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