[TOML ConfigSource] add support for executing fallback CLI commands

Signed-off-by: Tariq Ibrahim <[email protected]>

Author: tariq1890

pkg/config/engine/containerd/containerd.go

@@ -129,7 +129,11 @@ func (c *Config) GetRuntimeConfig(name string) (engine.RuntimeConfig, error) {
 // CommandLineSource returns the CLI-based containerd config loader
 func CommandLineSource(hostRoot string) toml.Loader {
 	commandLine := chrootIfRequired(hostRoot, "containerd", "config", "dump")
-	return toml.FromCommandLine(commandLine[0], commandLine[1:]...)
+
+	var cliCommands []toml.CLICommand
+	cliCommands = append(cliCommands, toml.NewCLICommand(commandLine[0], commandLine[1:]))
+
+	return toml.FromCommandLine(cliCommands)
 }
 
 func chrootIfRequired(hostRoot string, commandLine ...string) []string {

pkg/config/engine/crio/crio.go

@@ -155,8 +155,14 @@ func (c *Config) GetRuntimeConfig(name string) (engine.RuntimeConfig, error) {
 
 // CommandLineSource returns the CLI-based crio config loader
 func CommandLineSource(hostRoot string) toml.Loader {
-	commandLine := chrootIfRequired(hostRoot, "crio", "status", "config")
-	return toml.FromCommandLine(commandLine[0], commandLine[1:]...)
+	crioCommandLine := chrootIfRequired(hostRoot, "crio", "status", "config")
+	crioCommandLineFallback := chrootIfRequired(hostRoot, "crio-status", "config")
+
+	var cliCommands []toml.CLICommand
+	cliCommands = append(cliCommands, toml.NewCLICommand(crioCommandLine[0], crioCommandLine[1:]))
+	cliCommands = append(cliCommands, toml.NewCLICommand(crioCommandLineFallback[0], crioCommandLineFallback[1:]))
+
+	return toml.FromCommandLine(cliCommands)
 }
 
 func chrootIfRequired(hostRoot string, commandLine ...string) []string {

pkg/config/toml/source-cli.go

@@ -18,18 +18,35 @@ package toml
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"os/exec"
 )
 
+type CLICommand struct {
+	cmd  string
+	args []string
+}
+
 type tomlCliSource struct {
-	command string
-	args    []string
+	cliCommands []CLICommand
 }
 
 func (c tomlCliSource) Load() (*Tree, error) {
+	var errs error
+	for _, clicmd := range c.cliCommands {
+		out, err := executeCommand(clicmd.cmd, clicmd.args)
+		if err == nil {
+			return LoadBytes(out)
+		}
+		errs = errors.Join(err)
+	}
+	return nil, errs
+}
+
+func executeCommand(command string, args []string) ([]byte, error) {
 	//nolint:gosec  // Subprocess launched with a potential tainted input or cmd arguments
-	cmd := exec.Command(c.command, c.args...)
+	cmd := exec.Command(command, args...)
 
 	var outb bytes.Buffer
 	var errb bytes.Buffer
@@ -38,8 +55,15 @@ func (c tomlCliSource) Load() (*Tree, error) {
 	cmd.Stderr = &errb
 	if err := cmd.Run(); err != nil {
 		// TODO: Log to stderr in case of failure
-		return nil, fmt.Errorf("failed to run command %v %v: %w", c.command, c.args, err)
+		return nil, fmt.Errorf("failed to run command %v %v: %w", command, args, err)
 	}
 
-	return LoadBytes(outb.Bytes())
+	return outb.Bytes(), nil
+}
+
+func NewCLICommand(command string, args []string) CLICommand {
+	return CLICommand{
+		cmd:  command,
+		args: args,
+	}
 }

pkg/config/toml/source.go

@@ -35,13 +35,14 @@ func FromFile(path string) Loader {
 }
 
 // FromCommandLine creates a TOML source from the output of a shell command and its corresponding args.
-// If the command is empty, an empty config is returned.
-func FromCommandLine(cmd string, args ...string) Loader {
-	if len(cmd) == 0 {
+// It accepts multiple commands as input, executing commands and returning on the first sccessful output
+// or falling back to the next command in the input slice. If the command slice is empty,
+// an empty config is returned.
+func FromCommandLine(cliCmds []CLICommand) Loader {
+	if len(cliCmds) == 0 {
 		return Empty
 	}
 	return &tomlCliSource{
-		command: cmd,
-		args:    args,
+		cliCommands: cliCmds,
 	}
 }