How to Use Antithesis

Context

Antithesis is a third party vendor with an environment that can perform network fuzzing. We can upload images containing docker-compose.yml files, which represent various MongoDB topologies, to the Antithesis Docker registry. Antithesis runs docker-compose up from these images to spin up the corresponding multi-container application in their environment and run a test suite. Network fuzzing is performed on the topology while the test suite runs & a report is generated by Antithesis identifying bugs. Check out https://github.com/mongodb/mongo/wiki/Testing-MongoDB-with-Antithesis to see an example of how we use Antithesis today.

Base Images

The base_images directory consists of the building blocks for creating a MongoDB test topology. These images are uploaded to the Antithesis Docker registry nightly during the antithesis image build and push function.

mongo_binaries

This image contains the latest mongo, mongos and mongod binaries. It can be used to start a mongod instance, mongos instance or execute mongo commands. This is the main building block for creating the System Under Test topology.

workload

This image contains the latest mongo binary as well as the resmoke test runner. The workload container is not part of the actual toplogy. The purpose of a workload container is to execute mongo commands to complete the topology setup, and to run a test suite on an existing topology like so:

buildscript/resmoke.py run --suite antithesis_concurrency_sharded_with_stepdowns_and_balancer

Every topology must have 1 workload container.

Note: During workload image build, evergreen/antithesis_image_build_and_push.sh runs, which generates "antithesis compatible" test suites and prepends them with antithesis_. These are the test suites that can run in antithesis and are available from within the workload container.

Dockerfile

This assembles an image with the necessary files for spinning up the corresponding topology. It consists of a docker-compose.yml, a logs directory, a scripts directory and a data directory. If this is structured properly, you should be able to copy the files & directories from this image and run docker-compose up to set up the desired topology.

Example from what buildscripts/resmokelib/testing/docker_cluster_image_builder.py generates:

FROM scratch
COPY docker-compose.yml /
ADD scripts /scripts
ADD logs /logs
ADD data /data
ADD debug /debug

All topology images are built and uploaded to the Antithesis Docker registry during the antithesis image build and push task. Some of these directories are created during the evergreen/antithesis_image_build_and_push.sh script such as /data and /logs.

Note: These images serve solely as a filesystem containing all necessary files for a topology, therefore use FROM scratch.

docker-compose.yml

This describes how to construct the corresponding topology using the mongo-binaries and workload images.

Example from buildscripts/antithesis/topologies/sharded_cluster/docker-compose.yml:

version: '3.0'

services:
        configsvr1:
                container_name: configsvr1
                hostname: configsvr1
                image: mongo-binaries:evergreen-latest-master
                volumes:
                  - ./logs/configsvr1:/var/log/mongodb/
                  - ./scripts:/scripts/
                  - ./data/configsvr1:/data/configdb/
                command: /bin/bash /scripts/configsvr_init.sh
                networks:
                        antithesis-net:
                                ipv4_address: 10.20.20.6
                                # Set the an IPv4 with an address of 10.20.20.130 or higher
                                # to be ignored by the fault injector
                                #

        configsvr2: ...
        configsvr3: ...
        database1: ...
                container_name: database1
                hostname: database1
                image: mongo-binaries:evergreen-latest-master
                volumes:
                  - ./logs/database1:/var/log/mongodb/
                  - ./scripts:/scripts/
                  - ./data/database1:/data/db/
                command: /bin/bash /scripts/database_init.sh Shard1
                networks:
                        antithesis-net:
                                ipv4_address: 10.20.20.3
                                # Set the an IPv4 with an address of 10.20.20.130 or higher
                                # to be ignored by the fault injector
                                #
        database2: ...
        database3: ...
        database4: ...
        database5: ...
        database6: ...
        mongos:
                container_name: mongos
                hostname: mongos
                image: mongo-binaries:evergreen-latest-master
                volumes:
                  - ./logs/mongos:/var/log/mongodb/
                  - ./scripts:/scripts/
                command: python3 /scripts/mongos_init.py
                depends_on:
                        - "database1"
                        - "database2"
                        - "database3"
                        - "database4"
                        - "database5"
                        - "database6"
                        - "configsvr1"
                        - "configsvr2"
                        - "configsvr3"
                networks:
                        antithesis-net:
                                ipv4_address: 10.20.20.9
                                # The subnet provided here is an example
                                # An alternative subnet can be used
        workload:
                container_name: workload
                hostname: workload
                image: workload:evergreen-latest-master
                volumes:
                  - ./logs/workload:/var/log/resmoke/
                  - ./scripts:/scripts/
                command: python3 /scripts/workload_init.py
                depends_on:
                        - "mongos"
                networks:
                        antithesis-net:
                                ipv4_address: 10.20.20.130
                                # The subnet provided here is an example
                                # An alternative subnet can be used
networks:
        antithesis-net:
                driver: bridge
                ipam:
                        config:
                        - subnet: 10.20.20.0/24

Each container must have a command in docker-compose.yml that runs an init script. The init script belongs in the scripts directory, which is included as a volume. The command should be set like so: /bin/bash /scripts/[script_name].sh or python3 /scripts/[script_name].py. This is a requirement for the topology to start up properly in Antithesis.

When creating mongod or mongos instances, route the logs like so: --logpath /var/log/mongodb/mongodb.log and utilize volumes -- as in database1. This enables us to easily retrieve logs if a bug is detected by Antithesis.

The ipv4_address should be set to 10.20.20.130 or higher if you do not want that container to be affected by network fuzzing. For instance, you would likely not want the workload container
to be affected by network fuzzing -- as shown in the example above.

Use the evergreen-latest-master tag for all images. This is updated automatically in evergreen/antithesis_image_build_and_push.sh -- if needed.

scripts

Take a look at buildscripts/antithesis/topologies/sharded_cluster/scripts/mongos_init.py to see how to use util methods from buildscripts/antithesis/topologies/sharded_cluster/scripts/utils.py to set up the desired topology. You can also use simple shell scripts as in the case of buildscripts/antithesis/topologies/sharded_cluster/scripts/database_init.py. These init scripts must not end in order to keep the underlying container alive. You can use an infinite while loop for python scripts or you can use tail -f /dev/null for shell scripts.

How do I create a new topology for Antithesis testing?

This should be done with care to ensure we are using our limited resources efficiently.

Create a new task extending the antithesis_task_template, tagged with antithesis, passing the specified suite to the antithesis image build and push task. See other examples to get started.

Additional Resources

If you are interested in leveraging Antithesis feel free to reach out to #server-testing on Slack.