Class: Pcrd::Cutover::Orchestrator

Inherits:
Object
  • Object
show all
Defined in:
lib/pcrd/cutover/orchestrator.rb

Overview

Orchestrates the cutover sequence.

Preconditions (operator’s responsibility):

- Application is in maintenance mode (writes to source have stopped)
- pcrd migrate is running in streaming mode (or was cleanly stopped)

Steps:

1. Verify the migration is at a cuttable phase (backfill complete)
2. Drain remaining replication lag to zero (with timeout)
3. Advance sequences on target
4. Verify row counts match
5. Print cutover report and "READY" signal

Defined Under Namespace

Classes: Result

Instance Method Summary collapse

Constructor Details

#initialize(source_pool:, target_pool:, config:) ⇒ Orchestrator

Returns a new instance of Orchestrator.



26
27
28
29
30
 
# File 'lib/pcrd/cutover/orchestrator.rb', line 26

def initialize(source_pool:, target_pool:, config:)
  @source  = source_pool
  @target  = target_pool
  @config  = config
end

Instance Method Details

#run(on_progress: nil) ⇒ Object

Runs the full cutover sequence. on_progress: optional Proc called with a status string during drain



34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
 
# File 'lib/pcrd/cutover/orchestrator.rb', line 34

def run(on_progress: nil)
  warnings   = []
  table_names = (@config.migrate&.tables || []).map(&:name)

  # 1. Drain remaining lag
  on_progress&.call("Draining replication lag...")
  lag = drain_lag(table_names, on_progress: on_progress)

  # 2. Advance sequences
  on_progress&.call("Advancing target sequences...")
  seq_results = Sequences.new(
    source_pool:   @source,
    target_pool:   @target,
    safety_buffer: @config.cutover&.sequence_buffer || 1_000
  ).advance(table_names)

  # 3. Row count verification
  on_progress&.call("Verifying row counts...")
  row_counts = verify_counts(table_names, warnings)

  passed = row_counts.all? { |_, v| v[:source] == v[:target] }

  Result.new(
    passed:           passed,
    row_counts:       row_counts,
    sequence_results: seq_results,
    lag_at_cutover:   lag,
    warnings:         warnings
  )
end