packer-cn/packer/template.go

123 lines
2.9 KiB
Go

package packer
import (
"encoding/json"
"fmt"
)
// The rawTemplate struct represents the structure of a template read
// directly from a file. The builders and other components map just to
// "interface{}" pointers since we actually don't know what their contents
// are until we read the "type" field.
type rawTemplate struct {
Name string
Builders []map[string]interface{}
Provisioners []map[string]interface{}
Outputs []map[string]interface{}
}
// The Template struct represents a parsed template, parsed into the most
// completed form it can be without additional processing by the caller.
type Template struct {
Name string
Builders map[string]rawBuilderConfig
}
// The rawBuilderConfig struct represents a raw, unprocessed builder
// configuration. It contains the name of the builder as well as the
// raw configuration. If requested, this is used to compile into a full
// builder configuration at some point.
type rawBuilderConfig struct {
builderName string
rawConfig interface{}
}
// ParseTemplate takes a byte slice and parses a Template from it, returning
// the template and possibly errors while loading the template.
func ParseTemplate(data []byte) (t *Template, err error) {
var rawTpl rawTemplate
err = json.Unmarshal(data, &rawTpl)
if err != nil {
return
}
t = &Template{}
t.Name = rawTpl.Name
t.Builders = make(map[string]rawBuilderConfig)
for _, v := range rawTpl.Builders {
rawType, ok := v["type"]
if !ok {
// TODO: Missing type error
return
}
// Attempt to get the name of the builder. If the "name" key
// missing, use the "type" field, which is guaranteed to exist
// at this point.
rawName, ok := v["name"]
if !ok {
rawName = v["type"]
}
// TODO: Error checking if we can't convert
name := rawName.(string)
typeName := rawType.(string)
// Check if we already have a builder with this name and record
// an error.
_, ok = t.Builders[name]
if ok {
// TODO: We already have a builder with this name
return
}
t.Builders[name] = rawBuilderConfig{typeName, v}
}
return
}
// BuildNames returns a slice of the available names of builds that
// this template represents.
func (t *Template) BuildNames() []string {
names := make([]string, len(t.Builders))
i := 0
for name, _ := range t.Builders {
names[i] = name
i++
}
return names
}
// Build returns a Build for the given name.
//
// If the build does not exist as part of this template, an error is
// returned.
func (t *Template) Build(name string, bf BuilderFunc) (b Build, err error) {
builderConfig, ok := t.Builders[name]
if !ok {
err = fmt.Errorf("No such build found in template: %s", name)
return
}
builder, err := bf(builderConfig.builderName)
if err != nil {
return
}
if builder == nil {
err = fmt.Errorf("Builder not found: %s", name)
return
}
b = &coreBuild{
name: name,
builder: builder,
rawConfig: builderConfig.rawConfig,
}
return
}