A Bash script that uses OpenAI's API to generate a pull request title

pull-request-title

#!/usr/bin/env bash
#
# Print a title of the current pull request's commits.
#
# - For single commit pull requests, this prints the subject of the commit.
#
# - For multi-commit pull requests, this uses OpenAI's REST API to digest the
#   commit messages of the pull request into a single sentence.
#
# Requires an OPENAI_API_KEY env var to authenticate requests - see:
# https://beta.openai.com/docs/api-reference/authentication

set -e

# Commit selection variables.
TARGET_BRANCH=master

# OpenAI tuning variables (can be overridden by passing as env vars).
TEMPERATURE=${TEMPERATURE:-1}
MAX_TOKENS=${MAX_TOKENS:-512}
MODEL=${MODEL:-"text-davinci-002"}
INTRO=${INTRO:-"Below are some commit messages. Write a one sentence summary of them."}

function main {
    # How we generate the title depends on if there is more than one commit.
    if [ "$(num_commits)" -eq 1 ]; then
        single_commit_title
    else
        multi_commit_title
    fi
}

function num_commits {
    git log origin/$TARGET_BRANCH.. --oneline | wc -l
}

function single_commit_title {
    git log origin/$TARGET_BRANCH.. --format='%s' | head -1
}

function multi_commit_title {
    # Build the JSON payload.
    payload=$(jq -n \
        --arg model "$MODEL" \
        --argjson temp $TEMPERATURE \
        --argjson tokens $MAX_TOKENS \
        --arg prompt "$(
            echo "$INTRO"; 
            git log origin/$TARGET_BRANCH.. --format='%B';
            )" '{model: $model, temperature: $temp, max_tokens: $tokens, prompt: $prompt}'
    )

    # POST payload to OpenAI API.
    response=$(echo "$payload" | http https://api.openai.com/v1/completions Authorization:"Bearer $OPENAI_API_KEY")

    # Keep a copy of the payload and response for debugging.
    echo "$payload" | jq . > /tmp/openai-title.json
    echo "$response" | jq . >> /tmp/openai-title.json

    # Print the first line of the completion text.
    echo "$response" | jq -r '.choices[0].text' | sed '/./,$!d' | head -1
}

main