diff --git a/.eslintrc.json b/.eslintrc.json
new file mode 100644
index 0000000..43d51c6
--- /dev/null
+++ b/.eslintrc.json
@@ -0,0 +1,11 @@
+{
+  "env": {
+    "node": true
+  },
+  "extends": [
+    "@supercharge"
+  ],
+  "parserOptions": {
+    "ecmaVersion": 2018
+  }
+}
diff --git a/.github/workflows/actions_release.yml b/.github/workflows/actions_release.yml
new file mode 100644
index 0000000..6082ace
--- /dev/null
+++ b/.github/workflows/actions_release.yml
@@ -0,0 +1,21 @@
+name: Release GitHub Actions
+
+on:
+  workflow_dispatch:
+    inputs:
+      tag:
+        description: "Tag for the release"
+        required: true
+
+permissions:
+  contents: read
+
+jobs:
+  release:
+    permissions:
+      actions: read
+      id-token: write
+      contents: write
+    uses: step-security/reusable-workflows/.github/workflows/actions_release.yaml@v1
+    with:
+      tag: "${{ github.event.inputs.tag }}"
\ No newline at end of file
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..6d039fe
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,21 @@
+name: Start MongoDB Server
+
+on: [push, pull_request]
+
+jobs:
+  mongodb-action:
+    name: Start MongoDB Server v${{ matrix.mongodb-version }}
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        mongodb-version: ['4.0', '4.2', '4.4', '5.0', '6.0']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Start MongoDB Server
+        uses: ./
+        with:
+          mongodb-version: ${{ matrix.mongodb-version }}
diff --git a/.github/workflows/test-auth.yml b/.github/workflows/test-auth.yml
new file mode 100644
index 0000000..2423c28
--- /dev/null
+++ b/.github/workflows/test-auth.yml
@@ -0,0 +1,44 @@
+name: Single Instance With Auth
+
+on: [push, pull_request]
+
+jobs:
+  single-instance-with-auth:
+    name: Mongo v${{ matrix.mongodb-version }} - Node v${{ matrix.node-version }}
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [18, 20]
+        mongodb-version: ['4.4', '5.0', '6.0']
+        mongodb-db: ['ci']
+        mongodb-username: ['ci']
+        mongodb-password: ['ci']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Start MongoDB Server v${{ matrix.mongodb-version }}
+        uses: ./
+        with:
+          mongodb-version: ${{ matrix.mongodb-version }}
+          mongodb-db: ${{ matrix.mongodb-db }}
+          mongodb-username: ${{ matrix.mongodb-username }}
+          mongodb-password: ${{ matrix.mongodb-password }}
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test ./test/single-instance
+        env:
+          CI: true
+          MONGODB_DB: ${{ matrix.mongodb-db }}
+          MONGODB_USERNAME: ${{ matrix.mongodb-username }}
+          MONGODB_PASSWORD: ${{ matrix.mongodb-password }}
diff --git a/.github/workflows/test-replica-set.yml b/.github/workflows/test-replica-set.yml
new file mode 100644
index 0000000..87c6c35
--- /dev/null
+++ b/.github/workflows/test-replica-set.yml
@@ -0,0 +1,72 @@
+name: Replica Set Tests
+
+on: [push, pull_request]
+
+jobs:
+  single-node-replica-set-on-default-port:
+    name: MongoDB v${{ matrix.mongodb-version }} RS — Node.js v${{ matrix.node-version }}
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [18, 20]
+        mongodb-version: ['4.4', '5.0', '6.0']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Start MongoDB Server v${{ matrix.mongodb-version }}
+        uses: ./
+        with:
+          mongodb-version: ${{ matrix.mongodb-version }}
+          mongodb-replica-set: mongodb-test-rs
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test ./test/replica-set
+        env:
+          CI: true
+          MONGODB_REPLICA_SET: mongodb-test-rs
+
+  single-node-replica-set-on-custom-port:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [18, 20]
+        mongodb-port: [23456]
+        mongodb-version: ['4.4', '5.0', '6.0']
+
+    name: MongoDB v${{ matrix.mongodb-version }} RS, Port ${{ matrix.mongodb-port }} — Node.js v${{ matrix.node-version }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Start MongoDB Server v${{ matrix.mongodb-version }}
+        uses: ./
+        with:
+          mongodb-port: ${{ matrix.mongodb-port }}
+          mongodb-version: ${{ matrix.mongodb-version }}
+          mongodb-replica-set: mongodb-test-rs
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test ./test/replica-set
+        env:
+          CI: true
+          MONGODB_PORT: ${{ matrix.mongodb-port }}
+          MONGODB_REPLICA_SET: mongodb-test-rs
diff --git a/.github/workflows/test-single-instance.yml b/.github/workflows/test-single-instance.yml
new file mode 100644
index 0000000..56adff3
--- /dev/null
+++ b/.github/workflows/test-single-instance.yml
@@ -0,0 +1,69 @@
+name: Single Instance Tests
+
+on: [push, pull_request]
+
+jobs:
+  single-instance-on-default-port:
+    name: MongoDB v${{ matrix.mongodb-version }} — Node.js v${{ matrix.node-version }}
+
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [18, 20]
+        mongodb-version: ['4.4', '5.0', '6.0']
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Start MongoDB Server v${{ matrix.mongodb-version }}
+        uses: ./
+        with:
+          mongodb-version: ${{ matrix.mongodb-version }}
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test ./test/single-instance
+        env:
+          CI: true
+          MONGODB_DB: ${{ matrix.mongodb-db }}
+
+
+  single-instance-on-custom-port:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        mongodb-port: [12345]
+        mongodb-version: ['4.4', '5.0', '6.0']
+        node-version: [18, 20]
+
+    name: MongoDB v${{ matrix.mongodb-version }}, Port ${{ matrix.mongodb-port }} — Node.js v${{ matrix.node-version }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Start MongoDB Server v${{ matrix.mongodb-version }}
+        uses: ./
+        with:
+          mongodb-version: ${{ matrix.mongodb-version }}
+          mongodb-port: ${{ matrix.mongodb-port }}
+
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Install dependencies
+        run: npm install
+
+      - name: Run tests
+        run: npm test ./test/custom-port
+        env:
+          CI: true
diff --git a/.github/workflows/validate-action-typings.yml b/.github/workflows/validate-action-typings.yml
new file mode 100644
index 0000000..c984f93
--- /dev/null
+++ b/.github/workflows/validate-action-typings.yml
@@ -0,0 +1,14 @@
+name: Validate action typings
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  validate-typings:
+    runs-on: "ubuntu-latest"
+    steps:
+      - uses: actions/checkout@v4
+      - uses: krzema12/github-actions-typing@v1
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e5386f0
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,32 @@
+haters
+
+lib-cov
+*.seed
+*.log
+*.csv
+*.dat
+*.out
+*.pid
+*.gz
+.github-todos
+
+pids
+results
+
+node_modules
+npm-debug.log
+package-lock.json
+
+# code coverage folder
+coverage
+.nyc_output
+
+# Secrets
+.env
+.env.**
+
+# IDEs and editors
+.idea
+.vscode
+
+.vagrant
diff --git a/Dockerfile b/Dockerfile
new file mode 100644
index 0000000..6ec69d1
--- /dev/null
+++ b/Dockerfile
@@ -0,0 +1,4 @@
+FROM docker:stable
+COPY start-mongodb.sh /start-mongodb.sh
+RUN chmod +x /start-mongodb.sh
+ENTRYPOINT ["/start-mongodb.sh"]
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..45153da
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2023 StepSecurity
+Copyright (c) 2019 The Supercharge Node.js Framework
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/README.md b/README.md
index c7a1b5e..40bbad4 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,222 @@
-# mongodb-github-action
\ No newline at end of file
+
+## Introduction
+This GitHub Action starts a MongoDB server or MongoDB replica set. By default, the MongoDB server is available on the default port `27017`. You can configure a custom port using the `mongodb-port` input. The examples show how to use a custom port.
+
+The MongoDB version must be specified using the `mongodb-version` input. The used version must exist in the published [`mongo` Docker hub tags](https://hub.docker.com/_/mongo?tab=tags). Default value is `latest`, other popular choices are `6.0`, `7.0` or even release candidates `8.0.0-rc4`.
+
+This is useful when running tests against a MongoDB database.
+
+
+## Usage
+A code example says more than a 1000 words. Here’s an exemplary GitHub Action using a MongoDB server in different versions to test a Node.js app:
+
+```yaml
+name: Run tests
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20.x, 22.x]
+        mongodb-version: ['6.0', '7.0', '8.0']
+
+    steps:
+    - name: Git checkout
+      uses: actions/checkout@v4
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Start MongoDB
+      uses: step-security/mongodb-github-action@1.11.0
+      with:
+        mongodb-version: ${{ matrix.mongodb-version }}
+
+    - run: npm install
+
+    - run: npm test
+      env:
+        CI: true
+```
+
+
+### Using a Custom MongoDB Port
+You can start the MongoDB instance on a custom port. Use the `mongodb-port: 12345` input to configure port `12345` for MongoDB. Replace `12345` with the port you want to use in your test runs.
+
+The following example starts a MongoDB server on port `42069`:
+
+```yaml
+name: Run tests
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20.x, 22.x]
+        mongodb-version: ['6.0', '7.0', '8.0']
+
+    steps:
+    - name: Git checkout
+      uses: actions/checkout@v4
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Start MongoDB
+      uses: step-security/mongodb-github-action@1.11.0
+      with:
+        mongodb-version: ${{ matrix.mongodb-version }}
+        mongodb-replica-set: test-rs
+        mongodb-port: 42069
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Run tests
+      run: npm test
+      env:
+        CI: true
+```
+
+
+### With a Replica Set (MongoDB `--replSet` Flag)
+You can run your tests against a MongoDB replica set by adding the `mongodb-replica-set: your-replicate-set-name` input in your action’s workflow. The value for `mongodb-replica-set` defines the name of your replica set. Replace `your-replicate-set-name` with the replica set name you want to use in your tests.
+
+The following example uses the replica set name `test-rs`:
+
+```yaml
+name: Run tests
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20.x, 22.x]
+        mongodb-version: ['6.0', '7.0', '8.0']
+
+    steps:
+    - name: Git checkout
+      uses: actions/checkout@v4
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Start MongoDB
+      uses: step-security/mongodb-github-action@1.11.0
+      with:
+        mongodb-version: ${{ matrix.mongodb-version }}
+        mongodb-replica-set: test-rs
+        mongodb-port: 42069
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Run tests
+      run: npm test
+      env:
+        CI: true
+```
+
+
+### With Authentication (MongoDB `--auth` Flag)
+Setting the `mongodb-username` and `mongodb-password` inputs. As per the [Dockerhub documentation](https://hub.docker.com/_/mongo), this automatically creates an admin user and enables `--auth` mode.
+
+The following example uses the username `supercharge`, password `secret` and also sets an initial `supercharge` database:
+
+```yaml
+name: Run tests with authentication
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20.x, 22.x]
+        mongodb-version: ['6.0', '7.0', '8.0']
+
+    steps:
+    - name: Git checkout
+      uses: actions/checkout@v4
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Start MongoDB
+      uses: step-security/mongodb-github-action@1.11.0
+      with:
+        mongodb-version: ${{ matrix.mongodb-version }}
+        mongodb-username: supercharge
+        mongodb-password: secret
+        mongodb-db: supercharge
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Run tests
+      run: npm test
+      env:
+        CI: true
+```
+
+### With Custom Container Name
+The container name of the created MongoDB instance can be configured using the `mongodb-container-name` input
+
+The following example will parameterize the MongoDB container name based on the `node-version` and `mongodb-version` being used from the matrix:
+
+```yaml
+name: Run with Custom Container Names
+
+on: [push]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        node-version: [20.x, 22.x]
+        mongodb-version: ['6.0', '7.0', '8.0']
+
+    steps:
+    - name: Git checkout
+      uses: actions/checkout@v4
+
+    - name: Use Node.js ${{ matrix.node-version }}
+      uses: actions/setup-node@v4
+      with:
+        node-version: ${{ matrix.node-version }}
+
+    - name: Start MongoDB
+      uses: step-security/mongodb-github-action@1.11.0
+      with:
+        mongodb-version: ${{ matrix.mongodb-version }}
+        mongodb-container-name: mongodb-${{ matrix.node-version }}-${{ matrix.mongodb-version }}
+
+    - name: Install dependencies
+      run: npm install
+
+    - name: Run tests
+      run: npm test
+      env:
+        CI: true
+```
+
+**Caveat:** due to [this issue](https://github.com/docker-library/mongo/issues/211), you **cannot enable user creation AND replica sets** initially. Therefore, if you use this action to setup a replica set, please create your users through a separate script.
diff --git a/SECURITY.md b/SECURITY.md
new file mode 100644
index 0000000..77568b2
--- /dev/null
+++ b/SECURITY.md
@@ -0,0 +1,5 @@
+# Security Policy
+
+## Reporting a Vulnerability
+
+Please report security vulnerabilities to security@stepsecurity.io
diff --git a/action-types.yml b/action-types.yml
new file mode 100644
index 0000000..467fe41
--- /dev/null
+++ b/action-types.yml
@@ -0,0 +1,16 @@
+# See https://github.com/krzema12/github-actions-typing
+inputs:
+  mongodb-version:
+    type: string
+  mongodb-replica-set:
+    type: string
+  mongodb-port:
+    type: integer
+  mongodb-db:
+    type: string
+  mongodb-username:
+    type: string
+  mongodb-password:
+    type: string
+  mongodb-container-name:
+    type: string
diff --git a/action.yml b/action.yml
new file mode 100644
index 0000000..170e6a9
--- /dev/null
+++ b/action.yml
@@ -0,0 +1,54 @@
+name: 'MongoDB in GitHub Actions'
+description: 'Start a MongoDB server (on default port 27017 or a custom port)'
+
+branding:
+  icon: 'database'
+  color: 'green'
+
+inputs:
+  mongodb-version:
+    description: 'MongoDB version to use (default "latest")'
+    required: false
+    default: 'latest'
+
+  mongodb-replica-set:
+    description: 'MongoDB replica set name (no replica set by default)'
+    required: false
+    default: ''
+
+  mongodb-port:
+    description: 'MongoDB port to use (default 27017)'
+    required: false
+    default: 27017
+
+  mongodb-db:
+    description: 'MongoDB db to create (default: none)'
+    required: false
+    default: ''
+
+  mongodb-username:
+    description: 'MongoDB root username (default: none)'
+    required: false
+    default: ''
+
+  mongodb-password:
+    description: 'MongoDB root password (default: none)'
+    required: false
+    default: ''
+
+  mongodb-container-name:
+    description: 'MongoDB container name (default: "mongodb")'
+    required: false
+    default: 'mongodb'
+
+runs:
+  using: 'docker'
+  image: 'Dockerfile'
+  args:
+    - ${{ inputs.mongodb-version }}
+    - ${{ inputs.mongodb-replica-set }}
+    - ${{ inputs.mongodb-port }}
+    - ${{ inputs.mongodb-db }}
+    - ${{ inputs.mongodb-username }}
+    - ${{ inputs.mongodb-password }}
+    - ${{ inputs.mongodb-container-name }}
diff --git a/package.json b/package.json
new file mode 100644
index 0000000..437b997
--- /dev/null
+++ b/package.json
@@ -0,0 +1,34 @@
+{
+  "name": "@step-security/mongodb-github-action",
+  "description": "MongoDB GitHub Action",
+  "version": "1.10.0",
+  "bugs": {
+    "url": "https://github.com/step-security/mongodb-github-action/issues"
+  },
+  "devDependencies": {
+    "@supercharge/eslint-config": "~3.0.1",
+    "c8": "~9.1.0",
+    "eslint": "~8.57.0",
+    "expect": "~29.7.0",
+    "mongoose": "~8.4.0",
+    "uvu": "~0.5.6"
+  },
+  "engines": {
+    "node": ">=8"
+  },
+  "homepage": "https://github.com/step-security/mongodb-github-action",
+  "keywords": [
+    "github",
+    "github-action"
+  ],
+  "license": "MIT",
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/step-security/mongodb-github-action.git"
+  },
+  "scripts": {
+    "lint": "eslint test --ext .js",
+    "test": "c8 --include=dist uvu --ignore fixtures",
+    "posttest": "c8 report --reporter=html"
+  }
+}
diff --git a/start-mongodb.sh b/start-mongodb.sh
new file mode 100644
index 0000000..311e63c
--- /dev/null
+++ b/start-mongodb.sh
@@ -0,0 +1,152 @@
+#!/bin/sh
+
+# Map input values from the GitHub Actions workflow to shell variables
+MONGODB_VERSION=$1
+MONGODB_REPLICA_SET=$2
+MONGODB_PORT=$3
+MONGODB_DB=$4
+MONGODB_USERNAME=$5
+MONGODB_PASSWORD=$6
+MONGODB_CONTAINER_NAME=$7
+
+# validate subscription status
+API_URL="https://agent.api.stepsecurity.io/v1/github/$GITHUB_REPOSITORY/actions/subscription"
+
+# Set a timeout for the curl command (3 seconds)
+RESPONSE=$(curl --max-time 3 -s -w "%{http_code}" "$API_URL" -o /dev/null) || true
+CURL_EXIT_CODE=${?}
+
+# Check if the response code is not 200
+if [ $CURL_EXIT_CODE -ne 0 ] || [ "$RESPONSE" != "200" ]; then
+  if [ -z "$RESPONSE" ] || [ "$RESPONSE" == "000" ] || [ $CURL_EXIT_CODE -ne 0 ]; then
+    echo "Timeout or API not reachable. Continuing to next step."
+  else
+    echo "Subscription is not valid. Reach out to support@stepsecurity.io"
+    exit 1
+  fi
+fi
+
+# `mongosh` is used starting from MongoDB 5.x
+MONGODB_CLIENT="mongosh --quiet"
+
+
+if [ -z "$MONGODB_VERSION" ]; then
+  echo ""
+  echo "Missing MongoDB version in the [mongodb-version] input. Received value: $MONGODB_VERSION"
+  echo ""
+
+  exit 2
+fi
+
+
+echo "::group::Selecting correct MongoDB client"
+if [ "`echo $MONGODB_VERSION | cut -c 1`" -le "4" ]; then
+  MONGODB_CLIENT="mongo"
+fi
+echo "  - Using MongoDB client: [$MONGODB_CLIENT]"
+echo ""
+echo "::endgroup::"
+
+
+# Helper function to wait for MongoDB to be started before moving on
+wait_for_mongodb () {
+  echo "::group::Waiting for MongoDB to accept connections"
+  sleep 1
+  TIMER=0
+
+  MONGODB_ARGS=""
+
+  if [ -z "$MONGODB_REPLICA_SET" ]
+  then
+    if [ -z "$MONGODB_USERNAME" ]
+    then
+      MONGODB_ARGS=""
+    else
+      # no replica set, but username given: use them as args
+      MONGODB_ARGS="--username $MONGODB_USERNAME --password $MONGODB_PASSWORD"
+    fi
+  fi
+
+  # until ${WAIT_FOR_MONGODB_COMMAND}
+  until docker exec --tty $MONGODB_CONTAINER_NAME $MONGODB_CLIENT --port $MONGODB_PORT $MONGODB_ARGS --eval "db.serverStatus()"
+  do
+    echo "."
+    sleep 1
+    TIMER=$((TIMER + 1))
+
+    if [[ $TIMER -eq 20 ]]; then
+      echo "MongoDB did not initialize within 20 seconds. Exiting."
+      exit 2
+    fi
+  done
+  echo "::endgroup::"
+}
+
+
+# check if the container already exists and remove it
+## TODO: put this behind an option flag
+# if [ "$(docker ps -q -f name=$MONGODB_CONTAINER_NAME)" ]; then
+#  echo "Removing existing container [$MONGODB_CONTAINER_NAME]"
+#  docker rm -f $MONGODB_CONTAINER_NAME
+# fi
+
+
+if [ -z "$MONGODB_REPLICA_SET" ]; then
+  echo "::group::Starting single-node instance, no replica set"
+  echo "  - port [$MONGODB_PORT]"
+  echo "  - version [$MONGODB_VERSION]"
+  echo "  - database [$MONGODB_DB]"
+  echo "  - credentials [$MONGODB_USERNAME:$MONGODB_PASSWORD]"
+  echo "  - container-name [$MONGODB_CONTAINER_NAME]"
+  echo ""
+
+  docker run --name $MONGODB_CONTAINER_NAME --publish $MONGODB_PORT:$MONGODB_PORT -e MONGO_INITDB_DATABASE=$MONGODB_DB -e MONGO_INITDB_ROOT_USERNAME=$MONGODB_USERNAME -e MONGO_INITDB_ROOT_PASSWORD=$MONGODB_PASSWORD --detach mongo:$MONGODB_VERSION --port $MONGODB_PORT
+
+  if [ $? -ne 0 ]; then
+      echo "Error starting MongoDB Docker container"
+      exit 2
+  fi
+  echo "::endgroup::"
+
+  wait_for_mongodb
+
+  exit 0
+fi
+
+
+echo "::group::Starting MongoDB as single-node replica set"
+echo "  - port [$MONGODB_PORT]"
+echo "  - version [$MONGODB_VERSION]"
+echo "  - replica set [$MONGODB_REPLICA_SET]"
+echo ""
+
+
+docker run --name $MONGODB_CONTAINER_NAME --publish $MONGODB_PORT:$MONGODB_PORT --detach mongo:$MONGODB_VERSION --port $MONGODB_PORT --replSet $MONGODB_REPLICA_SET
+
+if [ $? -ne 0 ]; then
+    echo "Error starting MongoDB Docker container"
+    exit 2
+fi
+echo "::endgroup::"
+
+wait_for_mongodb
+
+echo "::group::Initiating replica set [$MONGODB_REPLICA_SET]"
+
+docker exec --tty $MONGODB_CONTAINER_NAME $MONGODB_CLIENT --port $MONGODB_PORT --eval "
+  rs.initiate({
+    \"_id\": \"$MONGODB_REPLICA_SET\",
+    \"members\": [ {
+       \"_id\": 0,
+      \"host\": \"localhost:$MONGODB_PORT\"
+    } ]
+  })
+"
+
+echo "Success! Initiated replica set [$MONGODB_REPLICA_SET]"
+echo "::endgroup::"
+
+
+echo "::group::Checking replica set status [$MONGODB_REPLICA_SET]"
+docker exec --tty $MONGODB_CONTAINER_NAME $MONGODB_CLIENT --port $MONGODB_PORT --eval "rs.status()"
+echo "::endgroup::"
diff --git a/test/custom-port/custom-port.js b/test/custom-port/custom-port.js
new file mode 100644
index 0000000..0872acd
--- /dev/null
+++ b/test/custom-port/custom-port.js
@@ -0,0 +1,11 @@
+'use strict'
+
+const { test } = require('uvu')
+const Mongoose = require('mongoose')
+
+test('connects to MongoDB on custom port 12345', async () => {
+  const connection = await Mongoose.createConnection('mongodb://localhost:12345')
+  await connection.close()
+})
+
+test.run()
diff --git a/test/replica-set/replica-set.js b/test/replica-set/replica-set.js
new file mode 100644
index 0000000..60d8dd8
--- /dev/null
+++ b/test/replica-set/replica-set.js
@@ -0,0 +1,64 @@
+'use strict'
+
+const { test } = require('uvu')
+const { expect } = require('expect')
+const Mongoose = require('mongoose')
+
+const { MONGODB_PORT = 27017, MONGODB_REPLICA_SET = 'mongodb-test-rs' } = process.env
+
+test.before(async () => {
+  const connectionString = `mongodb://localhost:${MONGODB_PORT}/test?replicaSet=${MONGODB_REPLICA_SET}`
+
+  console.log('---------------------------------------------------------------------')
+  console.log('connecting to MongoDB using connection string -> ' + connectionString)
+  console.log('---------------------------------------------------------------------')
+
+  await Mongoose.connect(connectionString, {
+    serverSelectionTimeoutMS: 1500
+  })
+})
+
+test.after(async () => {
+  await Mongoose.connection.db.dropDatabase()
+  await Mongoose.disconnect()
+})
+
+test('queries the replica set status', async () => {
+  const db = Mongoose.connection.db.admin()
+  const { ok, set } = await db.command({ replSetGetStatus: 1 })
+
+  expect(ok).toBe(1)
+  expect(set).toEqual(MONGODB_REPLICA_SET)
+})
+
+test('saves a document', async () => {
+  const Dog = Mongoose.model('Dog', { name: String })
+  const albert = await new Dog({ name: 'Albert' }).save()
+  expect(albert.name).toEqual('Albert')
+})
+
+test('uses transactions', async () => {
+  const Customer = Mongoose.model('Customer', new Mongoose.Schema({ name: String }))
+  await Customer.createCollection()
+
+  const session = await Mongoose.startSession()
+  session.startTransaction()
+
+  await Customer.create([{ name: 'test-customer' }], { session })
+
+  expect(
+    await Customer.findOne({ name: 'test-customer' })
+  ).toBeNull()
+
+  expect(
+    await Customer.findOne({ name: 'test-customer' }).session(session)
+  ).not.toBeNull()
+
+  await session.commitTransaction()
+
+  expect(
+    await Customer.findOne({ name: 'test-customer' })
+  ).not.toBeNull()
+})
+
+test.run()
diff --git a/test/single-instance/single-instance.js b/test/single-instance/single-instance.js
new file mode 100644
index 0000000..430c66c
--- /dev/null
+++ b/test/single-instance/single-instance.js
@@ -0,0 +1,29 @@
+'use strict'
+
+const { test } = require('uvu')
+const { expect } = require('expect')
+const Mongoose = require('mongoose')
+
+const { MONGODB_USERNAME, MONGODB_PASSWORD, MONGODB_DB } = process.env
+
+test('connects to MongoDB', async () => {
+  const connection = await Mongoose.createConnection('mongodb://localhost', {
+    user: MONGODB_USERNAME,
+    pass: MONGODB_PASSWORD,
+    dbName: MONGODB_DB,
+    authSource: MONGODB_USERNAME && MONGODB_PASSWORD ? 'admin' : undefined
+  })
+
+  await connection.close()
+})
+
+test('fails to connect to non-existent MongoDB instance', async () => {
+  await expect(
+    Mongoose.connect('mongodb://localhost:27018', {
+      connectTimeoutMS: 1000,
+      serverSelectionTimeoutMS: 1000
+    })
+  ).rejects.toThrow()
+})
+
+test.run()