streamdal/gophercon2021

Reliability Nirvana

GopherCon 2021

This repo contains the various materials used as part of the "Reliability Nirvana" presentation.

Contents:

• ./svc - idempotent sample service
• ./example1 - bare-bones sample producer & consumer
• ./docker-compose.yaml - rabbitmq, etcd and statsd + graphite (for demo visualization)
  • docker-compose.yaml up -d - to bring up all
  • or
  • docker-compose up -d $specific-dependency
• ./assets - config files for graphite, screenshots for this repo

Once docker-compose is finished, you should be able to view the graphite UI by pointing your browser at http://localhost:80 and see something like this:

The orders and notify services will emit the following metrics:

• $service_new_order_ok
  • Emitted by service when an event is processed successfully
• $service_new_order_skipped
  • Emitted by service when an event is skipped

These metrics can be found under the path: Metrics/stats_counts/$service_new_order_*

Demo

1. Basic consume/produce

1. Bring up dependencies
   1. docker-compose up -d
2. Verify dependencies are up
3. Bing up services
   1. cd svc && SERVICE_NAME=order go run *.go
   2. In another terminal: cd svc && SERVICE_NAME=notify go run *.go
4. Publish an event
   1. plumber write rabbit --exchange-name events --input '{"type":"new_order","id":"123"}' --routing-key=foo
5. Observe services consume the event
   1. orders_new_order_ok metric will increase in Graphite UI (http://localhost:80)
   2. notify_new_order_ok metric will increase

2. Recovery - one of the consumers is down (for a while)

1. Bring down notify service (via ctrl-c)
2. Publish another event
3. Observe service orders consume the event
   1. orders_new_order_ok metric will increase
   2. notify_new_order_ok metric will not increase
4. Bring up "notify" service
   1. cd svc && SERVICE_NAME=notify go run *.go
5. See it consume the event
   1. notify_new_order_ok metric will increase on its own

3. Idempotency

1. Publish several events via plumber
2. orders and notify services will both consume and process the messages each time
3. orders_processed and notifications_sent metrics will increase...
4. ^ But this is incorrect - it's the same event - we shouldn't be processing duplicate events
5. Enable etcd usage by restarting services and setting an ENV var:
   1. cd svc && ENABLE_ETCD=true SERVICE_NAME=orders go run *.go
   2. cd svc && ENABLE_ETCD=true SERVICE_NAME=notify go run *.go
6. Publish a single event
7. Watch services consume the event
   1. orders_new_order_ok & notify_new_order_ok will increase
8. Publish an event once more
9. Both services will skip the event because the message id has been seen
   1. orders_new_order_skipped & notify_new_order_skipped metrics will be populated
10. Restart the services and re-emit events
11. Services will instantly skip the message (due to initial cache import)