Lessons from App #1
- The big challenge in microservices is data
- Different ways to share data between services. We are going to focus on async communication
- Async communication focuses on communicating changes using events sent to an event bus
- Async communication encourages each service to be 100% self-sufficient. Relatively easy to handle temporary downtime or new service creation
- Docker makes it easier to package up services
- Kubernetes is a pain to setup, but makes it really easy to deploy + scale services
| Painful Things from App #1 | Solutions! |
|---|---|
| Lots of duplicated code! | Build a central library as an NPM module to share code between our different projects |
| Really hard to picture the flow of events between services | Precisely define all of our events in this shared library. |
| Really hard to remember what properties an event should have | Write everything in Typescript. |
| Really hard to test some event flows | Write tests for as much as possible/reasonable |
| My machine is getting laggy running kubernetes and everything else... | Run a k8s cluster in the cloud and develop on it almost as quickly as localz |
| What if someone created a comment after editing 5 others after editing a post while balancing on a tight rope.... | Introduce a lot of code to handle concurrency issues |
- Users can list a ticket for an event (concert, sports) for sale
- Other users can purchase this ticket
- Any user can list tickets for sale and purchase tickets
- When a user attempts to purchase a ticket, the ticket is 'locked' for 15 minutes. The user has 15 minutes to enter their payment info.
- While locked, no other user can purchase the ticket. After 15 minutes, the ticket should 'unlock'
- Ticket prices can be edited if they are not locked
- We are creating a separate service to manage each type of resource
- Should we do this for every microservices app?
- Probably not? Depends on your use case, number of resources, business logic tied to each resource, etc
- Perhaps 'feature-based' design would be better
cd sections-05/ticketing/auth/
docker build -t chesterheng/auth .
docker login
docker push chesterheng/auth
cd ../infra/k8s/
kubectl apply -f auth-depl.yaml
kubectl rollout restart deployment auth-depl
kubectl get deployment
kubectl get pod
kubectl logs auth-depl-7c7879db66-mwz79
kubectl describe pod auth-depl-7c7879db66-mwz79
kubectl exec -it auth-depl-7c7879db66-mwz79 -- cat index.js
kubectl get servicesSee ticketing/skaffold.yaml
cd section-05/ticketing/
skaffold devkubectl get ingress
kubectl describe ingress ingress-serviceHosts File
- Open hosts file
code /etc/hosts- Add 127.0.0.1 ticketing.dev to hosts file
Security Warning
- Goto Chrome - https://ticketing.dev/api/users/currentuser
- Unskippable HTTPS warning in Chrome?
- type thisisunsafe