Change config to yaml

[zhilingc]

Is your feature request related to a problem? Please describe.
Configuration for feast is currently done using environment variables only. As the number of parameters grows in size, this method of configuring the deployment becomes increasingly unwieldy.

Describe the solution you'd like
We want to move away from KVs, which are limited when it comes to nested config, eg. for job options. Currently we set it as a json string.

Describe alternatives you've considered
If we use yaml, it would potentially look something like this:

---
# CORE CONFIG #
grpc.port: 6565
http.port: 8080
feast.jobs:
  coreUri: localhost:6565
  runner: DataflowRunner
  options:
    project: my-dataflow-runner-project
    region: asia-east1
    tempLocation: gs://feast-temp-bucket #also required for bq ingestion
    subnetwork: regions/asia-east1/subnetworks/default
  executable: feast-ingestion.jar
  errorsStore:
    type: file.json
    options:
      path: gs://feast-errors
  monitoring:
    period: 5000
    initialDelay: 600000
    statsd:
      host: localhost
      port: 8125

# DB CONFIG #
spring.jpa.properties.hibernate.format_sql: true
spring.datasource.url: "jdbc:postgresql://localhost:5432/postgres"
spring.datasource.username: postgres
spring.datasource.password: password
spring.jpa.hibernate.naming.physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
spring.jpa.hibernate.ddl-auto: update

# APP METRICS #
management.metrics.export.simple.enabled: false
management.metrics.export.statsd.enabled: true
management.metrics.export.statsd.host: localhost
management.metrics.export.statsd.port: 8125

We can still continue to support env vars for overriding config.

[zhilingc]

@woop @tims thoughts?

[woop]

I think it's worth doing. Easier to work with, and easier to read.

Why would we have some keys nested and some flattened? Why not all nested like:

spring:
  jpa:
    properties:
      format_sql: true
    hibernate
      naming
        physical-strategy: blah
      ddl-auto: update
  datasource:
    url:  "jdbc:postgresql://localhost:5432/postgres"
    username: postgres
    password: password

instead of

spring.jpa.properties.hibernate.format_sql: true
spring.datasource.url: "jdbc:postgresql://localhost:5432/postgres"
spring.datasource.username: postgres
spring.datasource.password: password
spring.jpa.hibernate.naming.physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
spring.jpa.hibernate.ddl-auto: update

[zhilingc]

yeah, that works too.

[tims]

yaml sounds good to me