Create public uptime checks

Console

To create an uptime check by using the Google Cloud console, do the following:

1. In the Google Cloud console, go to the  Uptime checks page:

   Go to Uptime checks

   If you use the search bar to find this page, then select the result whose subheading is Monitoring.

2. In the toolbar of the Google Cloud console, select your Google Cloud project. For App Hub configurations, select the App Hub host project or management project.

3. Click Create Uptime Check.

   

4. Specify the target of the uptime check:

   1. Select the protocol. You can select HTTP, HTTPS, or TCP.

   2. Choose one of the following resource types:

      • URL: Any IPv4 address or hostname. Path and port are entered separately.
      • Kubernetes LoadBalancer Service: Kubernetes Service of LoadBalancer type.
      • Cloud Run Service: If you select a Cloud Run service as the target of an uptime check, then make sure that you have the run.routes.invoke permission on that service.
      • App Engine: App Engine applications (modules).
      • Instance: Compute Engine or AWS EC2 instances.
      • Elastic Load Balancer: AWS load balancer.

   3. Enter the protocol-specific fields:

      • For TCP checks, enter the port.

      • For HTTP and HTTPS checks, you can enter a path within your host or resource. All uptime checks that use these protocols send a request to http://target/path. In this expression, for a URL resource, target is a hostname or IP address. For an App Engine resource, target is a hostname derived from the service name. For instance and load balancer resources, target is an IP address derived from the name you provided for the resource or the group of resources.

        If you leave the path field blank or if you set the value to /, then the request is issued to http://target/.

        For example, to issue an uptime check to the URL resource example.com/tester, set the Hostname field to example.com and the Path field to /tester.

        Suppose you've deployed a server to App Engine with a dispatcher that supports / and /hello. To issue the uptime check to the '/' handler, leave the Path field empty. To issue the uptime check to the /hello handler, set the value of the Path field to /hello.

   4. Enter the resource-specific fields:

      • For URL resources, enter the hostname in the Hostname field. For example, enter example.com.

      • For App Engine resources, enter the service name in the Service field.

      • For Elastic Load Balancer and Instance resources, complete the Applies to field as follows:

        • To issue an uptime check to a single instance or load balancer, select Single and then use the menu to select the specific instance or load balancer.
        • To issue an uptime check to a Monitoring group, select Group, and then use the menu to select the group name.

   5. Optional: To set how often the uptime check executes, use the Check frequency field.

   6. Optional: To select checker regions, or to configure SSL certificates, authentication, headers, and ports for HTTP and HTTPS checks, click More target options:

      • Regions: Select the regions where the uptime checks are to receive requests. An uptime check must have at least three checkers. There's one checker in all regions except the United States, which has three checkers. The default setting, Global, includes all regions.
      • ICMP Pings: Configure the uptime check to send up to three pings. For more information, see Use ICMP pings.
      • Request Method: For HTTP checks, select the request method.
      • Body: For HTTP POST checks, enter the URL encoded body; you must do the encoding yourself. For all other checks, leave this field empty.
      • Host header: Fill this field in to check virtual hosts. This field isn't available for TCP checks.
      • Port: Specify a port number.
      • Custom Headers: Supply custom headers, and encrypt them if desired. Encryption hides the values of the header in the form. Use encryption for headers related to authentication that you don't want visible to others.

      • Authentication: These values are sent as an Authorization header. This field isn't available for TCP checks.

        Choose from the following options:

        • Basic Authentication: Provide a single username and password. Passwords are always hidden in the form.
        • Service Agent Authentication: When enabled an identity token is generated for the monitoring service agent. This option is available only for HTTPS checks.

      • SSL Certificate Validation: If you selected HTTPS for a URL resource, then by default, the service attempts to connect over HTTPS and validate the SSL certificate. Uptime checks fail when a URL has an invalid certificate. Reasons for an invalid certificate include the following:

        • An expired certificate
        • A self-signed certificate
        • A certificate with a domain-name mismatch
        • A certificate that uses the Authority Information Access (AIA) extension.

        To force an HTTPS uptime check to validate the SSL certificate, select Validate SSL certificates.

        To disable SSL certificate validation, clear Validate SSL certificates.

        If you have SSL Certificates with AIA Extensions, then you must disable SSL certificate validation. These types of certificates aren't supported and fail the validation sequence. Typically, the error message is "Responded with SSL handshake Error in 10000 ms".

        You can use the metric monitoring.googleapis.com/uptime_check/time_until_ssl_cert_expires to create an alerting policy that notifies you before your certificate expires. For more information, see Sample policies: Uptime-check policy.

        Select Validate SSL certificates checkbox.

5. Click Continue and configure the response requirements. All settings in this section have default values:

   • To change the timeout period for the uptime check, use the Response Timeout field. An uptime check fails when no response is received from more than one location within this period.

   • To configure the uptime check to perform content matching, ensure that the toggle label is Content matching is enabled:

     • Select the Response Content Match Type from the menu of options. This field determines how the response content is compared to the returned data. For example, assume that the response content is abcd and the content match type is Contains. The uptime check is successful only when the response data contains abcd. For more information, see Validate response data.
     • Enter the Response content. The response content must be a string no longer than 1024 bytes. In the API, this field is the ContentMatcher object.

   • To prevent log entries from being created due to uptime checks, clear Log check failures.

   • For the HTTP uptime checks, configure the acceptable response codes. By default, HTTP uptime checks mark any 2xx response as a successful response.

6. Click Continue and configure notifications.

   To be notified when an uptime check fails, create an alerting policy and configure notification channels for that policy:

   1. Optional: Update the name of the alerting policy.
   2. Optional: In the Duration field, select how long the uptime checks must fail before notifications are sent. By default, notifications are sent when at least two regions report uptime check failures for a duration of at least one minute.

   3. In the box labeled Notification channels, click arrow_drop_down Menu, select the channels to add, and then click OK.

      In the menu, the notification channels are grouped alphabetically for each channel type.

   If you don't want to create an alerting policy, then ensure that the text of the toggle button is Do not create an alert.

7. Click Continue and complete your uptime check:

   1. Enter a descriptive title for the uptime check.

   2. Optional: To add user-defined labels to your uptime check, do the following:

      1. Click expand_more Show user labels.
      2. In the Key field, enter a name for the label. Label names must start with a lowercase letter, and they can contain lowercase letters, numerals, underscores, and dashes. For example, enter severity.
      3. In the Value field, enter a value for your label. Label values can contain lowercase letters, numerals, underscores, and dashes. For example, enter critical.
      4. For each additional label, click Add user label and then enter the key and value of the label.

   3. To verify your uptime check configuration, click Test. If the result isn't what you expect, see Check failures, correct your configuration, and then repeat the verification step.

   4. Click Create. If you select Create and a required field isn't populated, then an error message is displayed.

gcloud

To create the uptime check, run the gcloud monitoring uptime create command:

gcloud monitoring uptime create DISPLAY_NAME REQUIRED_FLAGS OPTIONAL_FLAGS --project=PROJECT_ID

Before you run the previous command, replace the following:

• PROJECT_ID: The identifier of the project. For App Hub configurations, select the App Hub host project or management project.

• DISPLAY_NAME: The name for your uptime check.

• REQUIRED_FLAGS: Configure to specify the resource probed by the uptime check. For example, the following command creates an uptime check that tests the URL EXAMPLE.com for a particular project:

  gcloud monitoring uptime create DISPLAY_NAME \
  --resource-labels=host=EXAMPLE.com,project_id=PROJECT_ID \
  --resource-type=uptime-url
  

  The previous command specifies values for each label required by the resource type uptime-url.

• OPTIONAL_FLAGS: Configure these flags to override default values. For example, you must set the --protocol flag when the protocol isn't http.

Terraform

To learn how to apply or remove a Terraform configuration, see Basic Terraform commands. For more information, see the Terraform provider reference documentation.

To create an uptime check and an alerting policy to monitor that check, do the following:

1. Install and configure Terraform for you project. For App Hub configurations, select the App Hub host project or management project.

2. Edit your Terraform configuration file and add a google_monitoring_uptime_check_config resource, and then apply the configuration file.

   The following example illustrates a configuration that checks a public URL:

   resource "google_monitoring_uptime_check_config" "example" {
       display_name = "example"
       timeout      = "60s"
   
       http_check {
           port = "80"
           request_method = "GET"
       }
   
       monitored_resource {
           type = "uptime_url"
           labels = {
               project_id = "PROJECT_ID"
               host="EXAMPLE.com"
           }
       }
   
       checker_type = "STATIC_IP_CHECKERS"
   }
   

   In the previous expression:

   • PROJECT_ID is the ID of your project. For App Hub configurations, select the App Hub host project or management project.
   • EXAMPLE.com is the Host URL.

3. Optional: Create a notification channel and an alerting policy:

   The following steps use the Google Cloud console to create the notification channel and alerting policy. This approach ensures that the alerting policy only monitors the data generated by your uptime check.

   1. To create a notification channel, do the following:

      1. In the Google Cloud console, go to the notifications Alerting page:

         Go to Alerting

         If you use the search bar to find this page, then select the result whose subheading is Monitoring.

      2. In the toolbar of the Google Cloud console, select your Google Cloud project. For App Hub configurations, select the App Hub host project or management project.
      3. Select Manage notification channels.
      4. Go to the type of channel that you want to add, click Add, and then complete the dialog.

   2. To create an alerting policy, do the following:

      1. In the Google Cloud console, go to the  Uptime checks page:

         Go to Uptime checks

         If you use the search bar to find this page, then select the result whose subheading is Monitoring.

      2. In the toolbar of the Google Cloud console, select your Google Cloud project. For App Hub configurations, select the App Hub host project or management project.
      3. Locate your uptime check, select more_vert More, and then select Add alert policy.
      4. In the dialog, go to the Notifications and name section, expand Notification Channels, and make your selections.
      5. Name the alerting policy and then click Create policy.

   You can create an alerting policy by adding a google_monitoring_alert_policy resource to your configuration file and applying the new configuration.

C#

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

public static object CreateUptimeCheck(string projectId, string hostName,
    string displayName)
{
    // Define a new config.
    var config = new UptimeCheckConfig()
    {
        DisplayName = displayName,
        MonitoredResource = new MonitoredResource()
        {
            Type = "uptime_url",
            Labels = { { "host", hostName } }
        },
        HttpCheck = new UptimeCheckConfig.Types.HttpCheck()
        {
            Path = "/",
            Port = 80,
        },
        Timeout = TimeSpan.FromSeconds(10).ToDuration(),
        Period = TimeSpan.FromMinutes(5).ToDuration()
    };
    // Create a client.
    var client = UptimeCheckServiceClient.Create();
    ProjectName projectName = new ProjectName(projectId);
    // Create the config.
    var newConfig = client.CreateUptimeCheckConfig(
        projectName,
        config,
        CallSettings.FromExpiration(
            Expiration.FromTimeout(
                TimeSpan.FromMinutes(2))));
    Console.WriteLine(newConfig.Name);
    return 0;
}

Java

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

private static void createUptimeCheck(
    String projectId, String displayName, String hostName, String pathName) throws IOException {
  CreateUptimeCheckConfigRequest request =
      CreateUptimeCheckConfigRequest.newBuilder()
          .setParent(ProjectName.format(projectId))
          .setUptimeCheckConfig(
              UptimeCheckConfig.newBuilder()
                  .setDisplayName(displayName)
                  .setMonitoredResource(
                      MonitoredResource.newBuilder()
                          .setType("uptime_url")
                          .putLabels("host", hostName))
                  .setHttpCheck(HttpCheck.newBuilder().setPath(pathName).setPort(80))
                  .setTimeout(Duration.newBuilder().setSeconds(10))
                  .setPeriod(Duration.newBuilder().setSeconds(300)))
          .build();
  try (UptimeCheckServiceClient client = UptimeCheckServiceClient.create()) {
    UptimeCheckConfig config = client.createUptimeCheckConfig(request);
    System.out.println("Uptime check created: " + config.getName());
  } catch (Exception e) {
    usage("Exception creating uptime check: " + e.toString());
    throw e;
  }
}

Go

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// createGet creates an example uptime check on a GET request.
func createGet(w io.Writer, projectID string) (*monitoringpb.UptimeCheckConfig, error) {
	ctx := context.Background()
	client, err := monitoring.NewUptimeCheckClient(ctx)
	if err != nil {
		return nil, fmt.Errorf("NewUptimeCheckClient: %w", err)
	}
	defer client.Close()
	req := &monitoringpb.CreateUptimeCheckConfigRequest{
		Parent: "projects/" + projectID,
		UptimeCheckConfig: &monitoringpb.UptimeCheckConfig{
			DisplayName: "new GET uptime check",
			Resource: &monitoringpb.UptimeCheckConfig_MonitoredResource{
				MonitoredResource: &monitoredres.MonitoredResource{
					Type: "uptime_url",
					Labels: map[string]string{
						"host": "example.com",
					},
				},
			},
			CheckRequestType: &monitoringpb.UptimeCheckConfig_HttpCheck_{
				HttpCheck: &monitoringpb.UptimeCheckConfig_HttpCheck{
					RequestMethod: monitoringpb.UptimeCheckConfig_HttpCheck_GET,
					Path:          "/",
					Port:          80,
				},
			},
			Timeout: &duration.Duration{Seconds: 10},
			Period:  &duration.Duration{Seconds: 300},
		},
	}
	config, err := client.CreateUptimeCheckConfig(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("CreateUptimeCheckConfig GET: %w", err)
	}
	fmt.Fprintf(w, "Successfully created GET uptime check %q\n", config.GetDisplayName())
	return config, nil
}

// createPost creates an example uptime check on a POST request.
func createPost(w io.Writer, projectID string) (*monitoringpb.UptimeCheckConfig, error) {
	ctx := context.Background()
	client, err := monitoring.NewUptimeCheckClient(ctx)
	if err != nil {
		return nil, fmt.Errorf("NewUptimeCheckClient: %w", err)
	}
	defer client.Close()
	req := &monitoringpb.CreateUptimeCheckConfigRequest{
		Parent: "projects/" + projectID,
		UptimeCheckConfig: &monitoringpb.UptimeCheckConfig{
			DisplayName: "new POST uptime check",
			Resource: &monitoringpb.UptimeCheckConfig_MonitoredResource{
				MonitoredResource: &monitoredres.MonitoredResource{
					Type: "uptime_url",
					Labels: map[string]string{
						"host": "example.com",
					},
				},
			},
			CheckRequestType: &monitoringpb.UptimeCheckConfig_HttpCheck_{
				HttpCheck: &monitoringpb.UptimeCheckConfig_HttpCheck{
					RequestMethod: monitoringpb.UptimeCheckConfig_HttpCheck_POST,
					ContentType:   monitoringpb.UptimeCheckConfig_HttpCheck_URL_ENCODED,
					Path:          "/",
					Port:          80,
					Body:          []byte(base64.URLEncoding.EncodeToString([]byte("key: value"))),
				},
			},
			Timeout: &duration.Duration{Seconds: 10},
			Period:  &duration.Duration{Seconds: 300},
		},
	}
	config, err := client.CreateUptimeCheckConfig(ctx, req)
	if err != nil {
		return nil, fmt.Errorf("CreateUptimeCheckConfig POST: %w", err)
	}
	fmt.Fprintf(w, "Successfully created POST uptime check %q\n", config.GetDisplayName())
	return config, nil
}

Node.js

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

// Imports the Google Cloud client library
const monitoring = require('@google-cloud/monitoring');

// Creates a client
const client = new monitoring.UptimeCheckServiceClient();

/**
 * TODO(developer): Uncomment and edit the following lines of code.
 */
// const projectId = 'YOUR_PROJECT_ID';
// const hostname = 'mydomain.com';

const request = {
  // i.e. parent: 'projects/my-project-id'
  parent: client.projectPath(projectId),
  uptimeCheckConfig: {
    displayName: 'My Uptime Check',
    monitoredResource: {
      // See the Uptime Check docs for supported MonitoredResource types
      type: 'uptime_url',
      labels: {
        host: hostname,
      },
    },
    httpCheck: {
      path: '/',
      port: 80,
    },
    timeout: {
      seconds: 10,
    },
    period: {
      seconds: 300,
    },
  },
};

// Creates an uptime check config for a GCE instance
const [uptimeCheckConfig] = await client.createUptimeCheckConfig(request);
console.log('Uptime check created:');
console.log(`ID: ${uptimeCheckConfig.name}`);
console.log(`Display Name: ${uptimeCheckConfig.displayName}`);
console.log('Resource: %j', uptimeCheckConfig.monitoredResource);
console.log('Period: %j', uptimeCheckConfig.period);
console.log('Timeout: %j', uptimeCheckConfig.timeout);
console.log(`Check type: ${uptimeCheckConfig.check_request_type}`);
console.log(
  'Check: %j',
  uptimeCheckConfig.httpCheck || uptimeCheckConfig.tcpCheck
);
console.log(
  `Content matchers: ${uptimeCheckConfig.contentMatchers
    .map(matcher => matcher.content)
    .join(', ')}`
);
console.log(`Regions: ${uptimeCheckConfig.selectedRegions.join(', ')}`);

PHP

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

use Google\Api\MonitoredResource;
use Google\Cloud\Monitoring\V3\Client\UptimeCheckServiceClient;
use Google\Cloud\Monitoring\V3\CreateUptimeCheckConfigRequest;
use Google\Cloud\Monitoring\V3\UptimeCheckConfig;

/**
 * Example:
 * ```
 * create_uptime_check($projectId, 'myproject.appspot.com', 'Test Uptime Check!');
 * ```
 *
 * @param string $projectId Your project ID
 * @param string $hostName
 * @param string $displayName
 */
function create_uptime_check($projectId, $hostName = 'example.com', $displayName = 'New uptime check')
{
    $projectName = 'projects/' . $projectId;
    $uptimeCheckClient = new UptimeCheckServiceClient([
        'projectId' => $projectId,
    ]);

    $monitoredResource = new MonitoredResource();
    $monitoredResource->setType('uptime_url');
    $monitoredResource->setLabels(['host' => $hostName]);

    $uptimeCheckConfig = new UptimeCheckConfig();
    $uptimeCheckConfig->setDisplayName($displayName);
    $uptimeCheckConfig->setMonitoredResource($monitoredResource);
    $createUptimeCheckConfigRequest = (new CreateUptimeCheckConfigRequest())
        ->setParent($projectName)
        ->setUptimeCheckConfig($uptimeCheckConfig);

    $uptimeCheckConfig = $uptimeCheckClient->createUptimeCheckConfig($createUptimeCheckConfigRequest);

    printf('Created an uptime check: %s' . PHP_EOL, $uptimeCheckConfig->getName());
}

Python

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

def create_uptime_check_config_get(
    project_id: str, host_name: str = None, display_name: str = None
) -> uptime.UptimeCheckConfig:
    """Creates a new uptime check configuration

    Args:
        project_id: Google Cloud project id where the uptime check is created
        host_name: An example label's value for the "host" label
        display_name: A human friendly name of the configuration

    Returns:
        A structure that describes a new created uptime check
    """
    config = monitoring_v3.UptimeCheckConfig()
    config.display_name = display_name or "New GET uptime check"
    config.monitored_resource = {
        "type": "uptime_url",
        "labels": {"host": host_name or "example.com"},
    }
    config.http_check = {
        "request_method": monitoring_v3.UptimeCheckConfig.HttpCheck.RequestMethod.GET,
        "path": "/",
        "port": 80,
    }
    config.timeout = {"seconds": 10}
    config.period = {"seconds": 300}

    client = monitoring_v3.UptimeCheckServiceClient()
    new_config = client.create_uptime_check_config(
        request={"parent": project_id, "uptime_check_config": config}
    )
    pprint.pprint(new_config)
    return new_config


def create_uptime_check_config_post(
    project_id: str, host_name: str = None, display_name: str = None
) -> uptime.UptimeCheckConfig:
    """Creates a new uptime check configuration

    Args:
        project_id: Google Cloud project id where the uptime check is created
        host_name: An example label's value for the "host" label
        display_name: A human friendly name of the configuration

    Returns:
        A structure that describes a new created uptime check
    """
    config = monitoring_v3.UptimeCheckConfig()
    config.display_name = display_name or "New POST uptime check"
    config.monitored_resource = {
        "type": "uptime_url",
        "labels": {"host": host_name or "example.com"},
    }
    config.http_check = {
        "request_method": monitoring_v3.UptimeCheckConfig.HttpCheck.RequestMethod.POST,
        "content_type": monitoring_v3.UptimeCheckConfig.HttpCheck.ContentType.URL_ENCODED,
        "body": "foo=bar".encode("utf-8"),
        "path": "/",
        "port": 80,
    }
    config.timeout = {"seconds": 10}
    config.period = {"seconds": 300}

    client = monitoring_v3.UptimeCheckServiceClient()
    new_config = client.create_uptime_check_config(
        request={"parent": project_id, "uptime_check_config": config}
    )
    pprint.pprint(new_config)
    return new_config

Ruby

To authenticate to Monitoring, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

gem "google-cloud-monitoring"
require "google/cloud/monitoring"

def create_uptime_check_config project_id: nil, host_name: nil, display_name: nil
  client = Google::Cloud::Monitoring.uptime_check_service
  project_name = client.project_path project: project_id
  config = {
    display_name:       display_name.nil? ? "New uptime check" : display_name,
    monitored_resource: {
      type:   "uptime_url",
      labels: { "host" => host_name.nil? ? "example.com" : host_name }
    },
    http_check:         { path: "/", port: 80 },
    timeout:            { seconds: 10 },
    period:             { seconds: 300 }
  }
  new_config = client.create_uptime_check_config \
    parent:              project_name,
    uptime_check_config: config
  puts new_config.name
  new_config
end

REST

To create an uptime check, call the projects.uptimeCheckConfigs.create method. Set the method's parameters as follows:

• parent: Required. The project in which to create the uptime check. For App Hub configurations, select the App Hub host project or management project. This field has the following format:

  projects/PROJECT_ID
  

• The request body must contain an UptimeCheckConfig object for the new uptime check. This page provides information about a few fields. For complete documentation on this object and its fields, see UptimeCheckConfig:

  • Leave the name field of the configuration object blank. The system sets this field when it constructs the response configuration object.

  • If you are configuring an HTTP or HTTPS check, then you must populate the HttpCheck field of the UptimeCheckConfig object. In this object, set the requestMethod field as GET or POST. If this field is omitted or set to METHOD_UNSPECIFIED, then a GET request is issued.

    If you are configuring a POST request, then complete the contentType, optional customContentType, and body fields.

The create method returns the UptimeCheckConfig object for the new configuration.

If the created uptime configuration doesn't work as expected, see the Check failures section on this page.

There can be a delay of up to 5 minutes before the uptime check results start to flow into Monitoring. During that time, the uptime check dashboard reports the status as "no data available."

Use ICMP pings

To help you troubleshoot failed public uptime checks, you can configure your uptime checks to send up to 3 ICMP pings during the check. The pings can help you distinguish between failures caused, for example, by network connectivity problems and by timeouts in your application.

By default, uptime checks don't send pings. Each ping adds some latency to the uptime check. Private uptime checks can't send pings.

When a public uptime check fails, the results of the pings are written to Cloud Logging logs. If the ping fails, then the following fields are added to the httpRequest field in the log entry:

• rtt_usec: round-trip time for each unsuccessful ping request.
• unreachable_count: number of ping requests that returned the status code ICMP_DEST_UNREACH.
• no_answer_count: number of ping requests that timed out and returned no response.

The results of pings for successful uptime checks aren't logged.

Configure pings

Each uptime-check configuration includes either an HttpCheck object or a TcpCheck object. Both of these objects include a pingConfig field. Use this field to specify the number of ICMP pings to include with each check, up to 3. By default, no pings are sent.

To configure pings, do one of the following:

• When using the Google Cloud console, expand More target options and enter a value in the ICMP Pings field.

• When using the Cloud Monitoring API, use the PingConfig object, which has the following structure:

  {
    "pingsCount": integer
  }
  

  For more information about using the Monitoring API for uptime-check configurations, see Create an uptime check: API or Edit an uptime check: API.

Verify your uptime check

When you create an uptime check in the Google Cloud console, you can test the configuration before saving.

Successful checks

An uptime check is successful when the following conditions are true:

• The HTTP status matches the criteria you selected.
• The response has no required content or, a search of the response for the required content is successful.

Failed checks

The following are some possible causes of an uptime check failure:

• Connection Error - Refused: If you are using the default HTTP connection type, check that you have a web server installed that is responding to HTTP requests. A connection error can happen on a new instance if you haven't installed a web server; see the Quickstart for Compute Engine. If you use an HTTPS connection type, you might have to perform additional configuration steps. For firewall issues, see List uptime-check server IP addresses.
• Name or service not found: The host name might be incorrect.

• 403 Forbidden: The service is returning an error code to the uptime checker. For example, the default Apache web server configuration returns this code under Amazon Linux, but it returns code 200 (Success) under some other Linux versions. See the LAMP tutorial for Amazon Linux or your web server's documentation.

  If you see this error message and the target of your uptime check is a Cloud Run service, then make sure that you have the run.routes.invoke on that service.

• 404 Not found: The path might be incorrect.

• 408 Request timeout, or no response: The port number might be incorrect, the service might not be running, the service might be inaccessible, or the timeout might be too low. Check that your firewall allows traffic from the uptime servers; see List uptime-check server IP addresses. The timeout limit is specified as part of the Response Validation options.

  A request timeout might occur due to network congestion. For example, due to temporary network congestion, you might notice that one checker fails but all other checkers succeed. The failure of a single checker doesn't cause a notification when your alerting policy uses the default configuration.

If your uptime check is configured to send pings, then the results of pings for failed uptime checks are written to Cloud Logging. For more information, see Use ICMP pings.

What's next

• Manage uptime checks
• Create alerting policies for uptime checks
• List uptime-check server IP addresses
• Chart uptime-check metrics