[2024-feb-29] Sad news: Eric Layton aka Nocturnal Slacker aka vtel57 passed away on Feb 26th, shortly after hospitalization. He was one of our Wiki's most prominent admins. He will be missed.
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howtos:emulators:helper_script_for_managing_qemu_virtual_machines [2016/09/01 09:17 (UTC)] – [Using Qemu from Unprivileged Users] louigi600 | howtos:emulators:helper_script_for_managing_qemu_virtual_machines [2022/06/08 10:48 (UTC)] – [Sources] zeebra | ||
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====== Preface ====== | ====== Preface ====== | ||
- | Qemu is a popular and powerful open-source emulator often used for running KVM virtual machines. In fact qemu supports emulating so many thins that it can be quite challenging, | + | Qemu is a popular and powerful open-source emulator often used for running KVM Virtual Machines (VMs). In fact qemu supports emulating so many things |
qemu-system-arm -name armedslack -M versatilepb -m 256 -k en-us -vnc :5,password -usb -kernel / | qemu-system-arm -name armedslack -M versatilepb -m 256 -k en-us -vnc :5,password -usb -kernel / | ||
- | Ok everyone might want console redirect on vnc and monitor redirect via telnet but non the less that's still a relatively small subset of the options supported by qemu-system-arm and only has one disk one cdrom and one Network Interface Controller (NIC) so things can be much worse then this. | + | Not everyone might want console redirect on vnc and monitor redirect via telnet but non the less that's still a relatively small subset of the options supported by qemu-system-arm and only has one disk one cdrom and one Network Interface Controller (NIC) so things can be much worse then this. |
- | Is is common | + | Is is common, for people running qemu VMs, to use some sort of software |
- | Over the years I've radically changed the helper script form having text configuration files for each VM to a centarl VM configuration database. I'd like to share my experience in doing so without presumptuously declaring that I do this any better then anyone else, letting you decide what's good or bad for your needs. It's likely that someone else has done this and a lot better then me but nevertheless I's still like to hare with you the route I took. | + | Over the years I've radically changed the helper script form having text configuration files for each VM to a centarl VM configuration database. I'd like to share my experience in doing so without presumptuously declaring that I do this any better then anyone else, letting you decide what's good or bad for your needs. It's likely that someone else has done this and a lot better then me but nevertheless I'd still like to hare with you the route I took. |
====== Problems ====== | ====== Problems ====== | ||
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* ability to run both x86 and ARM virtual machines | * ability to run both x86 and ARM virtual machines | ||
* ability to run several VMs simultaneously | * ability to run several VMs simultaneously | ||
+ | * have the VMs appear as a real server in the LAN | ||
* flexibility on the number of disks assigned to a VM | * flexibility on the number of disks assigned to a VM | ||
* flexibility on the number of NICs assigned to a VM | * flexibility on the number of NICs assigned to a VM | ||
- | * avoid conflicts on tap and MAC address | ||
* avoid conflicts on VM console vnc port | * avoid conflicts on VM console vnc port | ||
* avoid conflicts on VM monitor port | * avoid conflicts on VM monitor port | ||
- | Dealing with such issues on a text based configuration file per each VM started making the code unnecessarily complicated. | ||
- | Manually creating a configuration file for a new VM required looking for information across all previously configured VMs configuration files. | ||
- | Another problem that you may come across while running VMs in general is networking | + | Wanting |
+ | |||
+ | Using the initial, per VM text based configuration, | ||
====== Proposed Solution ====== | ====== Proposed Solution ====== | ||
- | It quickly became apparent to me that the VM configuration would need to be generated rather then manually created and that a central configuration repository would much aid the process. Again a text based central configuration file would make the code in inherently complicated (having to deal with an arbitrary number of VMs each with arbitrary number of disks and NICs). | + | It quickly became apparent to me that the VM configuration would need to be generated rather then manually created and that a central configuration repository would much aid the process. Again a text based central configuration file would make, either |
- | Having some experience on database administration made it a little unappealing to use LDAP for central repository and even if I had no DB experience at all I doubt I'd actually want the overhead of running LDAP just for this. Running MariaDB or Postgres | + | Having some experience on database administration made it a little unappealing to use LDAP for central repository and even if I had no DB experience at all I doubt I'd actually want the overhead of running LDAP just for this. Running MariaDB or Postgres was equally |
+ | |||
+ | |||
+ | Another thing that quickly became apparent was the almost repetitive code required to prompt for all the options so I decided to address that in 2 ways: | ||
+ | - have as much of the promoting automatically generated with a clever workaround | ||
+ | - use dialog to further simplify the UI for prompting | ||
- | Another thing quickly became apparent was that a lot of code was required to prompt for all the options on the text console. I find that dialog can be really handy for this along with making a better appealing interface. | ||
===== Basic Configuration ===== | ===== Basic Configuration ===== | ||
- | To get better flexibility | + | To get better flexibility |
* Path to folder that will contain all the VMs | * Path to folder that will contain all the VMs | ||
* Path to where the centralized VM configuration DB is | * Path to where the centralized VM configuration DB is | ||
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QEMUERS ALL=(ALL) NOPASSWD: QEMU | QEMUERS ALL=(ALL) NOPASSWD: QEMU | ||
- | This would be sufficient to run the VMs as any of the unprivileged users in QEMUERS user alias (al, john, jack) but the management script would need to run sudo qemu-system-* .... | + | This would be sufficient to run the VMs as any of the unprivileged users in QEMUERS user alias (al, john, jack) but the management script would need to run sudo qemu-system-* .... this is easy to obtain: |
+ | |||
+ | [ $(/ | ||
+ | eval $(echo "$CMD &" | ||
+ | |||
+ | Alternatively you could give privileges to execute the management script as root. | ||
===== Examples ===== | ===== Examples ===== | ||
Here are examples of the dialogs that user would see wile creating, starting, stopping and deleting a VM. | Here are examples of the dialogs that user would see wile creating, starting, stopping and deleting a VM. | ||
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====== Sources ====== | ====== Sources ====== | ||
+ | I've a blog entry on LQ where I talk a little more extensively on minimizing the code in bash scripts. | ||
+ | [[http:// | ||
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