Update and add comments.

go/instances.go

@@ -0,0 +1,358 @@
+// This script runs a Terminal User Interface displaying a list of 
+// EC2 Instances located in an AWS account. A valid set of AWS 
+// credentials must be stored in ~/.aws/credentials before usage.
+// After running, press 'h' to view the help menu.
+// 
+// Dependencies:
+// 		go mod init aws-helpers
+// 		go get .
+// 
+// Use:
+// 		go run instances.go --profile default --region us-east-1
+// 
+// Build:
+// 		go build instances.go
+// 		./instances -p default -r us-east-1
+
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"strings"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/aws/session"
+	"github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/rivo/tview"
+	"github.com/gdamore/tcell/v2"
+)
+
+var (
+	profile 			string
+	region  			string
+	currentInstances 	[]*ec2.Instance
+	app              	= tview.NewApplication()
+	flex             	*tview.Flex
+)
+
+// Helper function to get the Name tag for an EC2 instance.
+func getInstanceName(instance *ec2.Instance) string {
+    for _, tag := range instance.Tags {
+        if aws.StringValue(tag.Key) == "Name" && tag.Value != nil && *tag.Value != "" {
+            return *tag.Value
+        }
+    }
+    return *instance.InstanceId // default to instance ID if no Name tag found
+}
+
+// Helper function to filter the displayed instances by filtered state.
+func fetchAndDisplayInstances(state string, svc *ec2.EC2, list *tview.List, detailsTable *tview.Table) {
+    var filterName string
+    switch state {
+    case "running":
+        filterName = "running"
+    case "stopped":
+        filterName = "stopped"
+    case "terminated":
+        filterName = "terminated"
+    default:
+        filterName = "any"
+    }
+
+    params := &ec2.DescribeInstancesInput{}
+    if filterName != "any" {
+        params.Filters = []*ec2.Filter{
+            {
+                Name:   aws.String("instance-state-name"),
+                Values: []*string{aws.String(filterName)},
+            },
+        }
+    }
+
+    resp, err := svc.DescribeInstances(params)
+    if err != nil {
+        log.Fatalf("Failed to retrieve EC2 instances: %s", err)
+    }
+
+    list.Clear()
+	currentInstances = nil
+    for _, res := range resp.Reservations {
+        for _, instance := range res.Instances {
+            currentInstances = append(currentInstances, instance)
+            list.AddItem(getInstanceName(instance), "", 0, nil)
+        }
+    }
+
+    if len(currentInstances) > 0 {
+        displayInstanceDetails(detailsTable, currentInstances[0])
+    }
+}
+
+// Helper function to display the instance details of the first instance in the list. Function executes when application first loads.
+func initialDisplay(svc *ec2.EC2, list *tview.List, detailsTable *tview.Table) {
+    fetchAndDisplayInstances("running", svc, list, detailsTable)
+}
+
+// Helper function to display the instance details.
+func displayInstanceDetails(table *tview.Table, instance *ec2.Instance) {
+	table.Clear()
+
+	// Headers
+	headers := []string{
+		"Field", "Value",
+	}
+
+	// Assign headers to table.
+	for col, header := range headers {
+		cell := tview.NewTableCell(header).
+			SetTextColor(tview.Styles.SecondaryTextColor).
+			SetAlign(tview.AlignCenter).
+			SetAttributes(tcell.AttrBold)
+		table.SetCell(0, col, cell)
+	}
+
+	// Ordered list of fields
+	fields := []string{
+		"State",
+		"Instance ID",
+		"Type",
+		"AMI ID",
+		"Architecture",
+		"Public DNS Name",
+		"Public IP Address",
+		"PrivateDnsName",
+		"PrivateIpAddress",
+		"Pem Key Name",
+		"VPC ID",
+		"Subnet ID",
+	}
+
+	// Mapping of fields to their pointers
+	fieldMap := map[string]**string{
+		"State":             &instance.State.Name,
+		"Instance ID":       &instance.InstanceId,
+		"Type":              &instance.InstanceType,
+		"AMI ID":            &instance.ImageId,
+		"Architecture":      &instance.Architecture,
+		"Public DNS Name":   &instance.PublicDnsName,
+		"Public IP Address": &instance.PublicIpAddress,
+		"PrivateDnsName":    &instance.PrivateDnsName,
+		"PrivateIpAddress":  &instance.PrivateIpAddress,
+		"Pem Key Name":      &instance.KeyName,
+		"VPC ID":            &instance.VpcId,
+		"Subnet ID":         &instance.SubnetId,
+	}
+
+	// Add instance details to table.
+	row := 1
+	for _, field := range fields {
+		ptr := fieldMap[field]
+		value := "Unknown"
+		if *ptr != nil {
+			value = **ptr
+		}
+		table.SetCell(row, 0, tview.NewTableCell(field))
+		table.SetCell(row, 1, tview.NewTableCell(value))
+		row++
+	}
+
+	// Special cases that return non-string values.
+	table.SetCell(row, 0, tview.NewTableCell("Iam Instance Profile Arn"))
+	if instance.IamInstanceProfile != nil && instance.IamInstanceProfile.Arn != nil {
+		table.SetCell(row, 1, tview.NewTableCell(*instance.IamInstanceProfile.Arn))
+	} else {
+		table.SetCell(row, 1, tview.NewTableCell("No ARN"))
+	}
+	row++
+
+	table.SetCell(row, 0, tview.NewTableCell("Security Groups"))
+	if instance.SecurityGroups != nil {
+		var groupNames []string
+		for _, group := range instance.SecurityGroups {
+			if group != nil && group.GroupName != nil {
+				groupNames = append(groupNames, *group.GroupName)
+			}
+		}
+		table.SetCell(row, 1, tview.NewTableCell(strings.Join(groupNames, ", ")))
+	} else {
+		table.SetCell(row, 1, tview.NewTableCell("No Security Groups"))
+	}
+}
+
+// Helper function to start an instance.
+func startInstance(svc *ec2.EC2, instance *ec2.Instance) error {
+	input := &ec2.StartInstancesInput{
+		InstanceIds: []*string{
+			instance.InstanceId,
+		},
+	}
+	_, err := svc.StartInstances(input)
+	return err
+}
+
+// Helper function to stop an instance.
+func stopInstance(svc *ec2.EC2, instance *ec2.Instance) error {
+	input := &ec2.StopInstancesInput{
+		InstanceIds: []*string{
+			instance.InstanceId,
+		},
+	}
+	_, err := svc.StopInstances(input)
+	return err
+}
+
+// Helper function to reboot an instance.
+func rebootInstance(svc *ec2.EC2, instance *ec2.Instance) error {
+	input := &ec2.RebootInstancesInput{
+		InstanceIds: []*string{
+			instance.InstanceId,
+		},
+	}
+	_, err := svc.RebootInstances(input)
+	return err
+}
+
+// Helper function to create a confirm prompt before action is taken.
+func confirmModal(title, text string, confirmFunc func()) {
+	modal := tview.NewModal().
+		SetText(text).
+		AddButtons([]string{"Yes", "No"}).
+		SetDoneFunc(func(buttonIndex int, buttonLabel string) {
+			if buttonLabel == "Yes" {
+				confirmFunc()
+			}
+			app.SetRoot(flex, true)
+		})
+	fmt.Println("Attempting to confirm start instance")
+	app.SetRoot(modal, true)
+}
+
+// Helper function to display any AWS operation errors to the user.
+func handleEC2OperationResult(err error, successMsg string, list *tview.List, detailsTable *tview.Table) {
+	if err != nil {
+		// Show error modal
+		errorModal := tview.NewModal().
+			SetText("Error: " + err.Error()).
+			AddButtons([]string{"Close"}).
+			SetDoneFunc(func(buttonIndex int, buttonLabel string) {
+				app.SetRoot(flex, true)
+			})
+		app.SetRoot(errorModal, true)
+	} else {
+		// Refresh the current instance details
+		displayInstanceDetails(detailsTable, currentInstances[list.GetCurrentItem()])
+	}
+}
+
+func main() {
+	// Require profile and region from the user.
+	flag.StringVar(&profile, "profile", "", "AWS Profile")
+	flag.StringVar(&profile, "p", "", "AWS Profile (shorthand)")
+	flag.StringVar(&region, "region", "", "AWS Region")
+	flag.StringVar(&region, "r", "", "AWS Region (shorthand)")
+	flag.Parse()
+
+	if profile == "" || region == "" {
+		fmt.Println("Both --profile (-p) and --region (-r) are required.")
+		os.Exit(1)
+	}
+
+	// Establish AWS connection.
+	sess, err := session.NewSessionWithOptions(session.Options{
+		Profile: profile,
+		Config: aws.Config{
+			Region: aws.String(region),
+		},
+	})
+	if err != nil {
+		log.Fatalf("Failed to initialize AWS session: %s", err)
+	}
+
+	svc := ec2.New(sess)
+
+	// Create the application.
+	app = tview.NewApplication()
+	list := tview.NewList().ShowSecondaryText(false)
+	detailsTable := tview.NewTable().SetBorders(true)
+	list.SetBorder(true).SetTitle("Instances")
+	detailsTable.SetBorder(true).SetTitle("Instance Details")
+
+	initialDisplay(svc, list, detailsTable)
+
+	// Changed function to keep index and currentInstances slice in sync during user navigation.
+	list.SetChangedFunc(func(index int, mainText string, secondaryText string, shortcut rune) {
+		if index >= 0 && index < len(currentInstances) {
+			displayInstanceDetails(detailsTable, currentInstances[index]) 
+		}
+	})
+
+	// Global view and add instance information.
+	flex = tview.NewFlex().
+	AddItem(list, 0, 1, true).
+	AddItem(detailsTable, 0, 2, false)
+
+	// Create the help modal.
+	helpModal := tview.NewModal().
+	SetText("Keyboard Commands:\n\nh - Show this help menu\nq - Quit the program\nr - Display running instances\na - Display all instances\ns - Display stopped instances\nt - Display terminated instances\n'S'(Shift+S) - Start instance.\n'X'(Shift+X) - Stop instance.\n'R'(Shift+r) - Reboot instance.").
+		AddButtons([]string{"Close"}).
+		SetDoneFunc(func(buttonIndex int, buttonLabel string) {
+			if buttonLabel == "Close" {
+				app.SetRoot(flex, true)
+			}
+		})
+
+	// Assign keybindings.
+	app.SetRoot(flex, true).
+		SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+			switch event.Key() {
+			case tcell.KeyRune:
+				switch event.Rune() {
+				case 'h': // Display help modal.
+					app.SetRoot(helpModal, true)
+					return nil
+				case 'q': // Quit the application.
+					app.Stop()
+				case 'r': // Display running instances
+					fetchAndDisplayInstances("running", svc, list, detailsTable)
+					return nil
+				case 'a': // Display any(all) instances.
+					fetchAndDisplayInstances("any", svc, list, detailsTable)
+					return nil
+				case 's': // Display terminated instances.
+					fetchAndDisplayInstances("stopped", svc, list, detailsTable)
+					return nil
+				case 't': // Display terminated instances.
+					fetchAndDisplayInstances("terminated", svc, list, detailsTable)
+					return nil
+				case 'S': // Start Instance.
+					confirmModal("Start Instance", "Are you sure you want to start the instance?", func() {
+						fmt.Println("Executing start instance command")
+						err := startInstance(svc, currentInstances[list.GetCurrentItem()])
+						handleEC2OperationResult(err, "Successfully started the instance.", list, detailsTable)
+					})
+					return nil
+				case 'X': // Stop Instance.
+					confirmModal("Stop Instance", "Are you sure you want to stop the instance?", func() {
+						err := stopInstance(svc, currentInstances[list.GetCurrentItem()])
+						handleEC2OperationResult(err, "Successfully stopped the instance.", list, detailsTable)
+					})
+					return nil
+				case 'R': // Reboot Instance.
+					confirmModal("Reboot Instance", "Are you sure you want to reboot the instance?", func() {
+						err := rebootInstance(svc, currentInstances[list.GetCurrentItem()])
+						handleEC2OperationResult(err, "Successfully rebooted the instance.", list, detailsTable)
+					})
+				}
+			}
+			return event
+		})
+	
+	// Exit the application on panic.
+	if err := app.Run(); err != nil {
+		panic(err)
+	}
+}