Install a precompiled module from the latest Github release. (#198)

Checks Nginx version, architecture, and operating system.
Downloads the file into a temp directory, then moves it to nginx's
modules directory and creates a symbolic link.

---------

Co-authored-by: Jed Liu <[email protected]>

cmd/internal/nginx/nginx.go

@@ -1,13 +1,12 @@
 package nginx
 
 import (
-	"fmt"
-
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
 
 	"github.com/akitasoftware/akita-cli/cmd/internal/pluginloader"
 	"github.com/akitasoftware/akita-cli/integrations/nginx"
+	"github.com/akitasoftware/akita-cli/printer"
 	"github.com/akitasoftware/akita-cli/rest"
 	"github.com/akitasoftware/akita-cli/telemetry"
 )
@@ -19,16 +18,21 @@ var (
 	// Port number that the module will send traffic to
 	listenPortFlag uint16
 
-	// Dedvelopment mode -- dump out traffic locally
+	// Development mode -- dump out traffic locally
 	developmentFlag bool
+
+	// Dry run for install -- find version but do not install
+	dryRunFlag bool
+
+	// Module destination
+	moduleDestFlag string
 )
 
 var Cmd = &cobra.Command{
 	Use:          "nginx",
 	Short:        "Install or use Akita's NGINX module to collect API traffic.",
 	SilenceUsage: true,
-	// TODO: un-hide when ready for use
-	Hidden: true,
+	Hidden:       false,
 }
 
 var CaptureCmd = &cobra.Command{
@@ -40,21 +44,23 @@ var CaptureCmd = &cobra.Command{
 }
 
 var InstallCmd = &cobra.Command{
-	// TODO: substitute in the real name
-	Use:          "xinstall",
+	Use:          "install",
 	Short:        "Download a precompiled NGINX module.",
 	Long:         "Download a precompiled version of akita-nginx-module that matches the currently installed version of NGINX.",
 	SilenceUsage: true,
 	RunE:         installNginxModule,
 }
 
 func init() {
-	Cmd.PersistentFlags().StringVar(&projectFlag, "project", "", "Your Akita project.")
-	Cmd.PersistentFlags().Uint16Var(&listenPortFlag, "port", 50080, "The port number on which to listen for connections.")
-	Cmd.PersistentFlags().BoolVar(&developmentFlag, "dev", false, "Enable development mode; only dumps traffic.")
-	Cmd.PersistentFlags().MarkHidden("dev")
+	CaptureCmd.PersistentFlags().StringVar(&projectFlag, "project", "", "Your Akita project.")
+	CaptureCmd.PersistentFlags().Uint16Var(&listenPortFlag, "port", 50080, "The port number on which to listen for connections.")
+	CaptureCmd.PersistentFlags().BoolVar(&developmentFlag, "dev", false, "Enable development mode; only dumps traffic.")
+	CaptureCmd.PersistentFlags().MarkHidden("dev")
 
 	Cmd.AddCommand(CaptureCmd)
+
+	InstallCmd.PersistentFlags().BoolVar(&dryRunFlag, "dry-run", false, "Determine NGINX version but do not download or install the module.")
+	InstallCmd.PersistentFlags().StringVar(&moduleDestFlag, "dest", "", "Specify the directory into which to install the module.")
 	Cmd.AddCommand(InstallCmd)
 }
 
@@ -90,5 +96,24 @@ func captureNginxTraffic(cmd *cobra.Command, args []string) error {
 }
 
 func installNginxModule(cmd *cobra.Command, args []string) error {
-	return fmt.Errorf("This command is not yet implemented.")
+	err := nginx.InstallModule(&nginx.InstallArgs{
+		DryRun: dryRunFlag,
+	})
+	if err != nil {
+		var installError *nginx.InstallationError
+		switch {
+		case errors.As(err, &installError):
+			// Log the error, then what the user should do next
+			printer.Errorf("%v\n", err)
+			printer.Infof("%v\n", installError.Remedy)
+		default:
+			printer.Errorf("Could not determine which NGINX platform and version to support: %v\n", err)
+			printer.Infof("Please contact [email protected] for assistance, or follow the instructions at https://github.com/akitasoftware/akita-nginx-module to install the module by hand.\n")
+		}
+
+		// Report the error here because we don't report it to the root command
+		telemetry.Error("command execution", err)
+
+	}
+	return nil
 }

integrations/nginx/github.go

@@ -0,0 +1,88 @@
+package nginx
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+
+	"github.com/akitasoftware/akita-cli/printer"
+)
+
+// The Github API asset type, with most fields missing
+type GithubAsset struct {
+	Name string `json:"name"`
+	ID   int    `json:"id"`
+}
+
+// The Github API release type, with most fields missing
+type GithubRelease struct {
+	TagName string        `json:"tag_name"`
+	Assets  []GithubAsset `json:"assets"`
+}
+
+// Return a list of all the assets available in the latest release
+func GetLatestReleaseAssets() ([]GithubAsset, error) {
+	response, err := http.Get("https://api.github.com/repos/akitasoftware/akita-nginx-module/releases/latest")
+	if err != nil {
+		printer.Debugf("Error performing GET request: %v", err)
+		return nil, err
+	}
+	defer response.Body.Close()
+
+	printer.Debugf("Status: %q\n", response.Status)
+	if response.StatusCode != 200 {
+		return nil, fmt.Errorf("Response code %d from Github", response.StatusCode)
+	}
+
+	decoder := json.NewDecoder(response.Body)
+	var release GithubRelease
+	err = decoder.Decode(&release)
+	if err != nil {
+		printer.Debugf("JSON decode error: %v\n", err)
+		return nil, err
+	}
+
+	return release.Assets, nil
+}
+
+// Download a specific asset (the prebuilt module) to a temporary file
+func DownloadReleaseAsset(id int, filename string) error {
+	download, err := os.Create(filename)
+	if err != nil {
+		printer.Errorf("Can't create destination file: %v\n", err)
+		return err
+	}
+	defer download.Close()
+
+	// Need to set a header to get the binary rather than JSON
+	client := &http.Client{}
+	url := fmt.Sprintf("https://api.github.com/repos/akitasoftware/akita-nginx-module/releases/assets/%d", id)
+	req, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		printer.Errorf("Failed to create download request: %v\n", err)
+		return err
+	}
+
+	req.Header.Add("Accept", "application/octet-stream")
+	response, err := client.Do(req)
+	if err != nil {
+		printer.Errorf("HTTP download failure: %v\n", err)
+		return err
+	}
+	defer response.Body.Close()
+
+	if response.StatusCode != 200 {
+		printer.Errorf("Module download has status %q\n", response.Status)
+		return fmt.Errorf("Response code %d from Github", response.StatusCode)
+	}
+
+	_, err = io.Copy(download, response.Body)
+	if err != nil {
+		printer.Errorf("HTTP download failure: %v\n", err)
+		return err
+	}
+
+	return nil
+}