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 set up 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 connection pool settings to determine the maximum number of connections that can be opened to your app and the maximum number of requests that can be sent per connection.

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

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
   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:
          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