Add session shutdown logic to controller when drained

[martinsander00]

Resolves: #2485

Summary of Changes

• Added logic to tunnel.tmpl that shuts down user BGP, IBGP sessions, MSDP neighbors, and ISIS when device.status is Drained
• Added test case and fixture file to verify drained device configuration
• This implements the device maintenance workflow from RFC-12 (Network Provisioning Framework)

Testing Verification

• Added unit test render_drained_device_config_successfully that verifies shutdown commands are included in rendered config when device status is Drained

[Copilot]

Pull request overview

This PR implements device maintenance workflow by adding session shutdown logic when a device status is set to "Drained". It introduces a new DeviceStatusDrained state and modifies the controller template to automatically shut down BGP sessions, MSDP neighbors, and ISIS routing when a device enters this maintenance state.

• Added DeviceStatusDrained status constant to the device status enumeration
• Modified tunnel.tmpl to conditionally shutdown routing protocols (BGP, MSDP, ISIS) when device status is "drained"
• Added comprehensive test coverage with fixture file to verify drained device configuration

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
smartcontract/sdk/go/serviceability/state.go	Adds new DeviceStatusDrained constant and string representation
controlplane/controller/internal/controller/templates/tunnel.tmpl	Implements conditional shutdown logic for routing protocols based on device status
controlplane/controller/internal/controller/render_test.go	Adds test case for drained device configuration rendering
controlplane/controller/internal/controller/fixtures/base.config.drained.txt	Provides expected output fixture for drained device test
CHANGELOG.md	Documents the new feature

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[ben-malbeclabs]

@martinsander00 - what happens when a device becomes active again? From what I can tell from the code, there is no logic to run no neighbor IP_ADDRESS shutdown or to run no shutdown for MSDP peerings when reverting back to activated state. We need to unwind the commands ran when exiting the drained state.

[nikw9944]

From what I can tell from the code, there is no logic to run no neighbor IP_ADDRESS shutdown or to run no shutdown for MSDP peerings when reverting back to activated state.

I believe the "no router msdp" should take care of this for msdp, but the same issue exists for the isis overload bit, we need to add "no router isis" to handle that.

Also it would be good to un-drain the device in the e2e test to prove it works.

[nikw9944]

Can you put the ! on its own line to make it more readable? Also I think there's an extra space before "set-overload-bit".

{{ if eq $.Device.Status.String "hard-drained" }}   set-overload-bit
{{ end }}
!

[ben-malbeclabs]

From what I can tell from the code, there is no logic to run no neighbor IP_ADDRESS shutdown or to run no shutdown for MSDP peerings when reverting back to activated state.

I believe the "no router msdp" should take care of this for msdp, but the same issue exists for the isis overload bit, we need to add "no router isis" to handle that.

@martinsander00 note that we can't do the same 'no router bgp` as we don't fully own the configuration for BGP i.e. the contributor often adds their own configuration.