Remote bootstrapping

bootstrap-vz is able to bootstrap images not only on the machine on which it is invoked, but also on remote machines that have bootstrap-vz installed.

This is helpful when you create manifests on your own workstation, but have a beefed up remote build server which can create images quickly. There may also be situations where you want to build multiple manifests that have different providers and require the host machines to be running on that provider (e.g. EBS backed AMIs can only be created on EC2 instances), when doing this multiple times SSHing into the machines and copying the manifests can be a hassle.

Lastly, the main motivation for supporting remote bootstrapping is the automation of integration testing. As you will see further down, bootstrap-vz is able to select which build server is required for a specific test and run the bootstrapping procedure on said server.


Normally you’d use bootstrap-vz to start a bootstrapping process. When bootstrapping remotely simply use bootstrap-vz-remote instead, it takes the same arguments plus a few additional ones:

  • --servers <path>: Path to a list of build-servers (see build-servers.yml for more info)
  • --name <name>: Selects a specific build-server from the list of build-servers
  • --release <release>: Restricts the autoselection of build-servers to the ones with the specified release

Much like when bootstrapping directly, you can press Ctrl+C at any time to abort the bootstrapping process. The remote process will receive the keyboard interrupt signal and begin cleaning up - pressing Ctrl+C a second time will abort that as well and kill the connection immediately.

Note that there is also a bootstrap-vz-server, this file is not meant to be invoked directly by the user, but is instead launched by bootstrap-vz on the remote server when connecting to it.


For the remote bootstrapping procedure to work, you will need to install bootstrap-vz as well as the sudo command on the remote machine. Also make sure that all the needed dependencies for bootstrapping your image are installed.

Locally the pip package Pyro4 is needed.


The file build-servers.yml informs bootstrap-vz about the different build servers you have at your disposal. In its simplest form you can just add your own machine like this:

  type: local
  can_bootstrap: [virtualbox]
  release: jessie
  build_settings: {}

type specifies how bootstrap-vz should connect to the build-server. local simply means that it will call the bootstrapping procedure directly, no new process is spawned.

can_bootstrap tells bootstrap-vz for which providers this machine is capable of building images. With the exception of the EC2 provider, the accepted values match the accepted provider names in the manifest. For EC2 you can specify ec2-s3 and/or ec2-ebs. ec2-ebs specifies that the machine in question can bootstrap EBS backed images and should only be used when the it is located on EC2. ec2-s3 signifies that the machine is capable of bootstrapping S3 backed images.

Beyond being a string, the value of release is not enforced in any way. It’s only current use is for bootstrap-vz-remote where you can restrict which build-server should be autoselected.

Remote settings

The other (and more interesting) setting for type is ssh, which requires a few more configuration settings:

  type: ssh
    - virtualbox
    - ec2-s3
  release: wheezy
  # remote settings below here
  port: 2222
  username: admin
  keyfile: path_to_private_key_file
  server_bin: /root/bootstrap/bootstrap-vz-server

The last 5 settings specify how bootstrap-vz can connect to the remote build-server. While the initial handshake is achieved through SSH, bootstrap-vz mainly communicates with its counterpart through RPC (the communication port is automatically forwarded through an SSH tunnel). address, port, username and keyfile are hopefully self explanatory (remote machine address, SSH port, login name and path to private SSH key file).

server_bin refers to the aboved mentioned bootstrap-vz-server executable. This is the command bootstrap-vz executes on the remote machine to start the RPC server.

Be aware that there are a few limitations as to what bootstrap-vz is able to deal with, regarding the remote machine setup (in time they may be fixed by a benevolent contributor):

  • The login user must be able to execute sudo without a password
  • The private key file must be added to the ssh-agent before invocation (alternatively it may not be password protected)
  • The server must already be part of the known_hosts list (bootstrap-vz uses ssh directly and cannot handle interactive prompts)

Build settings

The build settings allow you to override specific manifest properties. This is useful when for example the VirtualBox guest additions ISO is located at /root/guest_additions.iso on server 1, while server 2 has it at /root/images/vbox.iso.

  type: local
    - virtualbox
    - ec2-s3
  release: jessie
    guest_additions: /root/images/VBoxGuestAdditions.iso
      port: 3142
      secret-key: thes3cr3tkeyf0ryourawsaccount/FS4d8Qdva
      certificate: /root/manifests/cert.pem
      private-key: /root/manifests/pk.pem
      user-id: 1234-1234-1234
    s3-region: eu-west-1
  • guest_additions specifies the path to the VirtualBox guest additions ISO on the remote machine.
  • apt_proxy sets the configuration for the apt_proxy plugin <../plugins/apt_proxy>.
  • ec2-credentials contains all the settings you know from EC2 manifests, note that when running integration tests, these credentials are also used when running instances.
  • s3-region overrides the s3 bucket region when bootstrapping S3 backed images.