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Managing costs

By Kong Inc.

Managing costs

The following configuration example targets a GraphQL endpoint at our SWAPI playground.

See the Costs API reference for more information.

Add a GraphQL service and route

curl -X POST http://localhost:8001/services \
  --data "name=example" \
  --data "host=httpbin.konghq.com" \
  --data "port=443" \
  --data "protocol=https"
curl -X POST http://localhost:8001/services/example/routes \
  --data "hosts=example.com"

Enable the plugin on the service

Example using a single time window:

curl -i -X POST http://localhost:8001/services/example/plugins \
  --data name=graphql-rate-limiting-advanced \
  --data config.limit=100 \
  --data config.window_size=60 \
  --data config.sync_rate=10

Example using multiple time windows:

curl -i -X POST --url http://localhost:8001/services/example/plugins \
  --data 'name=graphql-rate-limiting-advanced' \
  --data 'config.window_size[]=60' \
  --data 'config.window_size[]=3600' \
  --data 'config.limit[]=10' \
  --data 'config.limit[]=100' \
  --data 'config.sync_rate=10'

Changing the default strategy

curl -X POST http://localhost:8001/services/example/plugins \
  --data name=graphql-rate-limiting-advanced \
  --data config.limit=100 \
  --data config.limit=10000 \
  --data config.window_size=60 \
  --data config.window_size=3600 \
  --data config.sync_rate=10 \
  --data config.cost_strategy=default

curl -i -X PATCH http://localhost:8001/plugins/{plugin_id} \
  --data config.cost_strategy=node_quantifier

Limit query cost by using config.max_cost

It’s usually a good idea to define a maximum cost applied to any query, regardless if the call is within the rate limits for a consumer.

By defining a max_cost on our service, we are ensuring no query will run with a cost higher than our set max_cost. By default it’s set to 0, which means no limit.

curl -X POST http://localhost:8001/services/example/plugins \
  --data name=graphql-rate-limiting-advanced \
  --data config.limit=100 \
  --data config.limit=10000 \
  --data config.window_size=60 \
  --data config.window_size=3600 \
  --data config.sync_rate=0 \
  --data config.max_cost=5000

To update max_cost:

curl -X PATCH http://localhost:8001/plugins/{plugin_id} \
  --data config.max_cost=10000

Using config.score_factor to modify costs

GraphQL query cost depends on multiple factors based on our resolvers and the implementation of the schema. Cost on queries, depending on the cost strategy might turn very high when using quantifiers, or very low with no quantifiers at all. By using config.score_factor the cost can be divided or multiplied to a certain order of magnitude.

For example, a score_factor of 0.01 will divide the costs by 100, meaning every cost unit represents 100 nodes.

curl -X POST http://localhost:8001/services/example/plugins \
  --data name=graphql-rate-limiting-advanced \
  --data config.limit=100 \
  --data config.limit=10000 \
  --data config.window_size=60 \
  --data config.window_size=3600 \
  --data config.sync_rate=0 \
  --data config.max_cost=5000 \
  --data config.score_factor=0.01

To update score_factor:

curl -i -X PATCH http://localhost:8001/plugins/{plugin_id} \
  --data config.score_factor=1