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Aug. 17, 2018
Jan. 29, 2018

Minigo: A minimalist Go engine modeled after AlphaGo Zero, built on MuGo

This is a pure Python implementation of a neural-network based Go AI, using TensorFlow. While inspired by DeepMind's AlphaGo algorithm, this project is not a DeepMind project nor is it affiliated with the official AlphaGo project.

This is NOT an official version of AlphaGo

Repeat, this is not the official AlphaGo program by DeepMind. This is an independent effort by Go enthusiasts to replicate the results of the AlphaGo Zero paper ("Mastering the Game of Go without Human Knowledge," Nature), with some resources generously made available by Google.

Minigo is based off of Brian Lee's "MuGo" -- a pure Python implementation of the first AlphaGo paper "Mastering the Game of Go with Deep Neural Networks and Tree Search" published in Nature. This implementation adds features and architecture changes present in the more recent AlphaGo Zero paper, "Mastering the Game of Go without Human Knowledge". More recently, this architecture was extended for Chess and Shogi in "Mastering Chess and Shogi by Self-Play with a General Reinforcement Learning Algorithm". These papers will often be abridged in Minigo documentation as AG (for AlphaGo), AGZ (for AlphaGo Zero), and AZ (for AlphaZero) respectively.

Goals of the Project

  1. Provide a clear set of learning examples using Tensorflow, Kubernetes, and Google Cloud Platform for establishing Reinforcement Learning pipelines on various hardware accelerators.

  2. Reproduce the methods of the original DeepMind AlphaGo papers as faithfully as possible, through an open-source implementation and open-source pipeline tools.

  3. Provide our data, results, and discoveries in the open to benefit the Go, machine learning, and Kubernetes communities.

An explicit non-goal of the project is to produce a competitive Go program that establishes itself as the top Go AI. Instead, we strive for a readable, understandable implementation that can benefit the community, even if that means our implementation is not as fast or efficient as possible.

While this product might produce such a strong model, we hope to focus on the process. Remember, getting there is half the fun. :)

We hope this project is an accessible way for interested developers to have access to a strong Go model with an easy-to-understand platform of python code available for extension, adaptation, etc.

If you'd like to read about our experiences training models, see

To see our guidelines for contributing, see

Getting Started

This project assumes you have the following:

  • virtualenv / virtualenvwrapper
  • Python 3.5+
  • Docker
  • Cloud SDK
  • Bazel v0.11 or greater

The Hitchhiker's guide to python has a good intro to python development and virtualenv usage. The instructions after this point haven't been tested in environments that are not using virtualenv.

pip3 install virtualenv
pip3 install virtualenvwrapper

Install TensorFlow

First set up and enter your virtualenv and then the shared requirements:

pip3 install -r requirements.txt

Then, you'll need to choose to install the GPU or CPU tensorflow requirements:

  • GPU: pip3 install "tensorflow-gpu>=1.9,<1.10".
    • Note: You must install CUDA 9.0. for Tensorflow 1.5+.
  • CPU: pip3 install "tensorflow>=1.9,<1.10".

Setting up the Environment

You may want to use a cloud project for resources. If so set:


Then, running

source cluster/

will set up other environment variables defaults.

Running unit tests


Automated Tests

Test Dashboard

To automatically test PRs, Minigo uses Prow, which is a test framework created by the Kubernetes team for testing changes in a hermetic environment. We use prow for running unit tests, linting our code, and launching our test Minigo Kubernetes clusters.

You can see the status of our automated tests by looking at the Prow and Testgrid UIs:


All commands are compatible with either Google Cloud Storage as a remote file system, or your local file system. The examples here use GCS, but local file paths will work just as well.

To use GCS, set the BUCKET_NAME variable and authenticate via gcloud login. Otherwise, all commands fetching files from GCS will hang.

For instance, this would set a bucket, authenticate, and then look for the most recent model.

# When you first start we reccomend using our minigo-pub bucket.
# Later you can setup your own bucket and store data there.
export BUCKET_NAME=minigo-pub/v9-19x19
gcloud auth application-default login
gsutil ls gs://$BUCKET_NAME/models | tail -4

Which might look like:


These four files comprise the model. Commands that take a model as an argument usually need the path to the model basename, e.g. gs://$BUCKET_NAME/models/000737-fury

You'll need to copy them to your local disk. This fragment copies the files associated with $MODEL_NAME to the directory specified by MINIGO_MODELS

gsutil ls gs://$BUCKET_NAME/models | grep $MODEL_NAME | gsutil cp -I $MINIGO_MODELS


To watch Minigo play a game, you need to specify a model. Here's an example to play using the latest model in your bucket

python selfplay --num_readouts=$READOUTS -v 2

where READOUTS is how many searches to make per move. Timing information and statistics will be printed at each move. Setting verbosity (-v) to 3 or higher will print a board at each move.

Playing Against Minigo

Minigo uses the GTP Protocol, and you can use any gtp-compliant program with it.

# Latest model should look like: /path/to/models/000123-something
LATEST_MODEL=$(ls -d $MINIGO_MODELS/* | tail -1 | cut -f 1 -d '.')
BOARD_SIZE=19 python3 --load_file=$LATEST_MODEL --num_readouts=$READOUTS --verbose=3

After some loading messages, it will display GTP engine ready, at which point it can receive commands. GTP cheatsheet:

genmove [color]             # Asks the engine to generate a move for a side
play [color] [coordinate]   # Tells the engine that a move should be played for `color` at `coordinate`
showboard                   # Asks the engine to print the board.

One way to play via GTP is to use gogui-display (which implements a UI that speaks GTP.) You can download the gogui set of tools at See also documentation on interesting ways to use GTP.

gogui-twogtp -black 'python3 --load_file=$LATEST_MODEL' -white 'gogui-display' -size 19 -komi 7.5 -verbose -auto

Another way to play via GTP is to watch it play against GnuGo, while spectating the games

BLACK="gnugo --mode gtp"
WHITE="python3 --load_file=$LATEST_MODEL"
TWOGTP="gogui-twogtp -black \"$BLACK\" -white \"$WHITE\" -games 10 \
  -size 19 -alternate -sgffile gnugo"
gogui -size 19 -program "$TWOGTP" -computer-both -auto

Training Minigo


The following sequence of commands will allow you to do one iteration of reinforcement learning on 9x9. These are the basic commands used to produce the models and games referenced above.

The commands are

  • bootstrap: initializes a random model
  • selfplay: plays games with the latest model, producing data used for training
  • train: trains a new model with the selfplay results from the most recent N generations.

Training works via tf.Estimator; a local directory keeps track of training progress, and the latest checkpoint is periodically exported to GCS, where it gets picked up by selfplay workers.


This command initializes your working directory for the trainer and a random model. This random model is also exported to --model-save-path so that selfplay can immediately start playing with this random model.

If these directories don't exist, bootstrap will create them for you.

export MODEL_NAME=000000-bootstrap
python3 bootstrap \
  --working-dir=estimator_working_dir \


This command starts self-playing, outputting its raw game data in a tensorflow-compatible format as well as in SGF form in the directories

gsutil ls gs://$BUCKET_NAME/data/selfplay/$MODEL_NAME/local_worker/*.tfrecord.zz
gsutil ls gs://$BUCKET_NAME/sgf/$MODEL_NAME/local_worker/*.sgf
BOARD_SIZE=19 python3 \
  --load_file=gs://$BUCKET_NAME/models/$MODEL_NAME \
  --num_readouts 10 \
  --verbose 3 \
  --selfplay_dir=gs://$BUCKET_NAME/data/selfplay/$MODEL_NAME/local_worker \
  --holdout_dir=gs://$BUCKET_NAME/data/selfplay/$MODEL_NAME/local_worker \


This command takes a directory of tfexample files from selfplay and trains a new model, starting from the latest model weights in the estimator_working_dir parameter.

Run the training job:

BOARD_SIZE=19 python3 train-dir \
  gs://$BUCKET_NAME/data/training_chunks \
  gs://$BUCKET_NAME/models/000001-somename \
  --model_dir estimator_working_dir

At the end of training, the latest checkpoint will be exported to the directory with the given name. Additionally, you can follow along with the training progress with TensorBoard - if you point TensorBoard at the estimator working dir, it will find the training log files and display them.

tensorboard --logdir=estimator_working_dir


It can be useful to set aside some games to use as a 'validation set' for tracking the model overfitting. One way to do this is with the validate command.

Validating on holdout data

By default, Minigo will hold out 5% of selfplay games for validation, and write them to gs://$BUCKET_NAME/data/holdout/<model_name>. This can be changed by adjusting the holdout_pct flag on the selfplay command.

With this setup, python validate --logdir=estimator_working_dir -- will figure out the most recent model, grab the holdout data from the fifty models prior to that one, and calculate the validation error, writing the tensorboard logs to logdir.

Validating on a different set of data

This might be useful if you have some known set of 'good data' to test your network against, e.g., a set of pro games. Assuming you've got a set of .sgfs with the proper komi & boardsizes, you'll want to preprocess them into the .tfrecord files, by running something similar to

import preprocessing
filenames = [generate a list of filenames here]
for f in filenames:
         preprocessing.make_dataset_from_sgf(f, f.replace(".sgf", ".tfrecord.zz"))

Once you've collected all the files in a directory, producing validation is as easy as

BOARD_SIZE=19 python validate path/to/validation/files/ --load_file=$LATEST_MODEL
--logdir=path/to/tb/logs --num-steps=<number of positions to run validation on>

the validate command will glob all the .tfrecord.zz files under the directories given as positional arguments and compute the validation error for num_steps * TRAINING_BATCH_SIZE positions from those files.

Running Minigo on a Kubernetes Cluster

See more at cluster/

Latest Releases
 Jan. 29 2018