The Hydra Python project and the [[Hydra for NixOS]] are not related; they serve different purposes and are part of distinct ecosystems.
1. **Hydra Python Project**: This is a framework developed by Facebook Research, designed for elegantly configuring complex applications. The Python Hydra project allows developers to manage configurations through a hierarchical structure, using YAML files, and makes it easy to switch between different configurations. It's widely used in Python applications for machine learning, research, and other fields where flexible configuration management is crucial.
2. **Hydra on NixOS**: This is a continuous integration server, built specifically for the Nix package manager. Hydra on NixOS is used to automatically build and test software projects, particularly those managed with Nix expressions. It supports building on multiple platforms and can manage complex software dependencies using the NixOS's declarative approach.
These two projects share a name but are targeted towards different aspects of software development and deployment.
# Usage
Here's how to install [[Hydra for Python]] along with some additional explanations:
**Installation**
The core Hydra package is installed using pip:
Bash
```
pip install hydra-core --upgrade
```
**Explanation**
- **hydra-core:** This is the core Hydra package that provides the essential functionality for configuring complex applications in Python.
- **--upgrade:** This flag ensures you have the latest version of Hydra. It's recommended to use this to get the most up-to-date features and bug fixes.
**Getting Started**
Here's a quick example to see how Hydra works:
1. **Create a YAML configuration file (e.g., "conf/config.yaml"):**
Note that the file is located in the **"conf"** directory.
```
db:
driver: mysql
user: my_username
password: secret_password
```
1. **Create a Python script (e.g., my_app.py):**
Note the **@hydra.main()** decorator points **config_path** to "conf"
```python
from omegaconf import DictConfig, OmegaConf
import hydra
@hydra.main(version_base=None, config_path="conf", config_name="config")
def my_app(cfg: DictConfig) -> None:
print(OmegaConf.to_yaml(cfg))
if __name__ == "__main__":
my_app()
```
3. **Run your script:**
Bash
```
python my_app.py
```
**Key Concepts**
- **Configuration files:** Hydra lets you structure configuration parameters in a clear, hierarchical manner using YAML or other supported formats.
- **@hydra.main decorator:** This decorator is the entry point for your Hydra application. It automatically handles loading the configuration.
- **Composition:** Hydra lets you compose configurations from multiple files and override them easily from the command line, making your applications highly flexible.
**Where to learn more:**
- **Hydra Documentation:** [https://hydra.cc/docs/intro/](https://hydra.cc/docs/intro/)
- **Hydra's Compose API:** This is a useful alternative if you want fine-grained programmatic control over your configurations.
# References
```dataview
Table title as Title, authors as Authors
where contains(subject, "Hydra") or contains(subject, "Configuration Management")
sort title, authors, modified, desc
```