from an existing OUTSCALE VM by mounting the root device and using a
[Chroot](https://en.wikipedia.org/wiki/Chroot) environment to provision
that device. This is an **advanced builder and should not be used by
newcomers**. However, it is also the fastest way to build an EBS-backed OMI
since no new OUTSCALE VM needs to be launched.
- [osc-bsusurrogate](/docs/builders/osc-bsusurrogate.html) - Create BSU-backed OMIs from scratch. Works similarly to the `chroot` builder but does
not require running in Outscale VM. This is an **advanced builder and should not be
used by newcomers**.
->**Don't know which builder to use?** If in doubt, use the [osc-bsu
builder](/docs/builders/osc-bsu.html). It is much easier to use and Outscale generally recommends BSU-backed images nowadays.
# Outscale BSU Volume Builder
Packer is able to create Outscale BSU Volumes which are preinitialized with a filesystem and data.
- [osc-bsuvolume](/docs/builders/osc-bsuvolume.html) - Create EBS volumes by launching a source OMI with block devices mapped. Provision the VM, then destroy it, retaining the EBS volumes.
## Authentication
The OUTSCALE provider offers a flexible means of providing credentials for authentication. The following methods are supported, in this order, and explained below:
- Static credentials
- Environment variables
- Shared credentials file
- Outscale Role
### Static Credentials
Static credentials can be provided in the form of an access key id and secret.