image-unpacker

The ImageUnpacker daemon can be used to unpack imageserver images into partitions or external volumes.

The image-unpacker daemon is used by the AMI Publisher to unpack images onto external volumes that can then be used to create AMIs. See the design document for more information.

Status page

The image-unpacker provides a web interface on port 6974 which shows a status page, links to built-in dashboards and access to performance metrics and logs. If image-unpacker is running on host myhost then the URL of the main status page is http://myhost:6974/. An RPC over HTTP interface is also provided over the same port.

Startup

image-unpacker is started at boot time, usually by one of the provided init scripts. The image-unpacker process is baby-sat by the init script; if the process dies the init script will re-start it. It may be stopped with the command:

service image-unpacker stop

which also kills the baby-sitting init script. It may be started with the command:

service image-unpacker start

There are many command-line flags which may change the behaviour of image-unpacker but many have defaults which should be adequate for most deployments. Built-in help is available with the command:

image-unpacker -h

Security

RPC access is restricted using TLS client authentication. image-unpacker expects a root certificate in the file /etc/ssl/CA.pem which it trusts to sign certificates which grant access to methods. It trusts the root certificate in the /etc/ssl/IdentityCA.pem file to sign identity-only certificates.

It also requires a certificate and key which grant it the ability to fetch images and objects from an imageserver. These should be in the files /etc/ssl/image-unpacker/cert.pem and /etc/ssl/image-unpacker/key.pem, respectively.

Control

The unpacker-tool utility may be used to manage the service. Normally the AMI Publisher is used for higher-level image publication and management.