# PR#101: A tool compares and syncs the host configs on the Werkator host

> **WARNING:** This document describes only the change applied in this PR.
> It may already be outdated once the next PR is merged.
> Historic PR documentation is not maintained along with new PRs; treat it as a snapshot.

## Problem

Each reviewed repository has its host config twice:
as `config/<repo>.toml` in werkrevisor, and inline as `WERKREVISOR_CONFIG_TOML` in its machine config on mih09,
`~/<repo>/.git/werkator/.werkator.yml`.
The machine config also holds tokens, so nobody may print it.
For PR#100, a throwaway script compared and replaced the block and printed only line numbers;
no tool shows whether the other machine configs still match their files.

## Non-Goals

- No change of the tokens or of the build definition in a machine config.
- No automatic sync after a merge.

## Specification

### Feature: sync the inline host config without printing it

#### Scenario#101.01: compare

So that the operator sees a drift without seeing a token.

- **Given** a machine config whose inline host config differs from `config/<repo>.toml` in two lines
- **When** the operator runs `tools/sync-host-config <ssh-target> <repo>`
- **Then** the tool prints the numbers of the two lines and the names of their keys, no value, and exits with 1

##### Verified by

- [test_sync_host_config.HostConfigBlockTest.test_check_prints_only_line_numbers_and_key_names](../../tests/test_sync_host_config.py)
- [test_sync_host_config.HostConfigBlockTest.test_a_changed_comment_changes_no_key](../../tests/test_sync_host_config.py)
- [test_sync_host_config.HostConfigBlockTest.test_a_key_only_on_the_host](../../tests/test_sync_host_config.py)
- [test_sync_host_config.SyncHostConfigScriptTest.test_check_and_apply_over_one_connection_each](../../tests/test_sync_host_config.py)

#### Scenario#101.02: replace

So that a changed host config reaches the review with one command.

- **Given** the same machine config
- **When** the operator runs `tools/sync-host-config --apply <ssh-target> <repo>`
- **Then** the inline host config equals the file, every other line stays, and a backup holds the old version

##### Verified by

- [test_sync_host_config.HostConfigBlockTest.test_apply_replaces_the_block_and_keeps_every_other_line](../../tests/test_sync_host_config.py)
- [test_sync_host_config.HostConfigBlockTest.test_a_block_with_a_chomping_indicator](../../tests/test_sync_host_config.py)

#### Scenario#101.03: no inline host config

So that a machine config of another layout stays untouched.

- **Given** a machine config without `WERKREVISOR_CONFIG_TOML`
- **When** the operator runs the tool with `--apply`
- **Then** the tool reports the missing block for this repository and changes nothing

##### Verified by

- [test_sync_host_config.HostConfigBlockTest.test_a_machine_config_without_the_block_stays_unchanged](../../tests/test_sync_host_config.py)
- [test_sync_host_config.HostConfigBlockTest.test_a_missing_machine_config](../../tests/test_sync_host_config.py)

#### Scenario#101.04: backups

So that the backups do not pile up.

- **Given** two earlier backups of the tool
- **When** the tool replaces the inline host config again
- **Then** only the two newest backups stay

##### Verified by

- [test_sync_host_config.HostConfigBlockTest.test_only_the_two_newest_backups_stay](../../tests/test_sync_host_config.py)

## Solution

`tools/host_config_block.py` runs on the Werkator host and gets the files as JSON on stdin.
It finds the block below `WERKREVISOR_CONFIG_TOML: |`, also with `|-` or `|+`, compares it line by line with the file,
and names the keys of both TOML texts by kind: changed, only in the file, only on the host.
With `apply` it writes the file into the block with the indentation of the block, and keeps every other line.

`tools/sync-host-config` sends the module and the files over one ssh connection,
and retries a refused one like `tools/deploy-rootfs`.
Its tests run it with a fake `ssh` that runs the remote command locally.

A first check on mih09 found:

- werkrevisor, werkregie and werkbaum: equal.
- werkator and werkcrappit: only keys that their own `.werkrevisor.toml` sets are missing, as intended.
- werkprobe: on the host, `[engine] model_role`, `[hard_yellow] judged_paths` and `[path_judge] judge` and `scope` are set,
  and `[hard_yellow] paths` differs; `config/werkprobe.toml` lacks these changes.

## Additional Changes

- The operations document names version 0.41.0.

## Open Questions

None.

## Follow-up PRs

- Bring `config/werkprobe.toml` and the machine config of werkprobe together; the human decides which one is right.