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Merged
sagikazarmark merged 19 commits into from
Oct 8, 2025
+147 −49
Merged

Return not found error if setting config #2027

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3f8aad8
fix: return not found error if setting config
spacez320 Jun 15, 2025
7f37f34
style: gofumpt
spacez320 Aug 8, 2025
00c48eb
refactor: segregate errors, config file not found interface
spacez320 Aug 14, 2025
5ec9e04
style: clean-up
spacez320 Aug 14, 2025
b3382e1
refactor: apply suggestions from code review
spacez320 Aug 16, 2025
97b9da7
refactor: better naming, return original error for finder
spacez320 Aug 17, 2025
3dd8fe3
docs: add explanation on read in config errors
spacez320 Aug 17, 2025
77db77a
style: clean-up
spacez320 Aug 17, 2025
95f1e39
style: better test name
spacez320 Aug 17, 2025
906777c
docs: better file not found example, remove file not found interface
spacez320 Aug 17, 2025
1e717eb
style: apply suggestions from code review
spacez320 Aug 18, 2025
caf33e2
refactor: redundant fields for file search error, interface, syscall opt
spacez320 Aug 18, 2025
823128e
style: variable naming, readme conforming
spacez320 Aug 18, 2025
e956e2f
fix: wrap file not found error
spacez320 Aug 18, 2025
a38b309
style: clean-up
spacez320 Aug 18, 2025
66a6831
style: better naming
spacez320 Aug 18, 2025
b33c39c
refactor: apply review comments
sagikazarmark Sep 26, 2025
1a90a66
refactor: clean-ups
spacez320 Oct 3, 2025
b24b2a7
docs: update comment on deprecated error
sagikazarmark Oct 8, 2025
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13 changes: 8 additions & 5 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -131,12 +131,15 @@ if err != nil { // Handle errors reading the config file
You can handle the specific case where no config file is found like this:

```go
var fileLookupError viper.FileLookupError
if err := viper.ReadInConfig(); err != nil {
if _, ok := err.(viper.ConfigFileNotFoundError); ok {
// Config file not found; ignore error if desired
} else {
// Config file was found but another error was produced
}
if errors.As(err, &fileLookupError) {
// Indicates an explicitly set config file is not found (such as with
// using `viper.SetConfigFile`) or that no config file was found in
// any search path (such as when using `viper.AddConfigPath`)
} else {
// Config file was found but another error was produced
}
}

// Config file found and successfully parsed
Expand Down
93 changes: 93 additions & 0 deletions errors.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,93 @@
package viper

import (
"fmt"
)

// FileLookupError is returned when Viper cannot resolve a configuration file.
//
// This is meant to be a common interface for all file look-up errors, occurring either because a
// file does not exist or because it cannot find any file matching finder criteria.
type FileLookupError interface {
error

fileLookup()
}

// ConfigFileNotFoundError denotes failing to find a configuration file from a search.
//
// Deprecated: This is error wraps [FileNotFoundFromSearchError], which should be used instead.
type ConfigFileNotFoundError struct {
locations []string
name string
}

// Error returns the formatted error.
func (e ConfigFileNotFoundError) Error() string {
return e.Unwrap().Error()
}

// Unwraps to FileNotFoundFromSearchError.
func (e ConfigFileNotFoundError) Unwrap() error {
return FileNotFoundFromSearchError(e)
}

// FileNotFoundFromSearchError denotes failing to find a configuration file from a search.
// Wraps ConfigFileNotFoundError.
type FileNotFoundFromSearchError struct {
locations []string
name string
}

func (e FileNotFoundFromSearchError) fileLookup() {}

// Error returns the formatted error.
func (e FileNotFoundFromSearchError) Error() string {
message := fmt.Sprintf("File %q not found", e.name)

if len(e.locations) > 0 {
message += fmt.Sprintf(" in %v", e.locations)
}

return message
}

// FileNotFoundError denotes failing to find a specific configuration file.
type FileNotFoundError struct {
err error
path string
}

func (e FileNotFoundError) fileLookup() {}

// Error returns the formatted error.
func (e FileNotFoundError) Error() string {
return fmt.Sprintf("file not found: %s", e.path)
}

// ConfigFileAlreadyExistsError denotes failure to write new configuration file.
type ConfigFileAlreadyExistsError string

// Error returns the formatted error when configuration already exists.
func (e ConfigFileAlreadyExistsError) Error() string {
return fmt.Sprintf("Config File %q Already Exists", string(e))
}

// ConfigMarshalError happens when failing to marshal the configuration.
type ConfigMarshalError struct {
err error
}

// Error returns the formatted configuration error.
func (e ConfigMarshalError) Error() string {
return fmt.Sprintf("While marshaling config: %s", e.err.Error())
}

// UnsupportedConfigError denotes encountering an unsupported
// configuration filetype.
type UnsupportedConfigError string

// Error returns the formatted configuration error.
func (str UnsupportedConfigError) Error() string {
return fmt.Sprintf("Unsupported Config Type %q", string(str))
}
5 changes: 2 additions & 3 deletions file.go
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
package viper

import (
"fmt"
"os"
"path/filepath"

Expand Down Expand Up @@ -50,7 +49,7 @@ func (v *Viper) findConfigFileWithFinder(finder Finder) (string, error) {
}

if len(results) == 0 {
return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
return "", ConfigFileNotFoundError{name: v.configName, locations: v.configPaths}
}

// We call clean on the final result to ensure that the path is in its canonical form.
Expand All @@ -69,7 +68,7 @@ func (v *Viper) findConfigFileOld() (string, error) {
return file, nil
}
}
return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
return "", ConfigFileNotFoundError{name: v.configName, locations: v.configPaths}
}

func (v *Viper) searchInPath(in string) (filename string) {
Expand Down
45 changes: 7 additions & 38 deletions viper.go
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@ import (
"errors"
"fmt"
"io"
fs "io/fs"
"log/slog"
"os"
"path/filepath"
Expand All @@ -44,49 +45,12 @@ import (
"github.com/spf13/viper/internal/features"
)

// ConfigMarshalError happens when failing to marshal the configuration.
type ConfigMarshalError struct {
err error
}

// Error returns the formatted configuration error.
func (e ConfigMarshalError) Error() string {
return fmt.Sprintf("While marshaling config: %s", e.err.Error())
}

var v *Viper

func init() {
v = New()
}

// UnsupportedConfigError denotes encountering an unsupported
// configuration filetype.
type UnsupportedConfigError string

// Error returns the formatted configuration error.
func (str UnsupportedConfigError) Error() string {
return fmt.Sprintf("Unsupported Config Type %q", string(str))
}

// ConfigFileNotFoundError denotes failing to find configuration file.
type ConfigFileNotFoundError struct {
name, locations string
}

// Error returns the formatted configuration error.
func (fnfe ConfigFileNotFoundError) Error() string {
return fmt.Sprintf("Config File %q Not Found in %q", fnfe.name, fnfe.locations)
}

// ConfigFileAlreadyExistsError denotes failure to write new configuration file.
type ConfigFileAlreadyExistsError string

// Error returns the formatted error when configuration already exists.
func (faee ConfigFileAlreadyExistsError) Error() string {
return fmt.Sprintf("Config File %q Already Exists", string(faee))
}

// A DecoderConfigOption can be passed to viper.Unmarshal to configure
// mapstructure.DecoderConfig options.
type DecoderConfigOption func(*mapstructure.DecoderConfig)
Expand Down Expand Up @@ -1527,8 +1491,13 @@ func (v *Viper) ReadInConfig() error {
}

v.logger.Debug("reading file", "file", filename)

file, err := afero.ReadFile(v.fs, filename)
if err != nil {
if errors.Is(err, fs.ErrNotExist) {
// The specified config file is missing
return FileNotFoundError{err: err, path: filename}
} else if err != nil {
// We hit some other error from the filesystem that isn't a missing file
return err
}

Expand Down
40 changes: 37 additions & 3 deletions viper_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -359,7 +359,7 @@ func TestReadInConfig(t *testing.T) {
t.Run("config file set", func(t *testing.T) {
fs := afero.NewMemMapFs()

err := fs.Mkdir("/etc/viper", 0o777)
err := fs.Mkdir(testutil.AbsFilePath(t, "/etc/viper"), 0o777)
require.NoError(t, err)

file, err := fs.Create(testutil.AbsFilePath(t, "/etc/viper/config.yaml"))
Expand Down Expand Up @@ -1573,6 +1573,28 @@ func TestReadConfigWithSetConfigFile(t *testing.T) {
assert.Equal(t, 45000, v.GetInt("hello.pop"))
}

func TestWrongFileNotFound(t *testing.T) {
_, config := initDirs(t)

v := New()
v.SetConfigName(config)
v.SetDefault(`key`, `default`)

v.SetConfigFile(`whatareyoutalkingabout.yaml`)

err := v.ReadInConfig()

var fileLookupError FileLookupError

// It matches all error types and the shared error interface.
assert.ErrorAs(t, err, &FileNotFoundError{})
assert.ErrorAs(t, err, &fileLookupError)

// Even though config did not load and the error might have
// been ignored by the client, the default still loads
assert.Equal(t, `default`, v.GetString(`key`))
}

func TestIsSet(t *testing.T) {
v := New()
v.SetConfigType("yaml")
Expand Down Expand Up @@ -1652,7 +1674,13 @@ func TestWrongDirsSearchNotFound(t *testing.T) {
v.AddConfigPath(`thispathaintthere`)

err := v.ReadInConfig()
assert.IsType(t, ConfigFileNotFoundError{"", ""}, err)

var fileLookupError FileLookupError

// It matches all error types and the shared error interface.
assert.ErrorAs(t, err, &ConfigFileNotFoundError{})
assert.ErrorAs(t, err, &FileNotFoundFromSearchError{})
assert.ErrorAs(t, err, &fileLookupError)

// Even though config did not load and the error might have
// been ignored by the client, the default still loads
Expand All @@ -1670,7 +1698,13 @@ func TestWrongDirsSearchNotFoundForMerge(t *testing.T) {
v.AddConfigPath(`thispathaintthere`)

err := v.MergeInConfig()
assert.Equal(t, reflect.TypeOf(ConfigFileNotFoundError{"", ""}), reflect.TypeOf(err))

var fileLookupError FileLookupError

// It matches both types of errors.
assert.ErrorAs(t, err, &ConfigFileNotFoundError{})
assert.ErrorAs(t, err, &FileNotFoundFromSearchError{})
assert.ErrorAs(t, err, &fileLookupError)

// Even though config did not load and the error might have
// been ignored by the client, the default still loads
Expand Down
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