127 lines
3.5 KiB
Go
127 lines
3.5 KiB
Go
package config
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import (
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"bytes"
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"fmt"
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"io/ioutil"
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"strconv"
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"strings"
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"github.com/hashicorp/terraform/config/lang/ast"
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)
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// Funcs is the mapping of built-in functions for configuration.
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var Funcs map[string]ast.Function
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func init() {
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Funcs = map[string]ast.Function{
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"concat": interpolationFuncConcat(),
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"file": interpolationFuncFile(),
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"join": interpolationFuncJoin(),
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"element": interpolationFuncElement(),
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}
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}
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// interpolationFuncConcat implements the "concat" function that
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// concatenates multiple strings. This isn't actually necessary anymore
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// since our language supports string concat natively, but for backwards
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// compat we do this.
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func interpolationFuncConcat() ast.Function {
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return ast.Function{
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ArgTypes: []ast.Type{ast.TypeString},
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ReturnType: ast.TypeString,
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Variadic: true,
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VariadicType: ast.TypeString,
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Callback: func(args []interface{}) (interface{}, error) {
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var b bytes.Buffer
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for _, v := range args {
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b.WriteString(v.(string))
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}
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return b.String(), nil
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},
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}
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}
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// interpolationFuncFile implements the "file" function that allows
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// loading contents from a file.
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func interpolationFuncFile() ast.Function {
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return ast.Function{
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ArgTypes: []ast.Type{ast.TypeString},
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ReturnType: ast.TypeString,
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Callback: func(args []interface{}) (interface{}, error) {
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data, err := ioutil.ReadFile(args[0].(string))
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if err != nil {
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return "", err
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}
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return string(data), nil
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},
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}
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}
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// interpolationFuncJoin implements the "join" function that allows
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// multi-variable values to be joined by some character.
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func interpolationFuncJoin() ast.Function {
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return ast.Function{
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ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
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ReturnType: ast.TypeString,
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Callback: func(args []interface{}) (interface{}, error) {
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var list []string
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for _, arg := range args[1:] {
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parts := strings.Split(arg.(string), InterpSplitDelim)
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list = append(list, parts...)
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}
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return strings.Join(list, args[0].(string)), nil
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},
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}
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}
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// interpolationFuncLookup implements the "lookup" function that allows
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// dynamic lookups of map types within a Terraform configuration.
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func interpolationFuncLookup(vs map[string]ast.Variable) ast.Function {
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return ast.Function{
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ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
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ReturnType: ast.TypeString,
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Callback: func(args []interface{}) (interface{}, error) {
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k := fmt.Sprintf("var.%s.%s", args[0].(string), args[1].(string))
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v, ok := vs[k]
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if !ok {
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return "", fmt.Errorf(
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"lookup in '%s' failed to find '%s'",
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args[0].(string), args[1].(string))
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}
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if v.Type != ast.TypeString {
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return "", fmt.Errorf(
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"lookup in '%s' for '%s' has bad type %s",
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args[0].(string), args[1].(string), v.Type)
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}
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return v.Value.(string), nil
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},
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}
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}
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// interpolationFuncElement implements the "element" function that allows
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// a specific index to be looked up in a multi-variable value. Note that this will
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// wrap if the index is larger than the number of elements in the multi-variable value.
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func interpolationFuncElement() ast.Function {
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return ast.Function{
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ArgTypes: []ast.Type{ast.TypeString, ast.TypeString},
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ReturnType: ast.TypeString,
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Callback: func(args []interface{}) (interface{}, error) {
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list := strings.Split(args[0].(string), InterpSplitDelim)
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index, err := strconv.Atoi(args[1].(string))
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if err != nil {
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return "", fmt.Errorf(
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"invalid number for index, got %s", args[1])
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}
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v := list[index%len(list)]
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return v, nil
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},
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}
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}
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