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Give Your PXE Wings! It’S Not Magic! How Booting Actually Works

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Give Your PXE Wings! It’S Not Magic! How Booting Actually Works Give Your PXE Wings! It’s not magic! How booting actually works. Presentation for virtual SREcon 2020 By Rob Hirschfeld, RackN Rob Hirschfeld @zehicle Co-Founder of RackN We created Digital Rebar Bare Metal Provisioning ++ @L8istSh9y Podcast on PXE: http://bit.ly/pxewings In concept, O/SO/S Provisioning is Easy! We’re just installing an operating system on a server or switch! Why is that so hard?! ● Bootstrapping ● Firmware Limitations ● Variation ● Networking ● Security ● Performance Computer ● Post configuration In concept, Pre- & Provisioning is Easy! Post- Config We’re just installing an operating system on a server or switch! Why is that so hard?! ● Bootstrapping ● Firmware Limitations And that’s not even including: ● Variation ● Networking ● System Inventory ● Security ● System Validation ● Performance ● Hardware Configuration ● Post configuration ● Naming & Addressing ● Credentials Injection Exploring Provisioning Approaches Netboot (25 min) Image Deploy (10 min) Esoteric Flavors (5 min) ● PXE ● Packer ● kexec ● iPXE ● Write Boot Part ● Secure Boot ● ONIE ● Cloud Init ● BMC Boot ● Kickstart ● Preseed Exploring Provisioning Approaches Netboot (25 min) Image Deploy (10 min) Esoteric Flavors (5 min) ● PXE ● Packer ● kexec ● iPXE ● Write Boot Part ● Secure Boot ● ONIE ● Cloud Init ● BMC Boot ● Kickstart ● Preseed All roads lead to a kernel init process PXE PXE Let’s PXE! Bootstrapping is a multi-stage process Server DHCP Firmware PXE NextServer & Options TFTP Bootloader Stage 1 lpxelinux.0 Provisioning Service(s) HTTP(S) Bootloader Stage 2 ipxe.efi HTTP(S) O/S Kernel O/S ISO First: Get on the network Server DHCP Firmware PXE NextServer & Options Provisioning Service(s) Then: Download a Bootloader Server TFTP Bootloader Stage 1 lpxelinux.0 Provisioning Service(s) Then get a BETTER Bootloader Server Provisioning Service(s) HTTP(S) Bootloader Stage 2 ipxe.efi Finally load a “real” operating system Server Provisioning Service(s) HTTP(S) O/S Kernel O/S ISO Each stage is actually a NEW O/S Load Server DHCP Firmware DHCP PXE NextServer & Options TFTP Bootloader DHCP Stage 1 lpxelinux.0 Provisioning Service(s) HTTP(S) Bootloader Stage 2 ipxe.efi DHCP HTTP(S) DHCP O/S Kernel O/S ISO And modern servers can skip TFTP! So… technically, no longer PXE Server DHCP Firmware PXE NextServer & Options Provisioning Service(s) HTTP(S) Bootloader Stage 2 ipxe.efi HTTP(S) O/S Kernel O/S ISO Yay! We’re done, right? Provisioning is more than PXE Server iPXE O/S Kernel Bootloader O/S ISO Config Kickstart Templates Provisioning Service(s) Download Installation Packages Access & Post-Config Apps Hardware varies, so Install must be guided by templates Server O/S Kernel Config Kickstart Templates Provisioning Service(s) ISOs are minimal and stale So they must be updated Server O/S Kernel Kickstart Provisioning Service(s) Download Repo Installation Packages Mirrors And then you can actually connect to start configuring the system! Server O/S Kernel Kickstart Provisioning Service(s) Installation Access & Post-Config Apps Automating Provisioning means Connecting all these steps together Server iPXE O/S Kernel Bootloader O/S ISO Config Kickstart Templates Provisioning Service(s) Download Installation Packages Access & Post-Config Apps But wait…. There’s more to consider! Server iPXE Out of Band Management (BMC, IPMI, Redfish, etc) O/S Kernel Bootloader O/S ISO Infrastrastructure Config Kickstart as Code Templates Provisioning Service(s) Download Installation Packages Access & Post-Config Apps IaC? Show us some templates! Typical PXE Questions Why is this so fragile? What about PXE over Wifi? What about using a VLAN? Can I dockerize this? What about setting BIOS & RAID? How can I make this faster? How can we Server PXE/iPXE PXE simplify that?!! Small RAM only Footprint Provisioning O/S Inventory At RackN, we’ve been using an in Service(s) reboot memory operating system, “sledgehammer,” based on CentOS. Informed Guided Installation Installation It’s highly optimized to ● Run on nearly any hardware ● Load very quickly ● Collect deep inventory ● Have built-in tools for system tasks like hardware config Image Based Deployment (10x faster!) Server PXE/iPXE PXE RAM only Small O/S Footprint Provisioning Write O/S O/S Image Service(s) To Drive(s) as Archive reboot Informed Machine Installation Init Immutable Provisioning Server PXE PXE/iPXE Highly RAM only Minimal Available O/S Footprint Provisioning Service(s) Config & Machine Attach Disks Initialize Load Apps Container & Containers Registries And now… Advanced Provisioning! ESXi Provisioning Server iPXE O/S Kernel Bootloader O/S ISO Provisioning Config weasel Service(s) Templates restricted Access & CLI/python Apps Control via VMware ESXi VMw APIs Tooling ONIE: Open Network Install Environment Switch Current DHCP Firmware Provisioning Service(s) New HTTP(S) Firmware O/S Image Designed for Embedded Systems where we’re replacing the O/S as a complete image. Does have DHCP options for a startup script. kexec (kernel execute) Server Normal Running O/S Provision Download New Kernel New Kernel kexec Starts Provisioning Without New O/S Service(s) Rebooting kexec (kernel execute) Server Normal Running O/S Provision Download New Kernel New Kernel kexec Provisioning New O/S Service(s) Start kexec iPXE New Normal Installation Provision Without Rebooting Secure Boot Required SIGNED Bootloaders Server DHCP Secured Firmware NextServer & Options Enabled TPM HTTP(S) Trusted Provisioning Bootloader Signed ipxe.efi Service(s) Verified HTTP(S) Trusted O/S Kernel Signed O/S ISO Verified BMC Boot option 1 Server Install BMC Firmware Media Attached O/S Install Provisioning Service(s) Kickstart Download Installation Packages Post-Config Access & Apps BMC Boot option 2 Server Install BMC Firmware Media Bootloader DHCP Provisioning Config Service(s) Kickstart Templates Download Installation Packages Post-Config Access & Apps Thanks! Contact us: Rob Hirschfeld, RackN.com Digital Rebar Behind the Firewall, Self-Service Infrastructure as Code Self-Trials: rebar.digital .
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