Google Compute Engine Region Backend Service

This page shows how to write Terraform for Compute Engine Region Backend Service and write them securely.

google_compute_region_backend_service (Terraform)

The Region Backend Service in Compute Engine can be configured in Terraform with the resource name google_compute_region_backend_service. The following sections describe 3 examples of how to use the resource and its parameters.

Example Usage from GitHub

lb.tf#L24
resource "google_compute_region_backend_service" "k3s-api-server-internal" {
  name                  = "k3s-api-server-internal"
  region                = var.region
  load_balancing_scheme = "INTERNAL"
  health_checks         = [google_compute_health_check.k3s-health-check-internal.id]
  backend {
loadbalancer.tf#L11
resource "google_compute_region_backend_service" "malware-scanner" {
  name                  = "malware-scanner"
  health_checks         = [
    google_compute_health_check.malware-scanner.self_link]
  protocol              = "TCP"
  timeout_sec           = 10
main.tf#L7
resource "google_compute_region_backend_service" "default" {
  name                            = "region-service"
  region                          = "us-central1"
  health_checks                   = [google_compute_health_check.default.id]
  connection_draining_timeout_sec = 10
  session_affinity                = "CLIENT_IP"

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Parameters

Lifetime of cookies in seconds if session_affinity is GENERATED_COOKIE. If set to 0, the cookie is non-persistent and lasts only until the end of the browser session (or equivalent). The maximum allowed value for TTL is one day. When the load balancing scheme is INTERNAL, this field is not used.

Time for which instance will be drained (not accept new connections, but still work to finish started).

Creation timestamp in RFC3339 text format.

An optional description of this resource.

If true, enable Cloud CDN for this RegionBackendService.

Fingerprint of this resource. A hash of the contents stored in this object. This field is used in optimistic locking.

The set of URLs to HealthCheck resources for health checking this RegionBackendService. Currently at most one health check can be specified. A health check must be specified unless the backend service uses an internet or serverless NEG as a backend.

Indicates what kind of load balancing this regional backend service will be used for. A backend service created for one type of load balancing cannot be used with the other(s). Default value: "INTERNAL" Possible values: ["EXTERNAL", "INTERNAL", "INTERNAL_MANAGED"]

The load balancing algorithm used within the scope of the locality. The possible values are - ROUND_ROBIN - This is a simple policy in which each healthy backend is selected in round robin order. LEASTREQUEST - An O(1) algorithm which selects two random healthy hosts and picks the host which has fewer active requests. RINGHASH - The ring/modulo hash load balancer implements consistent hashing to backends. The algorithm has the property that the addition/removal of a host from a set of N hosts only affects 1/N of the requests. RANDOM - The load balancer selects a random healthy host. ORIGINAL_DESTINATION - Backend host is selected based on the client connection metadata, i.e., connections are opened to the same address as the destination address of the incoming connection before the connection was redirected to the load balancer. MAGLEV - used as a drop in replacement for the ring hash load balancer. Maglev is not as stable as ring hash but has faster table lookup build times and host selection times. For more information about Maglev, refer to https://ai.google/research/pubs/pub44824 This field is applicable only when the 'load_balancing_scheme' is set to INTERNAL_MANAGED and the 'protocol' is set to HTTP, HTTPS, or HTTP2. Possible values: ["ROUND_ROBIN", "LEAST_REQUEST", "RING_HASH", "RANDOM", "ORIGINAL_DESTINATION", "MAGLEV"]

Name of the resource. Provided by the client when the resource is created. The name must be 1-63 characters long, and comply with RFC1035. Specifically, the name must be 1-63 characters long and match the regular expression 'a-z?' which means the first character must be a lowercase letter, and all following characters must be a dash, lowercase letter, or digit, except the last character, which cannot be a dash.

The URL of the network to which this backend service belongs. This field can only be specified when the load balancing scheme is set to INTERNAL.

A named port on a backend instance group representing the port for communication to the backend VMs in that group. Required when the loadBalancingScheme is EXTERNAL, INTERNAL_MANAGED, or INTERNAL_SELF_MANAGED and the backends are instance groups. The named port must be defined on each backend instance group. This parameter has no meaning if the backends are NEGs. API sets a default of "http" if not given. Must be omitted when the loadBalancingScheme is INTERNAL (Internal TCP/UDP Load Balancing).

The protocol this RegionBackendService uses to communicate with backends. The default is HTTP. NOTE: HTTP2 is only valid for beta HTTP/2 load balancer types and may result in errors if used with the GA API. Possible values: ["HTTP", "HTTPS", "HTTP2", "SSL", "TCP", "UDP", "GRPC"]

  • region optional computed - string

The Region in which the created backend service should reside. If it is not provided, the provider region is used.

Type of session affinity to use. The default is NONE. Session affinity is not applicable if the protocol is UDP. Possible values: ["NONE", "CLIENT_IP", "CLIENT_IP_PORT_PROTO", "CLIENT_IP_PROTO", "GENERATED_COOKIE", "HEADER_FIELD", "HTTP_COOKIE"]

How many seconds to wait for the backend before considering it a failed request. Default is 30 seconds. Valid range is [1, 86400].

  • backend set block

    Specifies the balancing mode for this backend. Default value: "CONNECTION" Possible values: ["UTILIZATION", "RATE", "CONNECTION"]

    A multiplier applied to the group's maximum servicing capacity (based on UTILIZATION, RATE or CONNECTION). ~>NOTE: This field cannot be set for INTERNAL region backend services (default loadBalancingScheme), but is required for non-INTERNAL backend service. The total capacity_scaler for all backends must be non-zero. A setting of 0 means the group is completely drained, offering 0% of its available Capacity. Valid range is [0.0,1.0].

    An optional description of this resource. Provide this property when you create the resource.

    This field designates whether this is a failover backend. More than one failover backend can be configured for a given RegionBackendService.

    The fully-qualified URL of an Instance Group or Network Endpoint Group resource. In case of instance group this defines the list of instances that serve traffic. Member virtual machine instances from each instance group must live in the same zone as the instance group itself. No two backends in a backend service are allowed to use same Instance Group resource. For Network Endpoint Groups this defines list of endpoints. All endpoints of Network Endpoint Group must be hosted on instances located in the same zone as the Network Endpoint Group. Backend services cannot mix Instance Group and Network Endpoint Group backends. When the 'load_balancing_scheme' is INTERNAL, only instance groups are supported. Note that you must specify an Instance Group or Network Endpoint Group resource using the fully-qualified URL, rather than a partial URL.

    The max number of simultaneous connections for the group. Can be used with either CONNECTION or UTILIZATION balancing modes. Cannot be set for INTERNAL backend services. For CONNECTION mode, either maxConnections or one of maxConnectionsPerInstance or maxConnectionsPerEndpoint, as appropriate for group type, must be set.

    The max number of simultaneous connections that a single backend network endpoint can handle. Cannot be set for INTERNAL backend services. This is used to calculate the capacity of the group. Can be used in either CONNECTION or UTILIZATION balancing modes. For CONNECTION mode, either maxConnections or maxConnectionsPerEndpoint must be set.

    The max number of simultaneous connections that a single backend instance can handle. Cannot be set for INTERNAL backend services. This is used to calculate the capacity of the group. Can be used in either CONNECTION or UTILIZATION balancing modes. For CONNECTION mode, either maxConnections or maxConnectionsPerInstance must be set.

    The max requests per second (RPS) of the group. Cannot be set for INTERNAL backend services. Can be used with either RATE or UTILIZATION balancing modes, but required if RATE mode. Either maxRate or one of maxRatePerInstance or maxRatePerEndpoint, as appropriate for group type, must be set.

    The max requests per second (RPS) that a single backend network endpoint can handle. This is used to calculate the capacity of the group. Can be used in either balancing mode. For RATE mode, either maxRate or maxRatePerEndpoint must be set. Cannot be set for INTERNAL backend services.

    The max requests per second (RPS) that a single backend instance can handle. This is used to calculate the capacity of the group. Can be used in either balancing mode. For RATE mode, either maxRate or maxRatePerInstance must be set. Cannot be set for INTERNAL backend services.

    Used when balancingMode is UTILIZATION. This ratio defines the CPU utilization target for the group. Valid range is [0.0, 1.0]. Cannot be set for INTERNAL backend services.

  • cdn_policy list block

    Maximum number of seconds the response to a signed URL request will be considered fresh, defaults to 1hr (3600s). After this time period, the response will be revalidated before being served. When serving responses to signed URL requests, Cloud CDN will internally behave as though all responses from this backend had a "Cache-Control: public, max-age=[TTL]" header, regardless of any existing Cache-Control header. The actual headers served in responses will not be altered.

    • cache_key_policy list block

      If true requests to different hosts will be cached separately.

      If true, http and https requests will be cached separately.

      If true, include query string parameters in the cache key according to query_string_whitelist and query_string_blacklist. If neither is set, the entire query string will be included. If false, the query string will be excluded from the cache key entirely.

      Names of query string parameters to exclude in cache keys. All other parameters will be included. Either specify query_string_whitelist or query_string_blacklist, not both. '&' and '=' will be percent encoded and not treated as delimiters.

      Names of query string parameters to include in cache keys. All other parameters will be excluded. Either specify query_string_whitelist or query_string_blacklist, not both. '&' and '=' will be percent encoded and not treated as delimiters.

  • circuit_breakers list block

    The maximum number of connections to the backend cluster. Defaults to 1024.

    The maximum number of pending requests to the backend cluster. Defaults to 1024.

    The maximum number of parallel requests to the backend cluster. Defaults to 1024.

    Maximum requests for a single backend connection. This parameter is respected by both the HTTP/1.1 and HTTP/2 implementations. If not specified, there is no limit. Setting this parameter to 1 will effectively disable keep alive.

    The maximum number of parallel retries to the backend cluster. Defaults to 3.

  • consistent_hash list block

    The hash based on the value of the specified header field. This field is applicable if the sessionAffinity is set to HEADER_FIELD.

    The minimum number of virtual nodes to use for the hash ring. Larger ring sizes result in more granular load distributions. If the number of hosts in the load balancing pool is larger than the ring size, each host will be assigned a single virtual node. Defaults to 1024.

    • http_cookie list block

      Name of the cookie.

      Path to set for the cookie.

      • ttl list block

        Span of time that's a fraction of a second at nanosecond resolution. Durations less than one second are represented with a 0 seconds field and a positive nanos field. Must be from 0 to 999,999,999 inclusive.

        Span of time at a resolution of a second. Must be from 0 to 315,576,000,000 inclusive.

  • failover_policy list block

    On failover or failback, this field indicates whether connection drain will be honored. Setting this to true has the following effect: connections to the old active pool are not drained. Connections to the new active pool use the timeout of 10 min (currently fixed). Setting to false has the following effect: both old and new connections will have a drain timeout of 10 min. This can be set to true only if the protocol is TCP. The default is false.

    This option is used only when no healthy VMs are detected in the primary and backup instance groups. When set to true, traffic is dropped. When set to false, new connections are sent across all VMs in the primary group. The default is false.

    The value of the field must be in [0, 1]. If the ratio of the healthy VMs in the primary backend is at or below this number, traffic arriving at the load-balanced IP will be directed to the failover backend. In case where 'failoverRatio' is not set or all the VMs in the backup backend are unhealthy, the traffic will be directed back to the primary backend in the "force" mode, where traffic will be spread to the healthy VMs with the best effort, or to all VMs when no VM is healthy. This field is only used with l4 load balancing.

  • log_config list block

    Whether to enable logging for the load balancer traffic served by this backend service.

    This field can only be specified if logging is enabled for this backend service. The value of the field must be in [0, 1]. This configures the sampling rate of requests to the load balancer where 1.0 means all logged requests are reported and 0.0 means no logged requests are reported. The default value is 1.0.

  • outlier_detection list block

    Number of errors before a host is ejected from the connection pool. When the backend host is accessed over HTTP, a 5xx return code qualifies as an error. Defaults to 5.

    The number of consecutive gateway failures (502, 503, 504 status or connection errors that are mapped to one of those status codes) before a consecutive gateway failure ejection occurs. Defaults to 5.

    The percentage chance that a host will be actually ejected when an outlier status is detected through consecutive 5xx. This setting can be used to disable ejection or to ramp it up slowly. Defaults to 100.

    The percentage chance that a host will be actually ejected when an outlier status is detected through consecutive gateway failures. This setting can be used to disable ejection or to ramp it up slowly. Defaults to 0.

    The percentage chance that a host will be actually ejected when an outlier status is detected through success rate statistics. This setting can be used to disable ejection or to ramp it up slowly. Defaults to 100.

    Maximum percentage of hosts in the load balancing pool for the backend service that can be ejected. Defaults to 10%.

    The number of hosts in a cluster that must have enough request volume to detect success rate outliers. If the number of hosts is less than this setting, outlier detection via success rate statistics is not performed for any host in the cluster. Defaults to 5.

    The minimum number of total requests that must be collected in one interval (as defined by the interval duration above) to include this host in success rate based outlier detection. If the volume is lower than this setting, outlier detection via success rate statistics is not performed for that host. Defaults to 100.

    This factor is used to determine the ejection threshold for success rate outlier ejection. The ejection threshold is the difference between the mean success rate, and the product of this factor and the standard deviation of the mean success rate: mean - (stdev * success_rate_stdev_factor). This factor is divided by a thousand to get a double. That is, if the desired factor is 1.9, the runtime value should be 1900. Defaults to 1900.

    • base_ejection_time list block

      Span of time that's a fraction of a second at nanosecond resolution. Durations less than one second are represented with a 0 'seconds' field and a positive 'nanos' field. Must be from 0 to 999,999,999 inclusive.

      Span of time at a resolution of a second. Must be from 0 to 315,576,000,000 inclusive.

    • interval list block

      Span of time that's a fraction of a second at nanosecond resolution. Durations less than one second are represented with a 0 'seconds' field and a positive 'nanos' field. Must be from 0 to 999,999,999 inclusive.

      Span of time at a resolution of a second. Must be from 0 to 315,576,000,000 inclusive.

  • timeouts single block

Explanation in Terraform Registry

A Region Backend Service defines a regionally-scoped group of virtual machines that will serve traffic for load balancing. To get more information about RegionBackendService, see:

Tips: Best Practices for The Other Google Compute Engine Resources

In addition to the google_compute_disk, Google Compute Engine has the other resources that should be configured for security reasons. Please check some examples of those resources and precautions.

risk-label

google_compute_disk

Ensure the encryption key for your GCE disk is stored securely

It is better to store the encryption key for your GCE disk securely. Secret Manager could be used instead.

risk-label

google_compute_firewall

Ensure your VPC firewall blocks unwanted outbound traffic

It is better to block unwanted outbound traffic not to expose resources in the VPC to unwanted attacks.

risk-label

google_compute_instance

Ensure appropriate service account is assigned to your GCE instance

It is better to create a custom service account for the instance and assign it.

risk-label

google_compute_project_metadata

Ensure OS login for your GCE instances is enabled at project level

It is better to enable OS login for your GCE instances. Enabling OS login ensures that SSH keys used to connect to instances are mapped with IAM users, allowing centralized and automated SSH key management.

risk-label

google_compute_ssl_policy

Ensure to use modern TLS protocols

It's better to adopt TLS v1.2+ instead of outdated TLS protocols.

risk-label

google_compute_subnetwork

Ensure VPC flow logging is enabled

It is better to enable VPC flow logging. VPC flow logging allows us to audit traffic in your network.

Review your Google Compute Engine settings

In addition to the above, there are other security points you should be aware of making sure that your .tf files are protected in Shisho Cloud.

Frequently asked questions

What is Google Compute Engine Region Backend Service?

Google Compute Engine Region Backend Service is a resource for Compute Engine of Google Cloud Platform. Settings can be wrote in Terraform.

Where can I find the example code for the Google Compute Engine Region Backend Service?

For Terraform, the jsiebens/k3s-on-gcp, gashirar/gcs-malware-scanner-terraform and nrayavaram/Compute_Region_backend source code examples are useful. See the Terraform Example section for further details.