Connection pool settings for HTTP
Use a connection policy to configure connection pool settings for an HTTP destination.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.
If you import or export resources across workspaces, your policies might not apply. For more information, see Import and export policies.
Before you begin
- 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 askubectl
andistioctl
. - 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.
- 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 connection policy currently does not support selecting Gloo external services as a destination.
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.
Setting | Description |
---|---|
applyToDestinations |
Configure which destinations to apply the policy to, by using labels. Destinations can be a Kubernetes service, VirtualDestination, or ExternalService. If you do not specify any destinations or routes, the policy applies to all destinations in the workspace by default. If you do not specify any destinations but you do specify a route, the policy applies to the route but to no destinations. |
config |
Configure the connection settings to apply to the selected destinations. To set connection pool settings for HTTP destinations, use http as the protocol. For TCP connection pool settings, use tcp . The connection policy in this guide shows how to configure connection pool settings for an HTTP destination. To find an example for a TCP connection policy, see Connection pool settings for TCP. |
http.idleTimeout |
The time a connection can stay open without receiving any requests. By default, this value is set to 1 hour. If the idle time is reached, the connection is closed. |
http.maxRequestsPerConnection |
The maximum number of requests that can be sent to a destination per connection. If you set this value to 1, you disable keep alive. By default, this value is set to 0, which equals unlimited , and allows a maximum of 2^29 requests per connection. |
http.maxRetries |
The maximum number of retries that can be outstanding to all hosts in a cluster at a given time. Defaults to 2^32-1. |
Verify connection policies
-
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
-
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
-
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
-
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
-
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