config

Config

Yaml configuration with template, inspired by Ansible and Viper

Usage

• TODO

Specification

• using golang's template syntax, not ansible, not pongo2
• only support single file, but can have multiple documents separated by ---
• environment variables
  • use env function, i.e. home: {{ env "HOME"}}
• variables
  • special top level key vars is used via var function
  • vars in different documents are merged, while for other top level keys, their value is replaced by latter documents
  • vars in current document can be used in current document, we actually render the template of each document twice, so in vars section you can use previous vars and all the syntax supported by golang's template
• condition (not tested, but golang template should support it)
• loop
  • use the range syntax

Using variables

• TODO: will xkb --target={{ $name }} --port={{ $db.port }} have undesired blank and/or new line?

vars:
    influxdb_port: 8080
    databases:
        - influxdb
        - kairosdb
influxdb:
    port: {{ var "influxdb_port" }}
kairosdb:
    port: {{ env "KAIROSDB_PORT" }}
tests:
{{ range $name := var "databases" -}}
{{ $db := var $name -}}
    - xkb --target={{ $name }} --port={{ $db.port }}
{{ end }
base: {{ env "HOME" }}

Using multiple document

• TODO: example
• TODO: the example in runner actually does not require any template features

YAML parsing problem

• multiple document support, the author said it is easy, but he never tried to solve them,
  • the encoder & decoder PR seems to support multiple documents but I don't understand why it does.
  • Actually it would be interesting to look into how to unmarshal stream data since that is needed for Xephon-B, though for most formats, go already have encoder and decoder
  • (Adopted) A easier way is to split the whole file by --- before put it into go-yaml

Acknowledgement

• https://github.com/spf13/viper
• https://github.com/go-yaml/yaml