- How do you access application logs?
cf logs APP_NAME
- What are the components of the Loggregator system?
- Metron - Forward logs to the Loggregator subsytem
- Doppler - gather logs from Metron
- Traffic Controller - handles client requests for logs
- Firehose - a websocket endpoint that exposes app logs, container metrics and ER component metrics
- Nozzles - consume the firehose output
- How do you scale an application manually?
cf scale <APP_NAME> -m -i <Instance_COUNT>
- What are the four levels of high-availability provided by PCF?
- BOSH detects and recreates failed VMs
- BOSH also detects and restarts failed processes
- Application instances are automatically spread -- Across different Cells -- Across Cells in different Availability Zones
- CF Converger detects if an application instance has failed and restarts it
- What is the difference between scaling up and scaling out?
- scale up (vertically) increases the disk space limit or memory limit of all instances of an application. It requires downtime as the container is recreated.
- scale out (horizontally) increases the number of instances of an application by creating or destroying them. It requires no downtime.
- What are some fundamental changes impacting application design and delivery?
- Distributed computing
- Ephemeral infrastructure
- Immutable infrastructure
- What is a modern methodology for delivering cloud based applications?
Twelve-factor app
- How are logs handled in a Twelve-factor app?
As event streams
- True or false, Garden is an interface with many implementations.
True, there's Linux and Windows and more on the way
- Which component of the Elastic runtime exposes an API for users to manage applications?
Cloud controller
- What are the four levels of high availability that keep your applications running?
- Availability zones
- BOSH managed processes
- Failed VMs - any VM that BOSH deploys will be recreated if you enable resurrector
- Self healing application instances handled by the brain within Diego
- Where should you write your application logs?
- To Standard Out and Standard Error
- What are some of the different origin codes that were seen in the log?
- cf logs
- API for cloud controller
- stage for stating
- cell for running applications
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What did you think about accessing the logs? How is that different from what you do today?
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What is the difference between scaling out versus scaling up?
Scaling up requires down time to recreate the container Scaling horizontally requires no downtime
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How do you recover failed application instances today? What happens if the underlying platform fails? How do you recover from that?
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How could you tell if your application has been crashing?
Look at the logs, but probably the best place to go is cf events