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|
package config
import (
"errors"
"fmt"
"io/ioutil"
"gopkg.in/yaml.v2"
)
// DefaultConfig contains YAML that is applied before the user's
// configuration.
//
const DefaultConfig = `---
lives:
in: /srv/app
as: somebody
uid: 65533
gid: 65533
runs:
as: runuser
uid: 900
gid: 900`
// ResolveIncludes iterates over and recurses through a given variant's
// includes to build a flat slice of variant names in the correct order by
// which they should be expanded/merged. It checks for both the existence of
// included variants and maintains a recursion stack to protect against
// infinite loops.
//
// Variant names found at a greater depth of recursion are first and siblings
// last, the order in which config should be merged.
//
func ResolveIncludes(config *Config, name string) ([]string, error) {
stack := map[string]bool{}
includes := []string{}
var resolve func(string) error
resolve = func(name string) error {
if instack, found := stack[name]; found && instack {
return errors.New("variant expansion detected loop")
}
stack[name] = true
defer func() { stack[name] = false }()
variant, found := config.Variants[name]
if !found {
return fmt.Errorf("variant '%s' does not exist", name)
}
for _, include := range variant.Includes {
if err := resolve(include); err != nil {
return err
}
}
// Appending _after_ recursion ensures the correct ordering
includes = append(includes, name)
return nil
}
err := resolve(name)
return includes, err
}
// ExpandVariant merges a named variant with a config. It also attempts to
// recursively expand any included variants in the expanded variant.
//
func ExpandVariant(config *Config, name string) (*VariantConfig, error) {
expanded := new(VariantConfig)
expanded.CommonConfig.Merge(config.CommonConfig)
includes, err := ResolveIncludes(config, name)
if err != nil {
return nil, err
}
for _, include := range includes {
expanded.Merge(config.Variants[include])
}
return expanded, nil
}
// ReadConfig unmarshals the given YAML bytes into a new Config struct.
//
func ReadConfig(data []byte) (*Config, error) {
var config Config
yaml.Unmarshal([]byte(DefaultConfig), &config)
err := yaml.Unmarshal(data, &config)
if err != nil {
return nil, err
}
err = Validate(config)
return &config, err
}
// ReadConfigFile unmarshals the given YAML file contents into a Config
// struct.
//
func ReadConfigFile(path string) (*Config, error) {
data, err := ioutil.ReadFile(path)
if err != nil {
return nil, err
}
return ReadConfig(data)
}
|
