configutil

Documentation

Overview

Copyright (c) 2016-2019 Uber Technologies, Inc.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. Package configutil provides an interface for loading and validating configuration data from YAML files.

Other YAML files could be included via the following directive:

production.yaml: extends: base.yaml

There is no multiple inheritance supported. Dependency tree suppossed to form a directed acyclic graph(DAG).

Values from multiple configurations within the same hierarchy are deep merged

Package support multiple configuraton directories potentially having multiple files with the the same name. In this the we just follow the path in extends and load all the file accroding to the relative directory, i.e configA: base.yaml production.yaml(extends base.yaml), configB: base.yaml the load sequance will be the following: configA(base.yaml), configA(production.yaml)

Note regarding configuration merging:

Array defined in YAML will be overriden based on load sequence.
e.g. in the base.yaml:
     sports:
        - football
     in the development.yaml:
     extends: base.yaml
     sports:
        - basketball
     after the merge:
     sports:
        - basketball  // only keep the latest one

Map defined in YAML will be merged together based on load sequence.
e.g. in the base.yaml:
     sports:
        football: true
     in the development.yaml:
     extends: base.yaml
     sports:
        basketball: true
     after the merge:
     sports:  // combine all the map fields
        football: true
        basketball: true

Index

• Variables
• func FilterCandidates(fname string) ([]string, error)
• func Load(fname string, config interface{}) error
• type Extends
• type ValidationError
  • func (e ValidationError) ErrForField(name string) error
  • func (e ValidationError) Error() string

Variables

var ErrCycleRef = errors.New("cyclic reference in configuration extends detected")

ErrCycleRef is returned when there are circular dependencies detected in configuraiton files extending each other.

var ErrNoFilesToLoad = errors.New("attempt to load configuration with no files")

ErrNoFilesToLoad is returned when you attemp to call LoadFiles without valid file paths.

Functions

func FilterCandidates

func FilterCandidates(fname string) ([]string, error)

FilterCandidates filters candidate config files into only the ones that exist.

func Load

func Load(fname string, config interface{}) error

Load loads configuration based on config file name. If config directory cannot be derived from file name, get it from environment variables.

Types

type Extends

type Extends struct {
	Extends string `yaml:"extends"`
}

Extends define a keywoword in config for extending a base configuration file.

type ValidationError

type ValidationError struct {
	// contains filtered or unexported fields
}

ValidationError is the returned when a configuration fails to pass validation.

func (ValidationError) ErrForField

func (e ValidationError) ErrForField(name string) error

ErrForField returns the validation error for the given field.

func (ValidationError) Error

func (e ValidationError) Error() string