# Holosources

Holosources are named remote Git branches that content can be pulled from during projection. They can refer to any ref or hash in a remote repository, and optionally a holobranch within that.

## Overriding via environment

Holosources can be overridden via `HOLO_SOURCE_*` environment variables.

### Variable names

For example, a source named `parent-blueprint` could be overridden via `HOLO_SOURCE_PARENT_BLUEPRINT`. The transformation from source name to environment variable name is applied as follows:

- Hyphens (`-`) replaced with underscores (`_`)
- All letters capitalized

### Change URL

You can change just the URL, preserving declared ref+holobranch:

```bash
HOLO_SOURCE_PARENT_BLUEPRINT="https://github.com/myorg/myfork"
```

Local paths work too:

```bash
HOLO_SOURCE_PARENT_BLUEPRINT="/src/myfork"
```

### Change ref

You can change just the ref, preserving declared url+holobranch:

```bash
HOLO_SOURCE_PARENT_BLUEPRINT="#refs/heads/develop"
```

### Change holobranch

You can change just the holobranch, preserving declared url+ref:

```bash
HOLO_SOURCE_PARENT_BLUEPRINT="=>helm-chart"
```

### Change everything

You can reconfigure an entire source:

```bash
HOLO_SOURCE_PARENT_BLUEPRINT="/src/myfork#refs/heads/develop=>helm-chart"
```

Or clear out a declared holobranch component to use a native ref directly:

```bash
HOLO_SOURCE_PARENT_BLUEPRINT="/src/myfork#refs/heads/develop=>"
```