89 lines
2.7 KiB
Go
89 lines
2.7 KiB
Go
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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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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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},
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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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path := args[0].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.String), fmt.Errorf("failed to expand ~: %s", 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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src, err := ioutil.ReadFile(path)
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if err != nil {
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// ReadFile does not return Terraform-user-friendly error
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// messages, so we'll provide our own.
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if os.IsNotExist(err) {
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return cty.UnknownVal(cty.String), fmt.Errorf("no file exists at %s", path)
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}
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return cty.UnknownVal(cty.String), fmt.Errorf("failed to read %s", path)
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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), 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; to read arbitrary bytes, use the filebase64 function instead", path)
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}
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return cty.StringVal(string(src)), nil
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}
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},
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})
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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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// 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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