fix: Refresh ~/.finch/confg.json based on finch.yaml

Suppose we have configured the `creds_helpers` in `~/.finch/finch.yaml` as
follows, and subsequently initialized a VM (`finch vm init`).

```
cpus: 6
creds_helpers:
    - ecr-login
memory: 8GiB
vmType: vz
rosetta: true
```

As a result, `~/.finch/config.json` is created, and it contains the
following:

```
{"credsStore":"ecr-login"}
```

This allows us to utilize the Amazon ECR Docker Credential Helper within Finch.

Subsequently, suppose we stop and remove the VM
(`finch vm stop` && `finch vm remove`), and then remove the
`creds_helpers` configuration from `finch.yaml`.

We then configure the `finch.yaml` file as follows:

```
cpus: 6
memory: 8GiB
vmType: vz
rosetta: true
```

As a result, when we reinitialize the VM (`finch vm init`), the expected
behavior is that it will no longer use the Amazon ECR Docker Credential Helper.

However, when initializing the VM, despite the absence of `creds_helpers`
configuration in `finch.yaml`, the `"credsStore": "ecr-login"` remains in
`config.json`, allowing the continued use of the Amazon ECR Docker
Credential Helper.

This behavior has been reported in the following issue:

- runfinch#480

Furthermore, this issue occurs when we stop the VM (`finch vm stop`),
modify `finch.yaml`, and subsequently start the VM (`finch vm start`).

Consequently, we will modify the behavior to update `config.json` in
accordance with the `creds_helpers` configuration in `finch.yaml` when
initiating or starting the VM.

Note that in this pull request, the commits are divided as follows:

- Implement the logic to update `config.json` according to `finch.yaml`
  and change the function name (loadFinchConfig) in the config package
- Modify to call the logic to update `config.json` according to
  `finch.yaml` on the VM side
- Add unit tests for the credhelper package and modify unit tests for the
  config package
- Modify and add Behavior-Driven Development (BDD) Tests using Ginkgo on
  the VM side
- Add e2e tests

On the other hand, in this commit, the logic to update `config.json`
according to `finch.yaml` is implemented and the function name
(loadFinchConfig) is changed in the config package.

Signed-off-by: Hayato Kiwata <haytok@amazon.co.jp>

pkg/config/config.go

@@ -177,8 +177,8 @@ func Load(
 	return defCfg, nil
 }
 
-// loadFinchConfig Load Finch's configuration from a YAML file.
-func loadFinchConfig(fs afero.Fs, finchConfigPath string, logger flog.Logger, systemDeps LoadSystemDeps, mem fmemory.Memory) (*Finch, error) {
+// LoadFinchConfig Load Finch's configuration from a YAML file.
+func LoadFinchConfig(fs afero.Fs, finchConfigPath string, logger flog.Logger, systemDeps LoadSystemDeps, mem fmemory.Memory) (*Finch, error) {
 	b, err := afero.ReadFile(fs, finchConfigPath)
 	if err != nil {
 		return nil, fmt.Errorf("failed to read config file: %w", err)
@@ -202,7 +202,7 @@ func ModifyFinchConfig(fs afero.Fs, logger flog.Logger, finchConfigPath string,
 	systemDeps := system.NewStdLib()
 	mem := fmemory.NewMemory()
 
-	finchCfg, err := loadFinchConfig(fs, finchConfigPath, logger, systemDeps, mem)
+	finchCfg, err := LoadFinchConfig(fs, finchConfigPath, logger, systemDeps, mem)
 	if err != nil {
 		return isConfigUpdated, err
 	}

pkg/dependency/credhelper/cred_helper.go

@@ -5,16 +5,23 @@
 package credhelper
 
 import (
+	"encoding/json"
 	"fmt"
+	"os"
 	"path/filepath"
+	"slices"
 
+	"github.com/docker/cli/cli/config/configfile"
+	"github.com/docker/cli/cli/config/types"
 	"github.com/spf13/afero"
 
 	"github.com/runfinch/finch/pkg/command"
 	"github.com/runfinch/finch/pkg/config"
 	"github.com/runfinch/finch/pkg/dependency"
 	"github.com/runfinch/finch/pkg/flog"
+	"github.com/runfinch/finch/pkg/fmemory"
 	"github.com/runfinch/finch/pkg/path"
+	"github.com/runfinch/finch/pkg/system"
 )
 
 const (
@@ -96,3 +103,64 @@ func newDeps(
 
 	return deps
 }
+
+// RefreshConfigFile refreshes config.json according to finch.yaml.
+func RefreshConfigFile(fs afero.Fs, logger flog.Logger, finchConfigPath, configJSONPath string) error {
+	systemDeps := system.NewStdLib()
+	mem := fmemory.NewMemory()
+
+	finchCfg, err := config.LoadFinchConfig(fs, finchConfigPath, logger, systemDeps, mem)
+	if err != nil {
+		return err
+	}
+	if slices.Contains(finchCfg.CredsHelpers, "ecr-login") {
+		return nil
+	}
+
+	fileExists, err := afero.Exists(fs, configJSONPath)
+	if err != nil {
+		return err
+	}
+	if !fileExists {
+		return nil
+	}
+
+	fileRead, err := fs.Open(configJSONPath)
+	if err != nil {
+		return err
+	}
+	defer fileRead.Close() //nolint:errcheck // closing the file
+
+	var cfg configfile.ConfigFile
+
+	bytes, _ := afero.ReadAll(fileRead)
+	err = json.Unmarshal(bytes, &cfg)
+	if err != nil {
+		return err
+	}
+	if cfg.CredentialsStore == "" {
+		return nil
+	}
+
+	cfg.CredentialsStore = ""
+	if cfg.AuthConfigs == nil {
+		cfg.AuthConfigs = map[string]types.AuthConfig{}
+	}
+
+	finalCfgBytes, err := json.Marshal(&cfg)
+	if err != nil {
+		return err
+	}
+
+	file, err := fs.OpenFile(configJSONPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o600)
+	if err != nil {
+		return err
+	}
+	_, err = file.Write(finalCfgBytes)
+	if err != nil {
+		return err
+	}
+	defer file.Close() //nolint:errcheck // closing the file
+
+	return nil
+}