Connection pool settings for HTTP

Connection pools are typically set up for apps that must be accessed frequently, such as a web service. Without connection pools, every request to the web service requires a new connection to be opened. This setup might work if the web service is accessed occasionally. However, as clients scale and more requests are sent to the web service, opening a connection for each requests can get very expensive and easily overload the web service.

To prevent the web service from being overloaded, you can use the following connection pool settings:

• Maximum number of requests
• Maximum number of requests per connection
• Maximum number of retries
• Maximum number of pending requests

For more information, see the following resources.

• Gloo connection policy API docs

Before you begin

1. Complete the multicluster getting started guide to set up the following testing environment.
   • Three clusters along with environment variables for the clusters and their Kubernetes contexts.
   • The Gloo Platform CLI, meshctl, along with other CLI tools such as kubectl and istioctl.
   • The Gloo management server in the management cluster, and the Gloo agents in the workload clusters.
   • Istio installed in the workload clusters.
   • A simple Gloo workspace setup.
2. Install Bookinfo and other sample apps.

Configure connection policies for HTTP destinations

You can apply a connection policy at the destination level. For more information, see Applying policies.

The following example applies HTTP connection pool settings to all virtual destinations in the bookinfo namespace.

apiVersion: resilience.policy.gloo.solo.io/v2
kind: ConnectionPolicy
metadata:
  annotations:
    cluster.solo.io/cluster: ""
  name: http-connect
  namespace: bookinfo
spec:
  applyToDestinations:
  - kind: VIRTUAL_DESTINATION
    selector: {}
  config:
    http:
      idleTimeout: 2s
      maxRequestsPerConnection: 1
      maxRetries: 1
      maxRequests: 500
      maxPendingRequests: 500

Review the following table to understand this configuration. For more information, see the API docs.

Verify connection policies

1. Create a virtual destination for the ratings app.

   kubectl apply --context $REMOTE_CONTEXT1 -f- <<EOF
   apiVersion: networking.gloo.solo.io/v2
   kind: VirtualDestination
   metadata:
     name: ratings-global
     namespace: bookinfo
   spec:
     hosts:
     - ratings.global
     ports:
     - number: 80
       protocol: HTTP
       targetPort:
         name: http
     services:
     - labels:
         app: ratings
   EOF
   

2. Apply the example connection policy for the ratings app.

   kubectl apply --context $REMOTE_CONTEXT1 -f- <<EOF
   apiVersion: resilience.policy.gloo.solo.io/v2
   kind: ConnectionPolicy
   metadata:
     annotations:
       cluster.solo.io/cluster: ""
     name: http-connect
     namespace: bookinfo
   spec:
     applyToDestinations:
     - kind: VIRTUAL_DESTINATION
       selector: {}
     config:
       http:
         idleTimeout: 2s
         maxRequestsPerConnection: 1
         maxRetries: 1
         maxRequests: 500
         maxPendingRequests: 500
   EOF
   

3. Verify that an Istio destination rule is created for the virtual destination.

   kubectl get destinationrule --context $REMOTE_CONTEXT1 -n bookinfo
   

   Example output:

   NAME                                                              HOST             AGE
   ratings-global-virtual-destinat-2ab46384c8b40be3cfab9740ac8fb2c   ratings.global   11s
   

4. Describe the Istio destination rule.

   kubectl describe --context $REMOTE_CONTEXT1 -n bookinfo destinationrule <destination-rule>
   

   In the output, verify that the Connection Pool settings include the http settings that your policy configures.

   ...
   Traffic Policy:
    Port Level Settings:
      Connection Pool:
        Http:
          http1MaxPendingRequests:      500
          http2MaxRequests:             500
          Idle Timeout:                 2s
          Max Requests Per Connection:  1
          Max Retries:                  1
   

5. Optional: Clean up the resources that you created.

   kubectl -n bookinfo delete virtualdestination ratings-global --context $REMOTE_CONTEXT1
   kubectl -n bookinfo delete ConnectionPolicy http-connect --context $REMOTE_CONTEXT1