package config import ( "bytes" "fmt" "io/ioutil" "regexp" "strconv" "strings" "github.com/hashicorp/terraform/config/lang/ast" ) // Funcs is the mapping of built-in functions for configuration. var Funcs map[string]ast.Function func init() { Funcs = map[string]ast.Function{ "file": interpolationFuncFile(), "format": interpolationFuncFormat(), "join": interpolationFuncJoin(), "element": interpolationFuncElement(), "replace": interpolationFuncReplace(), "split": interpolationFuncSplit(), // Concat is a little useless now since we supported embeddded // interpolations but we keep it around for backwards compat reasons. "concat": interpolationFuncConcat(), } } // interpolationFuncConcat implements the "concat" function that // concatenates multiple strings. This isn't actually necessary anymore // since our language supports string concat natively, but for backwards // compat we do this. func interpolationFuncConcat() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString}, ReturnType: ast.TypeString, Variadic: true, VariadicType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { var b bytes.Buffer for _, v := range args { b.WriteString(v.(string)) } return b.String(), nil }, } } // interpolationFuncFile implements the "file" function that allows // loading contents from a file. func interpolationFuncFile() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString}, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { data, err := ioutil.ReadFile(args[0].(string)) if err != nil { return "", err } return string(data), nil }, } } // interpolationFuncFormat implements the "replace" function that does // string replacement. func interpolationFuncFormat() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString}, Variadic: true, VariadicType: ast.TypeAny, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { format := args[0].(string) return fmt.Sprintf(format, args[1:]...), nil }, } } // interpolationFuncJoin implements the "join" function that allows // multi-variable values to be joined by some character. func interpolationFuncJoin() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString, ast.TypeString}, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { var list []string for _, arg := range args[1:] { parts := strings.Split(arg.(string), InterpSplitDelim) list = append(list, parts...) } return strings.Join(list, args[0].(string)), nil }, } } // interpolationFuncReplace implements the "replace" function that does // string replacement. func interpolationFuncReplace() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString, ast.TypeString, ast.TypeString}, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { s := args[0].(string) search := args[1].(string) replace := args[2].(string) // We search/replace using a regexp if the string is surrounded // in forward slashes. if len(search) > 1 && search[0] == '/' && search[len(search)-1] == '/' { re, err := regexp.Compile(search[1 : len(search)-1]) if err != nil { return nil, err } return re.ReplaceAllString(s, replace), nil } return strings.Replace(s, search, replace, -1), nil }, } } // interpolationFuncSplit implements the "split" function that allows // strings to split into multi-variable values func interpolationFuncSplit() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString, ast.TypeString}, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { return strings.Replace(args[1].(string), args[0].(string), InterpSplitDelim, -1), nil }, } } // interpolationFuncLookup implements the "lookup" function that allows // dynamic lookups of map types within a Terraform configuration. func interpolationFuncLookup(vs map[string]ast.Variable) ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString, ast.TypeString}, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { k := fmt.Sprintf("var.%s.%s", args[0].(string), args[1].(string)) v, ok := vs[k] if !ok { return "", fmt.Errorf( "lookup in '%s' failed to find '%s'", args[0].(string), args[1].(string)) } if v.Type != ast.TypeString { return "", fmt.Errorf( "lookup in '%s' for '%s' has bad type %s", args[0].(string), args[1].(string), v.Type) } return v.Value.(string), nil }, } } // interpolationFuncElement implements the "element" function that allows // a specific index to be looked up in a multi-variable value. Note that this will // wrap if the index is larger than the number of elements in the multi-variable value. func interpolationFuncElement() ast.Function { return ast.Function{ ArgTypes: []ast.Type{ast.TypeString, ast.TypeString}, ReturnType: ast.TypeString, Callback: func(args []interface{}) (interface{}, error) { list := strings.Split(args[0].(string), InterpSplitDelim) index, err := strconv.Atoi(args[1].(string)) if err != nil { return "", fmt.Errorf( "invalid number for index, got %s", args[1]) } v := list[index%len(list)] return v, nil }, } }