root.
+
+To simplify development, we have prepared Dockerfiles and a Docker Compose
template
+so that you can run the tests locally in containers. To build the images
+and start the containers, simply run:
+
+ $ cd docker
+ $ ./up.sh
+
+After the containers started, open a new terminal window and run `docker
exec -it jepsen-control bash`.
+This will allow you to run arbitrary commands on the control node.
+To start the tests, you can use the `run-tests.sh` script in the `docker`
directory,
+which expects the number of test iterations, and a URI to a Flink
distribution, e.g.,
+
+ ./docker/run-tests.sh 1 https://example.com/flink-dist.tgz
+
+The project's root is mounted as a volume to all containers under the path
`/jepsen`.
+This means that changes to the test sources are immediately reflected in
the control node container.
+Moreover, this allows you to test locally built Flink distributions by
copying the tarball to the
+project's root and passing a URI with the `file://` scheme to the
`run-tests.sh` script, e.g.,
+`file:///jepsen/flink-dist.tgz`.
+
+### Checking the output of tests
+
+Consult the `jepsen.log` file for the particular test run in the `store`
folder. The final output of every test will be either
+
+ Everything looks good! ã½('ã¼`)ã
+
+or
+
+ Analysis invalid! (ï¾à²¥çಥï¼ï¾ â»ââ»
--- End diff --
it's a "flipping table emoji"
---
