package funcs import ( "encoding/base64" "fmt" "io/ioutil" "os" "path/filepath" "unicode/utf8" "github.com/bmatcuk/doublestar" "github.com/hashicorp/hcl/v2" "github.com/hashicorp/hcl/v2/hclsyntax" homedir "github.com/mitchellh/go-homedir" "github.com/zclconf/go-cty/cty" "github.com/zclconf/go-cty/cty/function" ) // MakeFileFunc constructs a function that takes a file path and returns the // contents of that file, either directly as a string (where valid UTF-8 is // required) or as a string containing base64 bytes. func MakeFileFunc(baseDir string, encBase64 bool) function.Function { return function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, }, Type: function.StaticReturnType(cty.String), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { path := args[0].AsString() src, err := readFileBytes(baseDir, path) if err != nil { err = function.NewArgError(0, err) return cty.UnknownVal(cty.String), err } switch { case encBase64: enc := base64.StdEncoding.EncodeToString(src) return cty.StringVal(enc), nil default: if !utf8.Valid(src) { return cty.UnknownVal(cty.String), fmt.Errorf("contents of %s are not valid UTF-8; use the filebase64 function to obtain the Base64 encoded contents or the other file functions (e.g. filemd5, filesha256) to obtain file hashing results instead", path) } return cty.StringVal(string(src)), nil } }, }) } // MakeTemplateFileFunc constructs a function that takes a file path and // an arbitrary object of named values and attempts to render the referenced // file as a template using HCL template syntax. // // The template itself may recursively call other functions so a callback // must be provided to get access to those functions. The template cannot, // however, access any variables defined in the scope: it is restricted only to // those variables provided in the second function argument, to ensure that all // dependencies on other graph nodes can be seen before executing this function. // // As a special exception, a referenced template file may not recursively call // the templatefile function, since that would risk the same file being // included into itself indefinitely. func MakeTemplateFileFunc(baseDir string, funcsCb func() map[string]function.Function) function.Function { params := []function.Parameter{ { Name: "path", Type: cty.String, }, { Name: "vars", Type: cty.DynamicPseudoType, }, } loadTmpl := func(fn string) (hcl.Expression, error) { // We re-use File here to ensure the same filename interpretation // as it does, along with its other safety checks. tmplVal, err := File(baseDir, cty.StringVal(fn)) if err != nil { return nil, err } expr, diags := hclsyntax.ParseTemplate([]byte(tmplVal.AsString()), fn, hcl.Pos{Line: 1, Column: 1}) if diags.HasErrors() { return nil, diags } return expr, nil } renderTmpl := func(expr hcl.Expression, varsVal cty.Value) (cty.Value, error) { if varsTy := varsVal.Type(); !(varsTy.IsMapType() || varsTy.IsObjectType()) { return cty.DynamicVal, function.NewArgErrorf(1, "invalid vars value: must be a map") // or an object, but we don't strongly distinguish these most of the time } ctx := &hcl.EvalContext{ Variables: varsVal.AsValueMap(), } // We require all of the variables to be valid HCL identifiers, because // otherwise there would be no way to refer to them in the template // anyway. Rejecting this here gives better feedback to the user // than a syntax error somewhere in the template itself. for n := range ctx.Variables { if !hclsyntax.ValidIdentifier(n) { // This error message intentionally doesn't describe _all_ of // the different permutations that are technically valid as an // HCL identifier, but rather focuses on what we might // consider to be an "idiomatic" variable name. return cty.DynamicVal, function.NewArgErrorf(1, "invalid template variable name %q: must start with a letter, followed by zero or more letters, digits, and underscores", n) } } // We'll pre-check references in the template here so we can give a // more specialized error message than HCL would by default, so it's // clearer that this problem is coming from a templatefile call. for _, traversal := range expr.Variables() { root := traversal.RootName() if _, ok := ctx.Variables[root]; !ok { return cty.DynamicVal, function.NewArgErrorf(1, "vars map does not contain key %q, referenced at %s", root, traversal[0].SourceRange()) } } givenFuncs := funcsCb() // this callback indirection is to avoid chicken/egg problems funcs := make(map[string]function.Function, len(givenFuncs)) for name, fn := range givenFuncs { if name == "templatefile" { // We stub this one out to prevent recursive calls. funcs[name] = function.New(&function.Spec{ Params: params, Type: func(args []cty.Value) (cty.Type, error) { return cty.NilType, fmt.Errorf("cannot recursively call templatefile from inside templatefile call") }, }) continue } funcs[name] = fn } ctx.Functions = funcs val, diags := expr.Value(ctx) if diags.HasErrors() { return cty.DynamicVal, diags } return val, nil } return function.New(&function.Spec{ Params: params, Type: func(args []cty.Value) (cty.Type, error) { if !(args[0].IsKnown() && args[1].IsKnown()) { return cty.DynamicPseudoType, nil } // We'll render our template now to see what result type it produces. // A template consisting only of a single interpolation an potentially // return any type. expr, err := loadTmpl(args[0].AsString()) if err != nil { return cty.DynamicPseudoType, err } // This is safe even if args[1] contains unknowns because the HCL // template renderer itself knows how to short-circuit those. val, err := renderTmpl(expr, args[1]) return val.Type(), err }, Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { expr, err := loadTmpl(args[0].AsString()) if err != nil { return cty.DynamicVal, err } return renderTmpl(expr, args[1]) }, }) } // MakeFileExistsFunc constructs a function that takes a path // and determines whether a file exists at that path func MakeFileExistsFunc(baseDir string) function.Function { return function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, }, Type: function.StaticReturnType(cty.Bool), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { path := args[0].AsString() path, err := homedir.Expand(path) if err != nil { return cty.UnknownVal(cty.Bool), fmt.Errorf("failed to expand ~: %s", err) } if !filepath.IsAbs(path) { path = filepath.Join(baseDir, path) } // Ensure that the path is canonical for the host OS path = filepath.Clean(path) fi, err := os.Stat(path) if err != nil { if os.IsNotExist(err) { return cty.False, nil } return cty.UnknownVal(cty.Bool), fmt.Errorf("failed to stat %s", path) } if fi.Mode().IsRegular() { return cty.True, nil } return cty.False, fmt.Errorf("%s is not a regular file, but %q", path, fi.Mode().String()) }, }) } // MakeFileSetFunc constructs a function that takes a glob pattern // and enumerates a file set from that pattern func MakeFileSetFunc(baseDir string) function.Function { return function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, { Name: "pattern", Type: cty.String, }, }, Type: function.StaticReturnType(cty.Set(cty.String)), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { path := args[0].AsString() pattern := args[1].AsString() if !filepath.IsAbs(path) { path = filepath.Join(baseDir, path) } // Join the path to the glob pattern, while ensuring the full // pattern is canonical for the host OS. The joined path is // automatically cleaned during this operation. pattern = filepath.Join(path, pattern) matches, err := doublestar.Glob(pattern) if err != nil { return cty.UnknownVal(cty.Set(cty.String)), fmt.Errorf("failed to glob pattern (%s): %s", pattern, err) } var matchVals []cty.Value for _, match := range matches { fi, err := os.Stat(match) if err != nil { return cty.UnknownVal(cty.Set(cty.String)), fmt.Errorf("failed to stat (%s): %s", match, err) } if !fi.Mode().IsRegular() { continue } // Remove the path and file separator from matches. match, err = filepath.Rel(path, match) if err != nil { return cty.UnknownVal(cty.Set(cty.String)), fmt.Errorf("failed to trim path of match (%s): %s", match, err) } // Replace any remaining file separators with forward slash (/) // separators for cross-system compatibility. match = filepath.ToSlash(match) matchVals = append(matchVals, cty.StringVal(match)) } if len(matchVals) == 0 { return cty.SetValEmpty(cty.String), nil } return cty.SetVal(matchVals), nil }, }) } // BasenameFunc constructs a function that takes a string containing a filesystem path // and removes all except the last portion from it. var BasenameFunc = function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, }, Type: function.StaticReturnType(cty.String), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { return cty.StringVal(filepath.Base(args[0].AsString())), nil }, }) // DirnameFunc constructs a function that takes a string containing a filesystem path // and removes the last portion from it. var DirnameFunc = function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, }, Type: function.StaticReturnType(cty.String), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { return cty.StringVal(filepath.Dir(args[0].AsString())), nil }, }) // AbsPathFunc constructs a function that converts a filesystem path to an absolute path var AbsPathFunc = function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, }, Type: function.StaticReturnType(cty.String), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { absPath, err := filepath.Abs(args[0].AsString()) return cty.StringVal(filepath.ToSlash(absPath)), err }, }) // PathExpandFunc constructs a function that expands a leading ~ character to the current user's home directory. var PathExpandFunc = function.New(&function.Spec{ Params: []function.Parameter{ { Name: "path", Type: cty.String, }, }, Type: function.StaticReturnType(cty.String), Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) { homePath, err := homedir.Expand(args[0].AsString()) return cty.StringVal(homePath), err }, }) func openFile(baseDir, path string) (*os.File, error) { path, err := homedir.Expand(path) if err != nil { return nil, fmt.Errorf("failed to expand ~: %s", err) } if !filepath.IsAbs(path) { path = filepath.Join(baseDir, path) } // Ensure that the path is canonical for the host OS path = filepath.Clean(path) return os.Open(path) } func readFileBytes(baseDir, path string) ([]byte, error) { f, err := openFile(baseDir, path) if err != nil { if os.IsNotExist(err) { // An extra Terraform-specific hint for this situation return nil, fmt.Errorf("no file exists at %s; this function works only with files that are distributed as part of the configuration source code, so if this file will be created by a resource in this configuration you must instead obtain this result from an attribute of that resource", path) } return nil, err } defer f.Close() src, err := ioutil.ReadAll(f) if err != nil { return nil, fmt.Errorf("failed to read %s", path) } return src, nil } // File reads the contents of the file at the given path. // // The file must contain valid UTF-8 bytes, or this function will return an error. // // The underlying function implementation works relative to a particular base // directory, so this wrapper takes a base directory string and uses it to // construct the underlying function before calling it. func File(baseDir string, path cty.Value) (cty.Value, error) { fn := MakeFileFunc(baseDir, false) return fn.Call([]cty.Value{path}) } // FileExists determines whether a file exists at the given path. // // The underlying function implementation works relative to a particular base // directory, so this wrapper takes a base directory string and uses it to // construct the underlying function before calling it. func FileExists(baseDir string, path cty.Value) (cty.Value, error) { fn := MakeFileExistsFunc(baseDir) return fn.Call([]cty.Value{path}) } // FileSet enumerates a set of files given a glob pattern // // The underlying function implementation works relative to a particular base // directory, so this wrapper takes a base directory string and uses it to // construct the underlying function before calling it. func FileSet(baseDir string, path, pattern cty.Value) (cty.Value, error) { fn := MakeFileSetFunc(baseDir) return fn.Call([]cty.Value{path, pattern}) } // FileBase64 reads the contents of the file at the given path. // // The bytes from the file are encoded as base64 before returning. // // The underlying function implementation works relative to a particular base // directory, so this wrapper takes a base directory string and uses it to // construct the underlying function before calling it. func FileBase64(baseDir string, path cty.Value) (cty.Value, error) { fn := MakeFileFunc(baseDir, true) return fn.Call([]cty.Value{path}) } // Basename takes a string containing a filesystem path and removes all except the last portion from it. // // The underlying function implementation works only with the path string and does not access the filesystem itself. // It is therefore unable to take into account filesystem features such as symlinks. // // If the path is empty then the result is ".", representing the current working directory. func Basename(path cty.Value) (cty.Value, error) { return BasenameFunc.Call([]cty.Value{path}) } // Dirname takes a string containing a filesystem path and removes the last portion from it. // // The underlying function implementation works only with the path string and does not access the filesystem itself. // It is therefore unable to take into account filesystem features such as symlinks. // // If the path is empty then the result is ".", representing the current working directory. func Dirname(path cty.Value) (cty.Value, error) { return DirnameFunc.Call([]cty.Value{path}) } // Pathexpand takes a string that might begin with a `~` segment, and if so it replaces that segment with // the current user's home directory path. // // The underlying function implementation works only with the path string and does not access the filesystem itself. // It is therefore unable to take into account filesystem features such as symlinks. // // If the leading segment in the path is not `~` then the given path is returned unmodified. func Pathexpand(path cty.Value) (cty.Value, error) { return PathExpandFunc.Call([]cty.Value{path}) }