Update canary test to use public S3 download link. (#404)

* Update canary test to use public S3 download link.

test/canary/canary_test.go

@@ -7,7 +7,9 @@ package canary
 import (
 	"errors"
 	"fmt"
+	"io"
 	"log"
+	"net/http"
 	"os"
 	"strings"
 	"testing"
@@ -22,6 +24,10 @@ import (
 
 const (
 	configInputPath = "resources/canary_config.json"
+	// todo: expand testing to include regional S3 links.
+	// todo: test ARM64, DEB, MSI based on OS type.
+	downloadLink = "https://amazoncloudwatch-agent.s3.amazonaws.com/amazon_linux/amd64/latest/amazon-cloudwatch-agent.rpm"
+	versionLink  = "https://amazoncloudwatch-agent.s3.amazonaws.com/info/latest/CWAGENT_VERSION"
 )
 
 func init() {
@@ -31,22 +37,24 @@ func init() {
 // TestCanary verifies downloading, installing, and starting the agent.
 // Reports metrics for each failure type.
 func TestCanary(t *testing.T) {
-	e := environment.GetEnvironmentMetaData()
-	defer setupCron(e.Bucket, e.S3Key)
+	defer setupCron()
 	// Don't care if uninstall fails. Agent might not be installed anyways.
 	_ = common.UninstallAgent(common.RPM)
 	// S3 keys always use backslash, so split on that to get filename.
-	installerFilePath := "./" + e.S3Key[strings.LastIndex(e.S3Key, "/")+1:]
-	err := awsservice.DownloadFile(e.Bucket, e.S3Key, installerFilePath)
+	installerFilePath := "./" + downloadLink[strings.LastIndex(downloadLink, "/")+1:]
+	err := downloadFile(installerFilePath, downloadLink)
 	reportMetric(t, "DownloadFail", err)
 	err = common.InstallAgent(installerFilePath)
 	reportMetric(t, "InstallFail", err)
 	common.CopyFile(configInputPath, common.ConfigOutputPath)
 	err = common.StartAgent(common.ConfigOutputPath, false, false)
 	reportMetric(t, "StartFail", err)
-	actualVersion, _ := os.ReadFile(common.InstallAgentVersionPath)
-	expectedVersion, _ := getVersionFromS3(e.Bucket)
-	if expectedVersion != string(actualVersion) {
+	data, _ := os.ReadFile(common.InstallAgentVersionPath)
+	actualVersion := strings.TrimSpace(string(data))
+	expectedVersion, _ := getVersionFromS3()
+	expectedVersion = strings.TrimSpace(expectedVersion)
+	log.Printf("expected version: %s, actual version: %s", expectedVersion, actualVersion)
+	if expectedVersion != actualVersion {
 		err = errors.New("agent version mismatch")
 	}
 	reportMetric(t, "VersionFail", err)
@@ -65,45 +73,63 @@ func reportMetric(t *testing.T, name string, err error) {
 	require.NoError(t, err)
 }
 
-func getVersionFromS3(bucket string) (string, error) {
+func getVersionFromS3() (string, error) {
 	filename := "./CWAGENT_VERSION"
-	// Assuming the release process will create this s3 key.
-	key := "release/CWAGENT_VERSION"
-	err := awsservice.DownloadFile(bucket, key, filename)
+	err := downloadFile(filename, versionLink)
 	if err != nil {
 		return "", err
 	}
 	v, err := os.ReadFile(filename)
 	return string(v), err
 }
 
-func setupCron(bucket, key string) {
+func setupCron() {
 	// default to us-west-2
 	region := os.Getenv("AWS_REGION")
 	if region == "" {
 		region = "us-west-2"
 	}
-
 	// Need to create a temporary file at low privilege.
 	// Then use sudo to copy it to the CRON directory.
 	src := "resources/canary_test_cron"
-	updateCron(src, region, bucket, key)
+	updateCron(src, region)
 	dst := "/etc/cron.d/canary_test_cron"
 	common.CopyFile(src, dst)
 }
 
-func updateCron(filepath, region, bucket, s3Key string) {
+func updateCron(filepath, region string) {
 	// cwd will be something like .../amazon-cloudwatch-agent-test/test/canary/
 	cwd, err := os.Getwd()
 	log.Printf("cwd %s", cwd)
 	if err != nil {
 		log.Fatalf("error: Getwd(), %s", err)
 	}
-	s := fmt.Sprintf("MAILTO=\"\"\n*/5 * * * * ec2-user cd %s && AWS_REGION=%s go test ./ -count=1 -computeType=EC2 -bucket=%s -s3key=%s > ./cron_run.log\n",
-		cwd, region, bucket, s3Key)
+	s := fmt.Sprintf("MAILTO=\"\"\n*/5 * * * * ec2-user cd %s && AWS_REGION=%s go test ./ -count=1 -computeType=EC2 > ./cron_run.log\n",
+		cwd, region)
 	b := []byte(s)
 	err = os.WriteFile(filepath, b, 0644)
 	if err != nil {
 		log.Println("error: creating temp cron file")
 	}
 }
+
+// downloadFile will download from a given url to a file. It will
+// write as it downloads (useful for large files).
+func downloadFile(filepath string, url string) error {
+	log.Printf("downloading from %s to %s", url, filepath)
+	// Get the data
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	// Create the file
+	out, err := os.Create(filepath)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+	// Write the body to file
+	_, err = io.Copy(out, resp.Body)
+	return err
+}