Configure rate limiting

This page contains information about configuring Google Cloud Armor rules to enforce per-client rate limits by configuring a throttle or rate-based ban action. Before you configure rate limiting, make sure that you're familiar with the information in the rate limiting overview.

Before you begin

The following sections explain all of the Identity and Access Management (IAM) roles and permissions required to configure Google Cloud Armor security policies. For the use cases in this document, you only need the compute.securityPolicies.create permission.

Set up IAM permissions for Google Cloud Armor security policies

The following operations require the Identity and Access Management (IAM) Compute Security Admin role (roles/compute.securityAdmin):

  • Configuring, modifying, updating, and deleting a Google Cloud Armor security policy
  • Using the following API methods:
    • SecurityPolicies insert
    • SecurityPolicies delete
    • SecurityPolicies patch
    • SecurityPolicies addRule
    • SecurityPolicies patchRule
    • SecurityPolicies removeRule

A user with the Compute Network Admin role (roles/compute.networkAdmin) can perform the following operations:

  • Setting a Google Cloud Armor security policy for a backend service
  • Using the following API methods:
    • BackendServices setSecurityPolicy
    • BackendServices list (gcloud only)

Users with the Security Admin role (roles/iam.securityAdmin) and the Compute Network Admin role can view Google Cloud Armor security policies by using the SecurityPolicies API methods get, list, and getRule.

Set up IAM permissions for custom roles

The following table lists the IAM roles' base permissions and their associated API methods.

IAM permission API methods
compute.securityPolicies.create SecurityPolicies insert
compute.securityPolicies.delete SecurityPolicies delete
compute.securityPolicies.get SecurityPolicies get
SecurityPolicies getRule
compute.securityPolicies.list SecurityPolicies list
compute.securityPolicies.use BackendServices setSecurityPolicy
compute.securityPolicies.update SecurityPolicies patch
SecurityPolicies addRule
SecurityPolicies patchRule
SecurityPolicies removeRule
compute.backendServices.setSecurityPolicy BackendServices setSecurityPolicy

Rules for rate-based throttling

Rules for rate-based throttling have the following format in the Google Cloud CLI:

gcloud compute security-policies rules create PRIORITY \
    --security-policy=SECURITY_POLICY \
    {--expression=EXPRESSION | --src-ip-ranges=SRC_IP_RANGE} \
    --action "throttle" \
    --rate-limit-threshold-count=RATE_LIMIT_THRESHOLD_COUNT \
    --rate-limit-threshold-interval-sec=RATE_LIMIT_THRESHOLD_INTERVAL_SEC \
    --conform-action=[allow] \
    --exceed-action=[deny-403|deny-404|deny-429|deny-502|redirect] \
    --exceed-redirect-type=[google-recaptcha|external-302] \
    --exceed-redirect-target=REDIRECT_URL \
    --enforce-on-key=[IP | ALL | HTTP-HEADER | XFF-IP | HTTP-COOKIE | HTTP-PATH | SNI | REGION-CODE] \
    --enforce-on-key-name=[HTTP_HEADER_NAME|HTTP_COOKIE_NAME]

Rate limiting on single keys

For example, the following gcloud CLI command creates a throttle rule at priority 105 with a rate limit of 100 requests each 60 seconds for each IP address in 1.2.3.0/24. Requests that exceed the throttling limit return a 429 error code.

gcloud compute security-policies rules create 105 \
    --security-policy SECURITY_POLICY \
    --src-ip-ranges="1.2.3.0/24" \
    --action=throttle \
    --rate-limit-threshold-count=100 \
    --rate-limit-threshold-interval-sec=60 \
    --conform-action=allow \
    --exceed-action=deny-429 \
    --enforce-on-key=IP

For example, the following gcloud CLI command creates a throttle rule at priority 110 with a rate limit of 10 requests each 60 seconds for each unique value of the HTTP header User-Agent across all requests coming from IP addresses in 1.2.3.0/24. Requests that exceed the throttling limit return a 429 error code.

gcloud compute security-policies rules create 110 \
    --security-policy SECURITY_POLICY \
    --src-ip-ranges="1.2.3.0/24" \
    --action=throttle \
    --rate-limit-threshold-count=10 \
    --rate-limit-threshold-interval-sec=60 \
    --conform-action=allow \
    --exceed-action=deny-429 \
    --enforce-on-key=HTTP-HEADER \
    --enforce-on-key-name='User-Agent'

Finally, you can issue rate-based bans for users who have a valid reCAPTCHA exemption cookie. For example, the following gcloud CLI command creates a throttle rule at priority 115 with a rate limit of 20 requests per 5 minutes for each unique reCAPTCHA exemption cookie across all requests that have a valid reCAPTCHA exemption cookie. Requests that exceed the throttling limit are redirected for reCAPTCHA Enterprise assessment. For more information about exemption cookies and reCAPTCHA Enterprise assessment, see the bot management overview.

gcloud compute security-policies rules create 115 \
    --security-policy SECURITY_POLICY \
    --expression="token.recaptcha_exemption.valid" \
    --action=throttle \
    --rate-limit-threshold-count=20 \
    --rate-limit-threshold-interval-sec=300 \
    --conform-action=allow \
    --exceed-action=redirect \
    --exceed-redirect-type=google-recaptcha \
    --enforce-on-key=HTTP-COOKIE \
    --enforce-on-key-name="recaptcha-ca-e"

Rate limiting based on JA3 fingerprints

You can use JA3 fingerprints as a rate limiting key. The following example creates a throttle rule at priority 1000 with a rate limit of 20 requests per 5 minutes that matches on requests with the /login path, based on the client's JA3 fingerprint. Requests that exceed the throttling limit are denied.

gcloud compute security-policies rules create 1000 \
    --security-policy SECURITY_POLICY \
    --expression "request.path.matches('/login')" \
    --action throttle \
    --rate-limit-threshold-count 20 \
    --rate-limit-threshold-interval-sec 300 \
    --conform-action allow \
    --exceed-action deny-429 \
    --enforce-on-key-configs tls-ja3-fingerprint

Rate limiting based on user IP address

When you receive requests that come through an upstream proxy, you can apply rate limiting based on the originating client's IP address. The following example creates a throttle rule at priority 1000 with a rate limit of 20 requests per 5 minutes that matches on requests with the /login path, based on the originating client's IP address. Requests that exceed the throttling limit are denied.

gcloud compute security-policies rules create 1000 \
    --security-policy SECURITY_POLICY
    --expression "request.path.matches('/login')"
    --action throttle
    --rate-limit-threshold-count 20
    --rate-limit-threshold-interval-sec 300
    --conform-action allow
    --exceed-action deny-429
    --enforce-on-key-configs user-ip

For more information about user IP address support, see the rules language reference.

Rate limiting based on multiple keys

You can also throttle traffic based on multiple rate limiting keys by using the enforce-on-key-configs flag. This flag replaces both the enforce-on-key flag and the enforce-on-key-name flag. The enforce-on-key-configs flag requires a comma-separated list of KEY=NAME pairs; although, you don't need to provide a name for some keys.

The following example creates a throttle rule for the policy POLICY_NAME at priority 105 with a rate limit of 100 requests each 60 seconds for each combination of HTTP-PATH and site_id across all requests coming from IP addresses in 1.2.3.0/24. Requests that exceed the throttling limit return a 429 error code.

gcloud compute security-policies rules create 105 \
    --security-policy=POLICY_NAME \
    --src-ip-ranges="1.2.3.0/24" \
    --action=throttle \
    --rate-limit-threshold-count=100 \
    --rate-limit-threshold-interval-sec=60 \
    --conform-action=allow \
    --exceed-action=deny-429 \
    --enforce-on-key-configs="HTTP-PATH,HTTP-COOKIE=site_id"

Rules for rate-based bans

Rules for rate-based bans have the following format in the gcloud CLI:

gcloud compute security-policies rules create PRIORITY \
    --security-policy=SECURITY_POLICY \
    {--expression=EXPRESSION | --src-ip-ranges=SRC_IP_RANGE} \
    --action "rate-based-ban" \
    --rate-limit-threshold-count=RATE_LIMIT_THRESHOLD_COUNT \
    --rate-limit-threshold-interval-sec=RATE_LIMIT_THRESHOLD_INTERVAL_SEC \
    --ban-duration-sec=BAN_DURATION_SEC \
    --ban-threshold-count=BAN_THRESHOLD_COUNT \
    --ban-threshold-interval-sec=BAN_THRESHOLD_INTERVAL_SEC \
    --conform-action=[allow] \
    --exceed-action=[deny-403|deny-404|deny-429|deny-502|redirect] \
    --exceed-redirect-type=[google-recaptcha|external-302] \
    --exceed-redirect-target=REDIRECT_URL \
    --enforce-on-key=[IP | ALL | HTTP-HEADER | XFF-IP | HTTP-COOKIE | HTTP-PATH | SNI | REGION-CODE] \
    --enforce-on-key-name=[HTTP_HEADER_NAME|HTTP_COOKIE_NAME]

For example, the following gcloud CLI command creates a rate-based ban rule at priority 100 for each IP address whose requests match a header fish with value tuna and ban it for 300 seconds when its rate exceeds a limit of 50 requests for each 120 seconds. Banned requests return an error code of 404.

gcloud compute security-policies rules create 100 \
    --security-policy=sec-policy \
    --expression="request.headers['fish'] == 'tuna'" \
    --action=rate-based-ban \
    --rate-limit-threshold-count=50 \
    --rate-limit-threshold-interval-sec=120 \
    --ban-duration-sec=300 \
    --conform-action=allow \
    --exceed-action=deny-404 \
    --enforce-on-key=IP

For example, the following gcloud CLI command creates a rate-based ban rule at priority 101 to limit all requests whose region code matches US to 10 requests per 60 seconds. The rule also bans requests from the US region for 300 seconds when their rate exceeds a limit of 1000 requests per 600 seconds. Banned requests return an error code of 403.

gcloud compute security-policies rules create 101 \
    --security-policy sec-policy \
    --expression "origin.region_code == 'US'" \
    --action rate-based-ban \
    --rate-limit-threshold-count 10 \
    --rate-limit-threshold-interval-sec 60 \
    --ban-duration-sec 300 \
    --ban-threshold-count 1000 \
    --ban-threshold-interval-sec 600 \
    --conform-action allow \
    --exceed-action deny-403 \
    --enforce-on-key ALL

For example, the following gcloud CLI command creates a rate-based ban rule at priority 102 to limit all requests from any source IP address range to 20 requests per 60 seconds. The rule also bans requests from any source IP address range for 600 seconds when the rate of requests exceeds a limit of 500 requests per 400 seconds. Banned requests return an error code of 429.

gcloud compute security-policies rules create 102 \
    --security-policy sec-policy \
    --src-ip-ranges="*" \
    --action rate-based-ban \
    --rate-limit-threshold-count 20 \
    --rate-limit-threshold-interval-sec 60 \
    --ban-duration-sec 600 \
    --ban-threshold-count 500 \
    --ban-threshold-interval-sec 400 \
    --conform-action allow \
    --exceed-action deny-429 \
    --enforce-on-key ALL

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