emu-cli: a small control toolkit for qemu

emu-cli installs the emu tool, which is a CLI program currently aimed at making x86 VM usage easier for Linux desktop users.

It contains commands to:

• Manage VMs as a system-wide fleet
  • List all VMs in one place
  • Clone and Import VMs from other sources
• Create, Delete, Start and Stop VMs
  • ISOs can be attached
  • You can start VMs with or without graphical screens
  • emu does not have to be running to maintain your VM
• Supervise VMs with systemd
  • Uses the user profile (systemctl --user)
  • Knows about which systemd units its maintaining
    • Deletes them when the VM is deleted
• Manage settings for VMs
  • RAM, CPUs, Video & CPU type
  • Forward Ports to VM networks
• Define a SSH port that stays with the VM and emu ssh to it easily
• Poke and prod at your VMs with emu nc, which opens a TCP socket to the port on the VM
• Play with qemu QMP commands to control your VM externally

Requirements

Linux with systemd and qemu. It places things according to the XDG standards, so that means $HOME/.local will have the VMs, etc.

To build the software, you will need a working rust environment. I strongly recommend rustup.

Stability

emu is still undergoing some UI changes. I do use it somewhat regularly, but there may be additional work that needs to be done for a larger goal that changes small things as they stand now. I don't foresee any need to do needless changes, however.

emu has bugs, particularly nasty ones at times related to your VMs. I would not use emu in a setting where data integrity mattered much.

Installation

cargo install emu-cli

Once installed, you can invoke the software with emu.

Usage

$ emu create myvm 50 # gigabytes of storage
# start the vm with the cdrom set to the ubuntu iso. Press ^C to terminate the vm.
$ emu run myvm --cdrom ubuntu.iso

# make a copy before doing something dumb
$ emu clone myvm myvm.template
$ emu list
myvm
myvm.template

# supervision in systemd

$ emu supervise myvm
$ emu supervised
myvm (6 GB)
$ systemctl --user start myvm.emu # or enable it, if you'd like. it sticks to your login session.
$ systemctl --user stop myvm.emu # graceful shutdown
$ emu unsupervise myvm
# ssh support
$ emu config port map myvm 2222 22
$ emu config port map myvm 8000 80
$ emu config set myvm ssh-port 2222
# run detached and without a screen
$ emu run --detach --headless myvm
$ emu ssh myvm
myvm$ exit
$ emu nc myvm 8000
GET / HTTP/1.1
Host: localhost
HTTP/1.1 403 Forbidden
Connection: close
# cleanup
$ emu shutdown myvm
$ emu remove myvm
$ emu list
myvm.template (6 GB)

Configuration

Configuration is provided currently by injecting values into a file under ~/.local/share/emu/<VM>/config. It is in TOML format. Values are not completed documented yet.

[machine]
cpus = 4 # actually cores
memory = 512 # megabytes

[ports]
2222 = 22 # host -> guest map

You can control these values with emu config <subcommand> sub-commands.

$ emu config show myvm
[machine]
cpus = 4
memory = 512

[ports]
2222 = 22

$ emu config port map myvm 2223 23
$ emu config port unmap myvm 2223

$ emu config set myvm cpus 8

License

MIT

Author

Erik Hollensbe github@hollensbe.org