YML Reader

This tool allows you to write configurations in YML with extensions to include other files from within your yml and also allows for substitution of ENVIRONMENT variables so that you can build complex configurations but keep the contents of those configurations in separate configuration files.

This is useful for keeping most of your configurations identical for all envionments with only small pieces of the configuration specific to an environment. For example if you had a Kubernetes configuration where you would like to have different disk volumes, say you'd like to have a hostPath for local development but use awsElasticBlockStore for QA and Staging but then use gcePersistentDisk for production you could do something like:

main-containers.yml:

apiVersion: v1
kind: Pod
metadata:
  name: postgres
  labels: 
    name: postgres
spec: 
  containers: 
    -
      image: postgres:9.4
      name: postgres
      ...
      volumeMounts:
        - name: postgres-persistent-storage
          # mount path within the container
          mountPath: /var/lib/postgres
  volumes:
    - !include storage/{{VOLUME_TYPE}}_postgres.yml

storage/development_postgres.yml:

name: postgres-persistent-storage
hostPath:
  path: /private/var/postgres/cs-api-data

storage/staging_postgres.yml:

name: postgres-persistent-storage
awsElasticBlockStore:
  volumeID: aws://my-zone/v123
  fsType: ext4

storage/production_postgres.yml:

name: postgres-persistent-storage
gcePersistentDisk:
  pdName: my-data-disk
  fsType: ext4

Run the following CLI for each:

VOLUME_TYPE=development yml-reader main-containers.yml
VOLUME_TYPE=staging yml-reader main-containers.yml
VOLUME_TYPE=production yml-reader main-containers.yml

###Usages### ####Include#### Using includes you are able to bring in other configuration files to orchestrate multiple sources into a single yml or JSON output. There are 2 types of includes you are able to use within your yml files:

• !include file.yml
  • This will include the file specified and will error if the file does not exist
• !include? file-not-exists.yml
  • This will include the file if it exists but will ignore the file if it does not exist

Environment property substitutions can also be used within the file paths so that you can have specific items brought in based on that environment value. E.g:

foo:
  !include test/{{MY_RUNTIME}}_property.yml

Which would produce the file path test/staging_property.yml if the env variable (MY_RUNTIME) value was set to staging.

####Env#### You can also specify scalar values within your yaml by using the directive ENV. For e.g:

host: !env MY_SERVICE_HOST
description: "This is using host {{MY_SERVICE_HOST}}"

When the env property MY_SERVICE_HOST is set to localhost will produce the output:

{
   "host": "localhost",
   "description": "This is using host localhost"
}

CLI Tool

Using the cli commands you are able to specify a starting file as part of the command or they can be read from STDIN. There are 2 ways of specifying environment variables:

• ENVIRONMENT=staging USER=me yml-reader test/custom-yml-reader/fixtures/include-required/sub-env-var-main-test.yml
• yml-reader -e ENVIRONMENT=staging -e USER=me test/custom-yml-reader/fixtures/include-required/sub-env-var-main-test.yml

Using standard in, you must specify the start directory if including sub files from std in:

• cat test/custom-yml-reader/fixtures/include-required/sub-env-var-main-test.yml | yml-reader -d test/custom-yml-reader/fixtures/include-required/ -e ENVIRONMENT=staging

Outputting back to YML:

• yml-reader -y test/custom-yml-reader/fixtures/include-required/multiple-roots-test.yml

Outputting YML with Root array split up by parameter (defaults: "---")

• yml-reader -y test/custom-yml-reader/fixtures/include-required/multiple-roots-test.yml -s
• yml-reader -y test/custom-yml-reader/fixtures/include-required/multiple-roots-test.yml -s "***"