improving error messages, updating .gitignore and README

.gitignore

@@ -1,2 +1,3 @@
-otel-plugin
-otel
+otel
+*.json
+*.tar.gz

README.md

@@ -6,6 +6,12 @@ This is a plugin that makes it easy to use OTel with Spin.
 
 Spin applications have the ability to export metrics and trace data. This plugin provides dashboards for viewing the data.
 
+## Requirements
+
+This plugin relies on third-party software to work properly. Please be sure you have the following installed before continuing:
+
+- Latest version of [Docker](https://www.docker.com/products/docker-desktop)
+
 # Installation
 
 The trigger is installed as a Spin plugin. It can be installed from a release or build.
@@ -34,7 +40,7 @@ Alternatively, use the `spin pluginify` plugin to install from a fresh build. Th
 ```sh
 spin plugins install pluginify
 go build -o otel
-spin pluginify install
+spin pluginify --install
 ```
 
 # Usage

cmd/cleanup.go

@@ -37,6 +37,10 @@ func getIDs(dockerOutput []byte) []string {
 }
 
 func cleanUp() error {
+	if err := checkDocker(); err != nil {
+		return err
+	}
+
 	fmt.Println("Stopping Spin OTel Docker containers...")
 
 	getContainers := exec.Command("docker", "ps")

cmd/root.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"fmt"
 	"os"
+	"os/exec"
 	"path"
 
 	open "github.com/fermyon/otel-plugin/cmd/open"
@@ -28,20 +29,34 @@ func setOtelConfigPath() error {
 	otelConfigPath = path.Join(path.Dir(executablePath), otelConfigDirName)
 
 	if _, err := os.Stat(otelConfigPath); os.IsNotExist(err) {
-		return fmt.Errorf("the directory in which the plugin binary is executed is missing necessary files, so please make sure the plugin was installed using \"spin plugins install otel\"")
+		return fmt.Errorf("The directory in which the plugin binary is executed is missing necessary files, so please make sure the plugin was installed using \"spin plugins install otel\"")
+	}
+
+	return nil
+}
+
+// checkDocker checks whether Docker is installed and the Docker daemon is running
+func checkDocker() error {
+	cmd := exec.Command("docker", "--version")
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("Docker appears not to be installed, so please visit their install page and try again once installed: https://www.docker.com/products/docker-desktop")
+	}
+
+	cmd = exec.Command("docker", "info")
+	if err := cmd.Run(); err != nil {
+		return fmt.Errorf("The Docker daemon appears not to be running. The command to start Docker depends on your operating system. For instructions, check the correct page under https://docs.docker.com/engine/install")
 	}
 
 	return nil
 }
 
 func Execute() {
 	if err := setOtelConfigPath(); err != nil {
-		fmt.Fprintln(os.Stderr, fmt.Errorf("error finding the otel-config directory: %w", err))
+		fmt.Fprintln(os.Stderr, fmt.Errorf("Error finding the \"otel-config\" directory: %w", err))
 		os.Exit(1)
 	}
 
 	if err := rootCmd.Execute(); err != nil {
-		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
 }

cmd/setup.go

@@ -21,9 +21,13 @@ var setUpCmd = &cobra.Command{
 }
 
 func setUp() error {
+	if err := checkDocker(); err != nil {
+		return err
+	}
+
 	composeFile := path.Join(otelConfigPath, "compose.yaml")
 	if _, err := os.Stat(composeFile); os.IsNotExist(err) {
-		return fmt.Errorf("the otel-config directory is missing the \"compose.yaml\" file, so please consider removing and re-installing the otel plugin")
+		return fmt.Errorf("The \"otel-config\" directory is missing the \"compose.yaml\" file, so please consider removing and re-installing the otel plugin")
 	}
 
 	cmd := exec.Command("docker", "compose", "-f", composeFile, "up", "-d")
@@ -36,6 +40,6 @@ func setUp() error {
 		return err
 	}
 
-	fmt.Println("The Spin OTel resources are now running. Be sure to run the `spin otel cleanup` command when you are finished using them.")
+	fmt.Println("The Spin OTel resources are now running. Be sure to run the \"spin otel cleanup\" command when you are finished using them.")
 	return nil
 }

cmd/up.go

@@ -11,7 +11,7 @@ import (
 var upCmd = &cobra.Command{
 	Use:   "up",
 	Short: "Runs a Spin App with the default OTel environment variables.",
-	Long:  "Runs a Spin App with the default OTel environment variables. Any flags that work with the `spin up` command, will work with the `spin otel up` command: 'spin otel up -- --help'",
+	Long:  "Runs a Spin App with the default OTel environment variables. Any flags that work with the \"spin up\" command, will work with the \"spin otel up\" command: \"spin otel up -- --help\"",
 	RunE: func(cmd *cobra.Command, args []string) error {
 		if err := up(args); err != nil {
 			return err
@@ -22,9 +22,13 @@ var upCmd = &cobra.Command{
 }
 
 func up(args []string) error {
+	if err := checkDocker(); err != nil {
+		return err
+	}
+
 	pathToSpin := os.Getenv("SPIN_BIN_PATH")
 	if pathToSpin == "" {
-		return fmt.Errorf("please ensure that you are running 'spin otel up', rather than calling the OTel plugin binary directly")
+		return fmt.Errorf("Please ensure that you are running \"spin otel up\", rather than calling the OTel plugin binary directly")
 	}
 
 	// Passing flags and args after the '--'

main.go

@@ -1,32 +1,9 @@
 package main
 
 import (
-	"fmt"
-	"os"
-	"os/exec"
-
 	"github.com/fermyon/otel-plugin/cmd"
 )
 
 func main() {
-	if err := checkDependencies(); err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
-	}
-
 	cmd.Execute()
 }
-
-func checkDependencies() error {
-	cmd := exec.Command("docker", "--version")
-	if err := cmd.Run(); err != nil {
-		return fmt.Errorf("docker appears not to be installed, so please visit their install page and try again once installed: https://www.docker.com/products/docker-desktop/")
-	}
-
-	cmd = exec.Command("docker", "info")
-	if err := cmd.Run(); err != nil {
-		return fmt.Errorf("the docker daemon appears not to be running, so please start the daemon and try again")
-	}
-
-	return nil
-}