L7 - Cloud Monitoring

Question 1

Why monitor?

Answer 1

To make best use of your rented resources to reduce your costs and increase satisfaction of the users of your service

Question 2

observable system

Answer 2

one that exposes enough data about itself so that generating information (finding answers to questions yet to be formulated) and easily accessing this information becomes simple

Question 3

monitoring

Answer 3

process of collecting status information of applicaitons and resources; the data can be used to observe application and infrastructure

Question 4

monitoring system

Answer 4

consists of all components for gathering monitoring data at runtime

Question 5

2 ways to create information

Answer 5

• proactively: through continuous analysis for triggering alarms or to give an overview of the status of the system
• reactively: triggering through events such as incidents (e.g. root cause analysis and autoscaling)

Question 6

What is the purpose of monitoring at the infrastructure level?

Answer 6

• resource management
• incident detection
• root cause analysis
• metering for payment
• auditing

Question 7

What is the purpose of monitoring at application level?

Answer 7

• performance analysis
• resource management
• failure detection and resolution
• SLA verification
• auditing

Question 8

How does monitoring take place in a parallel system?

Answer 8

• batch system
• data are collected during an application run
• analysis happens post mortem
• execution is reproducable

Question 9

How does monitoring take place in the cloud?

Answer 9

• interactive system
• data are continuously produced - realtime data
• realtime analysis
• data used for immediate action or to study past system behavior

Question 10

3 pillars of monitoring

Answer 10

• metrics
• logs
• traces

Question 11

4 important metrics in monitoring

Answer 11

• latency
• throughput or traffic
• error rate
• utilization or saturation

Question 12

What is latency

Answer 12

• time it takes to service a request
• selectively measures successful or error requests

Question 13

What is throughput or traffic?

Answer 13

• web services: requests/second
• streaming system: network I/O rate or concurrent sessions
• database: transaction/second or retrievals per second

Question 14

What is the error rate?

Answer 14

• rate of requests that fail

Question 15

What is utilization or saturation?

Answer 15

• percentage of capacity
• CPU, memory, I/O

Question 16

For what are metrics collected for Microservices?

Answer 16

Autoscaling, performance tuning

Question 17

What for are metrics collected for the platform like K8s or Docker?

Answer 17

container distribution, autoscaling VM cluster

Question 18

What are metrics collected for the infrastructure?

Answer 18

• root cause analysis

Question 19

For what are metrics collected for the hardware?

Answer 19

management of VMs

Question 20

Monitoring system requirements

Answer 20

• comprehensive
• low intrusion
• extensibility
• scalability
• elasticity
• accuracy

Question 21

What is Blackbox Monitoring?

Answer 21

• the monitoring system is handled as a black box
• no data are gained from inside of the system
• e.g. only the request interface of a service is visible. Nothing about the internal structure

from internet:
Black box monitoring refers to the monitoring of servers with a focus on areas such as disk space, CPU usage, memory usage, load averages, etc.

Question 22

What is whitebox monitoring?

Answer 22

• data is also from inside of the system
• this gives more context and more detailed insights
• e.g. internal organization of a service is visible

e.g. Performing advanced detection of behavior we don’t expect to see, such as a user not going through the normal steps you’d expect when signing into your application or resetting a password.

Question 23

Why is there overhead in monitoring?

Answer 23

• instrumentation
• computation for aggregations
• memory overhead for buffering
• time to push to disk or transfer to collector
• storage overhead for long-term storage

Question 24

What is instrumentation?

Answer 24

Instrumentation is the process of adding code to your application so you can understand its inner state

Question 25

What does overhead lead to

Answer 25

intrusion

Question 26

How can overhead in monitoring be reduced?

Answer 26

• number of metrics
• measurement frequency
• representation
• batching
• sampling
• long-term coarsening

Question 27

What is a log?

Answer 27

sequence of immutable records of discrete events

Question 28

What can an event log be composed of?

Answer 28

• plaintext = most common format of logs
• structured = much evangelized, typically JSON
• binary = think logs in the Protobuf format

Question 29

What is ELK Stack?

Answer 29

ELK is the acronym for three open-source projects:
- Elasticsearch: search and analytics engine
- Logstash: server-side data processing pipeline
- Kibana: lets users visualize data with charts and graphs

Question 30

What is Elastic Stack

Answer 30

next evolution of ELK Stack

= the open source, distributed, RESTful, JSON-based search engine. Easy to use, scalable and flexible, it earned hyper-popularity among users and a company formed around it, you know, for search.
ELK + Beats and X-Pack