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 Throttle resources through rate limits

Rate limiting in OpenStack Object Storage is implemented as a pluggable middleware that you configure on the proxy server. Rate limiting is performed on requests that result in database writes to the account and container SQLite databases. It uses memcached and is dependent on the proxy servers having highly synchronized time. The rate limits are limited by the accuracy of the proxy server clocks.

 Configure rate limiting

All configuration is optional. If no account or container limits are provided, no rate limiting occurs. Available configuration options include:

Table 9.67. Description of configuration options for [filter-ratelimit] in proxy-server.conf
Configuration option = Default value Description
account_blacklist = c,d Comma separated lists of account names that will not be allowed. Returns a 497 response. r: for containers of size x, limit requests per second to r. Will limit PUT, DELETE, and POST requests to /a/c/o. container_listing_ratelimit_x = r: for containers of size x, limit listing requests per second to r. Will limit GET requests to /a/c.
account_ratelimit = 0 If set, will limit PUT and DELETE requests to /account_name/container_name. Number is in requests per second.
account_whitelist = a,b Comma separated lists of account names that will not be rate limited.
clock_accuracy = 1000 Represents how accurate the proxy servers' system clocks are with each other. 1000 means that all the proxies' clock are accurate to each other within 1 millisecond. No ratelimit should be higher than the clock accuracy.
container_listing_ratelimit_0 = 100 No help text available for this option.
container_listing_ratelimit_10 = 50 No help text available for this option.
container_listing_ratelimit_50 = 20 No help text available for this option.
container_ratelimit_0 = 100 No help text available for this option.
container_ratelimit_10 = 50 No help text available for this option.
container_ratelimit_50 = 20 No help text available for this option.
log_sleep_time_seconds = 0 To allow visibility into rate limiting set this value > 0 and all sleeps greater than the number will be logged.
max_sleep_time_seconds = 60 App will immediately return a 498 response if the necessary sleep time ever exceeds the given max_sleep_time_seconds.
rate_buffer_seconds = 5 Number of seconds the rate counter can drop and be allowed to catch up (at a faster than listed rate). A larger number will result in larger spikes in rate but better average accuracy.
set log_address = /dev/log Location where syslog sends the logs to
set log_facility = LOG_LOCAL0 Syslog log facility
set log_headers = false If True, log headers in each request
set log_level = INFO Log level
set log_name = ratelimit Label to use when logging
use = egg:swift#ratelimit Entry point of paste.deploy in the server
with container_limit_x = r No help text available for this option.

The container rate limits are linearly interpolated from the values given. A sample container rate limiting could be:

container_ratelimit_100 = 100

container_ratelimit_200 = 50

container_ratelimit_500 = 20

This would result in:

Table 9.68. Values for Rate Limiting with Sample Configuration Settings
Container Size Rate Limit
0-99 No limiting
100 100
150 75
500 20
1000 20
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