cosmium/README.md

# Cosmium

Cosmium is a lightweight Cosmos DB emulator designed to facilitate local development and testing. While it aims to provide developers with a solution for running a local database during development, it's important to note that it's not 100% compatible with Cosmos DB. However, it serves as a convenient tool for E2E or integration tests during the CI/CD pipeline. Read more about compatibility [here](./docs/COMPATIBILITY.md).

One of Cosmium's notable features is its ability to save and load state to a single JSON file. This feature makes it easy to load different test cases or share state with other developers, enhancing collaboration and efficiency in development workflows.

# Getting Started

### Installation via Homebrew

You can install Cosmium using Homebrew by adding the `pikami/brew` tap and then installing the package.

```sh
brew tap pikami/brew
brew install cosmium
```

This will download and install Cosmium on your system, making it easy to manage and update using Homebrew.

### Downloading Cosmium Binaries

You can download the latest version of Cosmium from the [GitHub Releases page](https://github.com/pikami/cosmium/releases). Choose the appropriate release for your operating system and architecture.

### Supported Platforms

Cosmium is available for the following platforms:

- **Linux**: cosmium-linux-amd64
- **macOS**: cosmium-darwin-amd64
- **macOS on Apple Silicon**: cosmium-darwin-arm64
- **Windows**: cosmium-windows-amd64.exe

### Running Cosmium

Once downloaded, you can launch Cosmium using the following command:

```sh
cosmium -Persist "./save.json"
```

Connection String Example:

```
AccountEndpoint=https://localhost:8081/;AccountKey=C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==;
```

### Running Cosmos DB Explorer

If you want to run Cosmos DB Explorer alongside Cosmium, you'll need to build it yourself and point the `-ExplorerDir` argument to the dist directory. Please refer to the [Cosmos DB Explorer repository](https://github.com/Azure/cosmos-explorer) for instructions on building the application.

Once running, the explorer can be reached by navigating following URL: `https://127.0.0.1:8081/_explorer/` (might be different depending on your configuration).

### Running with docker (optional)

If you wan to run the application using docker, configure it using environment variables see example:

```sh
docker run --rm \
  -e COSMIUM_PERSIST=/save.json \
  -v ./save.json:/save.json \
  -p 8081:8081 \
  ghcr.io/pikami/cosmium
```

### SSL Certificate

By default, Cosmium uses a pre-generated SSL certificate. You can provide your own certificates by specifying paths to the SSL certificate and key (PEM format) using the `-Cert` and `-CertKey` arguments, respectively.

To disable SSL and run Cosmium on HTTP instead, you can use the `-DisableTls` flag. However most applications will require HTTPS.

### Other Available Arguments

- **-AccountKey**: Account key for authentication (default "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==")
- **-DisableAuth**: Disable authentication
- **-Host**: Hostname (default "localhost")
- **-InitialData**: Path to JSON containing initial state
- **-Persist**: Saves data to the given path on application exit (When `-InitialData` argument is not supplied, it will try to load data from path supplied in `-Persist`)
- **-Port**: Listen port (default 8081)
- **-Debug**: Runs application in debug mode, this provides additional logging

These arguments allow you to configure various aspects of Cosmium's behavior according to your requirements.

All mentioned arguments can also be set using environment variables:

- **COSMIUM_ACCOUNTKEY** for `-AccountKey`
- **COSMIUM_DISABLEAUTH** for `-DisableAuth`
- **COSMIUM_HOST** for `-Host`
- **COSMIUM_INITIALDATA** for `-InitialData`
- **COSMIUM_PERSIST** for `-Persist`
- **COSMIUM_PORT** for `-Port`
- **COSMIUM_DEBUG** for `-Debug`

# License

This project is [MIT licensed](./LICENSE).