## Why
Migrate the VM puppet agents off the legacy VM puppetmasters onto the new puppet-on-kubernetes servers, one wave at a time and reversible without re-enrolment.
Changing `server`/`ca_server` alone is insufficient: each agent's ssldir holds a client certificate signed by the **old** CA, which the new k8s CA neither trusts nor recognises. Migrated nodes switch to a **fresh ssldir**, so the agent generates a new key + CSR on its next run (autosigned immediately by the k8s CA, which runs `autosign = true`), pulls its catalog from the new compilers, and leaves the old CA-signed creds intact on disk for rollback.
The reconfiguration catalog is compiled by the **old** server (the node still points there when it applies the change). `profiles::puppet::client` rewrites `puppet.conf` with the new endpoints + ssldir and notifies `Service['puppet']`, so the very next agent run lands on k8s.
**Single-boolean design (reworked):** cutover is now driven by one hiera key. `profiles::puppet::migrate` ships wired into `profiles::base` with `enabled => false`, so every node evaluates it but nothing changes until the boolean is flipped. `profiles::puppet::client` includes migrate and folds the migrate endpoints into the effective values it renders. Flip `profiles::puppet::migrate::enabled: true` at any hiera layer (node/role/common) to migrate a target -- no other keys required.
## Changes
- `profiles::base` (`site/profiles/manifests/base.pp`): `include profiles::puppet::migrate` alongside the other puppet profiles (ships disabled).
- `profiles::puppet::migrate` (`site/profiles/manifests/puppet/migrate.pp`): unchanged params (`enabled=false`, `new_server`, `new_ca_server`, `new_ssldir`); when enabled and the node is not a puppetmaster it owns the fresh ssldir directory. Class-header runbook rewritten for the single-boolean flow. No longer opt-in via `hiera_include`.
- `profiles::puppet::client` (`site/profiles/manifests/puppet/client.pp`): `include profiles::puppet::migrate` and compute `$effective_server` / `$effective_ca_server` / `$effective_report_server` / `$effective_ssldir`, feeding those to the template. Keeps the existing optional `$ssldir` / `$report_server` params as manual overrides.
- `puppet.conf.erb`: render from the `@effective_*` vars.
## Precedence
- **ssldir / report_server** (`Optional`, default `undef`): explicit `profiles::puppet::client::ssldir` / `::report_server` in hiera wins; else the migrate-derived value when `enabled`; else the legacy default (ssldir omitted -> puppet default; report_server -> effective server).
- **server / ca_server** (`String`, no undef sentinel): the migrate endpoint wins while `enabled => true`; otherwise the client param (legacy default unless set explicitly). To pin a bespoke server, leave `enabled => false` for that target and set `profiles::puppet::client::server` directly.
- No include cycle: migrate.pp never references client.pp; its guard uses `$facts['enc_role']`.
## Runbook
- **Canary (one node)** -> `hieradata/nodes/<certname>.yaml`: `profiles::puppet::migrate::enabled: true`
- **Wave (a role)** -> `hieradata/roles/<t1>/<t2>[/<t3>].yaml`: `profiles::puppet::migrate::enabled: true`
- **Estate flip** -> `hieradata/common.yaml`: `profiles::puppet::migrate::enabled: true`
- **Rollback** -> remove the key (or set `false`) at that layer; next run rewrites puppet.conf back to the legacy server + legacy ssldir (original CA-signed cert intact).
- The k8s endpoints (`new_server` / `new_ca_server` / `new_ssldir`) are `profiles::puppet::migrate` param defaults; override them in hiera if the k8s names change.
## Verification
- Render comparison: unmigrated node renders a **byte-identical** `puppet.conf` to `develop` (diff empty). Migrated render (only `enabled: true`) emits `server`/`ca_server`/`report_server` = k8s endpoints and `ssldir = /etc/puppetlabs/puppet/ssl-k8s`.
- `puppet-lint` (repo args `--no-80chars-check --no-documentation-check --no-puppet_url_without_modules-check --fail-on-warnings`): clean on all 3 manifests.
- `puppet parser validate`: OK. ERB syntax: OK. Repo pre-commit hooks (erb-validate, puppet-lint, puppet-validate): all Passed.
Reviewed-on: #493
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
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