Smaller (in code; memory is up for debate) and more configurable guest agent for Openstack
- xen-tools if using xen
- python-daemon
- pycrypto
Provides an alternative to openstack-guest-agents-unix that tries to accomplish the following as well as provide as much functionality of the aforementioned as well:
- Small *nix style daemon without any other considerations
- Pluggable functionality for the configurations managed
- Modular design in the hypervisor communication mechanisms
- More configurable (ability to restrict managed items by singularity)
There are features that openstack-guest-agents-unix provides directly that we delegate to other softwares to accomplish:
- Locked to a particular python environment -> handled by virtualenv
Provides two subcommands (apply and daemon). The daemon command controls the daemonization of the service and once started resspond to a few signals (explained below). The apply subcommand on the other hand takes cached items and re-applies them to the live system. See the help for singularity (and its subcommands) for more information and options.
Nearly all options on the command line can be set in the appropriate section of the configuration file (defaults to /etc/singularity/singularity.conf)
- SIGHUP -> daemon reload
- SIGTERM,SIGINT -> daemon stop
The following is an example exchange between the hypervisor and guest for a working openstack guest agent (the hypervisor is designated H and the guest, G):
H: {"name":"version", "value":"agent"}
G: {"message":"9999", "returncode":"0"}
H: {"name":"features", "value":""}
G: {"message":"resetnetwork,injectfile,version,password,features,keyinit", "returncode":"0"}
H: {"name":"resetnetwork", "value":""}
G: {"message":"", "returncode":"0"}
H: {"name":"keyinit", "value":"126190143978468524724357084322869"}
G: {"message":"152515189133785336521547047713056", "returncode":"D0"}
H: {"name":"password", "value":"YXazuqvtFdagFYrwKoYhWAbaJoW9eB7f+ju7GSwhBh4="}
G: {"message":"", "returncode":"0"}