You often have sensitive data like usernames, passwords, keys, ... that are used
throughout projects, and that you don't want to commit with your codebase.
Other data like global or machine-specific configuration values are also better
stored outside your project.

## Bld property hierarchy

`bld` provides access to RIFE2's [hierarchical properties](https://github.com/rife2/rife2/wiki/Hierarchical-Properties)
infrastructure and allows you to put this sensitive data anywhere in the hierarchy
that makes sense to you.

Since `bld` doesn't execute in a web environment, the property collection
hierarchy is different:

```
   Project Properties
           ↓
Java System Properties
           ↓
[Local Properties File] 
           ↓
 [Bld Properties File] 
           ↓
[Custom Properties File] 
           ↓
  System Env Variables
```

* `[Local Properties File]` is an optional properties file named `local.properties`
that `bld` will search for in the top-level directory of your project.
  

* `[Bld Properties File]` is another optional properties file name
`bld.properties` that `bld` will search for in your home directory at
`$HOME/.bld/bld.properties`
  

* `[Custom Properties File]` is a third optional properties file that will
be looked for at the location set in the `RIFE2_PROPERTIES_FILE` environment
variable.

## Use properties in your project

Once you have set up the properties in any of the locations in the hierarchy,
you can easily access them in your project.

For example:

```java
public class MyAppBuild extends WebProject {
    public MyAppBuild() {
        // ...
        publishOperation()
            .repository(
                repository("https://repo.rife2.com/releases",
                    property("rife2.username"),
                    property("rife2.password")))
            .info()
            .signKey(property("sign.key"))
            .signPassphrase(property("sign.passphrase"));
        // ...
    }
    // public static void main ...
}
```

Now, imagine that you have set up `rife2.username` and `rife2.password` in
`$HOME/.bld/bld.properties`, but that you temporarily want to use different
values, then you can for instance use Java system properties to override them:

```console
./bld -Drife2.username=other_user -Drife2.password=other_pass clean publish
```

RIFE2's hierarchical properties are a really powerful and convenient way
to externalize data.

---

*Next learn more about [Upgrading](Upgrading)*