105 lines
5.6 KiB
Markdown
105 lines
5.6 KiB
Markdown
---
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title: "Ansible KVM Router Lab Part 3"
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date: 2021-10-16
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draft: false
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tags: ["linux", "kvm", "libvirt", "virsh", "ansible", "bash"]
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authors: ["trent"]
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post: 28
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---
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date: 2021-10-16
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## Introduction
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This is Part 3 of a multi-part series of blog posts for building a
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[router lab](https://github.com/TrentSPalmer/router-lab){target="_blank"}
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automatically using a series of bash scripts and ansible.
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[Ansible KVM Router Lab Part 1](/posts/ansible-kvm-router-lab-part-1/){target="_blank"}
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is an overview.
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In [Ansible KVM Router Lab Part 2](/posts/ansible-kvm-router-lab-part-2/){target="_blank"},
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I break down the script
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[build_vms.bash](https://github.com/TrentSPalmer/router-lab/blob/master/build_vms.bash){target="_blank"}.
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In this post I explain
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[define_bridge_networks.bash](https://github.com/TrentSPalmer/router-lab/blob/master/define_bridge_networks.bash){target="_blank"}
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and
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[shutdown_vms.bash](https://github.com/TrentSPalmer/router-lab/blob/master/shutdown_vms.bash){target="_blank"}
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scripts which are used to construct the lab.
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In [Ansible KVM Router Lab Part 4](/posts/ansible-kvm-router-lab-part-4/){target="_blank"},
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I explain
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[connect_vms_to_bridges.bash](https://github.com/TrentSPalmer/router-lab/blob/master/connect_vms_to_bridges.bash){target="_blank"},
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[start_vms.bash](https://github.com/TrentSPalmer/router-lab/blob/master/start_vms.bash){target="_blank"},
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and [rebuild_known_hosts.bash](https://github.com/TrentSPalmer/router-lab/blob/master/rebuild_known_hosts.bash){target="_blank"}
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scripts which are used to construct the lab.
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In [Ansible KVM Router Lab Part 5](/posts/ansible-kvm-router-lab-part-5/){target="_blank"},
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I explain the ansible playbook tasks used to finish building the lab.
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In [Ansible KVM Router Lab Part 6](/posts/ansible-kvm-router-lab-part-6/){target="_blank"},
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I explain
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[disconnect_vms_from_bridges.bash](https://github.com/TrentSPalmer/router-lab/blob/master/disconnect_vms_from_bridges.bash){target="_blank"},
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[undefine_and_remove_vms.bash](https://github.com/TrentSPalmer/router-lab/blob/master/undefine_and_remove_vms.bash){target="_blank"},
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and [remove_bridge_networks](https://github.com/TrentSPalmer/router-lab/blob/master/remove_bridge_networks.bash){target="_blank"}
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which are used to destroy the lab.
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## `define_bridge_networks.bash`
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The router-lab has two bridge networks, in addition to the initial out-of-band
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network which is used to contact the virtual machines directly.
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### `check_uid "${USER_UID}"`
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[define_bridge_networks.bash](https://github.com/TrentSPalmer/router-lab/blob/master/define_bridge_networks.bash)
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begins by making sure that it is run as a _non-privileged_ user. You can call
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the script with `bash define_bridge_networks.bash`.
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### `function define_bridge_networks()`
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`define_bridge_networks` calls `define_bridge_network` twice, once for each of the
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upper bridge and the lower bridge. `define_bridge_network` parses the output of
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`virsh net-list --all` to determine if the network is defined yet. If not,
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`virsh net-define vm_router_lab_lower_bridge.xml` or
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`virsh net-define vm_router_lab_upper_bridge.xml` are invoked as necessary.
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`define_bridge_network` then recursively calls itself for confirmation.
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Links for
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[vm_router_lab_upper_bridge.xml](https://github.com/TrentSPalmer/router-lab/blob/master/vm_router_lab_upper_bridge.xml){target="_blank"}
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and
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[vm_router_lab_lower_bridge.xml](https://github.com/TrentSPalmer/router-lab/blob/master/vm_router_lab_lower_bridge.xml){target="_blank"}.
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### `function start_bridge_networks()`
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`start_bridge_networks` calls `start_bridge_network` twice, once for each of the
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upper and the lower bridge. `start_bridge_network` in turn parses the output of
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`virsh net-info vm_router_lab_upper_bridge` and/or `virsh net-info vm_router_lab_lower_bridge`
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to determine if the cooresponding network is running, and if not invokes
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`virsh net-start vm_router_lab_upper_bridge` or `virsh net-start vm_router_lab_lower_bridge`,
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and then recursively calls itself again for confirmation.
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### `function autostart_bridge_networks()`
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`autostart_bridge_networks` is nearly identical to `start_bridge_networks`, but
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`virsh net-autostart vm_router_lab_upper_bridge` or `virsh net-autostart vm_router_lab_lower_bridge`,
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are invoked in order to mark the cooresponding network to autostart.
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## `shutdown_vms.bash`
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After creating the upper and lower bridge networks, it is necessary to shut down
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the lab clients before connecting the lab clients to the bridge networks. This is
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because network interfaces must be _permanently_ added to the lab client definitions.
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### `check_uid "${USER_UID}"`
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[shutdown_vms.bash](https://github.com/TrentSPalmer/router-lab/blob/master/shutdown_vms.bash)
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begins by making sure that it is run as a _non-privileged_ user. You can call
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the script with `bash shutdown_vms.bash`.
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### `function shutdown_vms()`
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`shutdown_vms` simultaneously calls `shutdown_vm` on the entire MACHINES array.
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`shutdown_vm` in turn parses the output of `virsh list --state-running` to determine if
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the virtual machine is running, and if so invokes `virsh shutdown <vm>`. `shutdown_vm`
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then recursively calls itself to confirm that the virtual machine is indeed shut down.
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## To Be Continued
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In [Ansible KVM Router Lab Part 4](/posts/ansible-kvm-router-lab-part-4/){target="_blank"},
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I explain
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[connect_vms_to_bridges.bash](https://github.com/TrentSPalmer/router-lab/blob/master/connect_vms_to_bridges.bash){target="_blank"},
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[start_vms.bash](https://github.com/TrentSPalmer/router-lab/blob/master/start_vms.bash){target="_blank"},
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and
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[rebuild_known_hosts.bash](https://github.com/TrentSPalmer/router-lab/blob/master/rebuild_known_hosts.bash){target="_blank"}
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scripts which are used to construct the lab.
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