feature(fxconfig): add config file support (#57)

#### Type of change

- New feature
- Test update
- Documentation update
- Breaking change

#### Description

This PR introduces config file support to fxconfig as described in #58. 
Note that this PR does not yet introduce MSP-based policies nor the
multi-org endorsement flows. These features will come in the next PRs.

#### Additional details (Optional)

See readme in `tools/fxconfig/docs/README.md

#### Related issues

- #55
- Resolves #58

Signed-off-by: Marcus Brandenburger <bur@zurich.ibm.com>

Author: mbrandenburger

go.mod

@@ -22,10 +22,12 @@ require (
 	github.com/hyperledger/fabric-x-committer v0.1.8
 	github.com/hyperledger/fabric-x-common v0.1.0
 	github.com/spf13/cobra v1.10.2
+	github.com/spf13/viper v1.21.0
 	github.com/stretchr/testify v1.11.1
 	github.com/testcontainers/testcontainers-go v0.40.0
 	golang.org/x/text v0.33.0
 	google.golang.org/protobuf v1.36.11
+	gopkg.in/yaml.v3 v3.0.1
 )
 
 require (
@@ -122,7 +124,6 @@ require (
 	github.com/spf13/afero v1.15.0 // indirect
 	github.com/spf13/cast v1.10.0 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
-	github.com/spf13/viper v1.21.0 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/sykesm/zap-logfmt v0.0.4 // indirect
 	github.com/tklauser/go-sysconf v0.3.12 // indirect
@@ -150,5 +151,4 @@ require (
 	google.golang.org/genproto/googleapis/api v0.0.0-20260120221211-b8f7ae30c516 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20260120174246-409b4a993575 // indirect
 	google.golang.org/grpc v1.78.0 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

tools/fxconfig/cmd/cmd.go

@@ -0,0 +1,31 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+// Package cmd implements the command-line interface for fxconfig.
+// It provides commands for namespace management and configuration handling.
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+
+	"github.com/hyperledger/fabric-x/tools/fxconfig/internal/config"
+)
+
+// configKeyType is a custom type for context keys to avoid collisions.
+type configKeyType string
+
+// configKey is the context key used to store and retrieve configuration.
+const configKey configKeyType = "app-config"
+
+// getConfig retrieves the configuration from the command context.
+// Panics if the configuration is not found, indicating a programming error.
+func getConfig(cmd *cobra.Command) *config.Config {
+	cfg, ok := cmd.Context().Value(configKey).(*config.Config)
+	if !ok {
+		panic("programming error: extracting config from context failed")
+	}
+	return cfg
+}

tools/fxconfig/cmd/config.go

@@ -0,0 +1,36 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+	"gopkg.in/yaml.v3"
+)
+
+// NewInfoCommand returns a command that displays the effective configuration.
+// The configuration is shown as YAML after applying all overrides from
+// flags, environment variables, and config files.
+func NewInfoCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "info",
+		Short: "Display system-wide information",
+		Long:  ``,
+		RunE: func(cmd *cobra.Command, _ []string) error {
+			cfg := getConfig(cmd)
+
+			out, err := yaml.Marshal(cfg)
+			if err != nil {
+				return err
+			}
+
+			cmd.Println(string(out))
+			return nil
+		},
+	}
+
+	return cmd
+}

tools/fxconfig/cmd/info.go

@@ -0,0 +1,32 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package cmd
+
+import (
+	"github.com/spf13/cobra"
+
+	"github.com/hyperledger/fabric-x/tools/fxconfig/internal/namespace"
+)
+
+// NewNamespaceCommand returns the namespace command group.
+// This command provides subcommands for namespace lifecycle operations:
+// create, update, and list.
+func NewNamespaceCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "namespace",
+		Short: "Perform namespace operations",
+		Long:  "",
+	}
+
+	cmd.AddCommand(
+		newCreateCommand(namespace.DeployNamespace),
+		newListCommand(namespace.ListNamespaces),
+		newUpdateCommand(namespace.DeployNamespace),
+	)
+
+	return cmd
+}