Configuring keep alive timeout on Message Processors

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This document explains how to configure the keep alive timeout for the Apigee Edge Message Processors.

The keep alive timeout on the Message Processor allows a single TCP connection to send and receive multiple HTTP requests/responses from/to the backend server, instead of opening a new connection for every request/response pair.

The default value of the keep alive timeout property on the Message Processor is 60 seconds. This timeout period is applicable to the backend servers configured in the target endpoint configuration and in the ServiceCallout policy of your API proxy.

The keep alive timeout for Message Processors can be increased or decreased from the default value of 60 seconds based on your needs. It can be configured in the following ways:

In the API proxy
- In the target endpoint
- In the ServiceCallout policy
On the Message Processor

The following properties control the keep alive timeout on the Message Processors:

Property name Location Description

Property name	Location	Description
`keepalive.timeout.millis`	API proxy: Target endpoint `ServiceCallout` policy	This is the maximum idle time for which the Message Processor allows a single TCP connection to send and receive multiple HTTP requests/responses, instead of opening a new connection for every request/response pair. By default, this property takes the value set for the `HTTPClient.keepalive.timeout.millis` property on the Message Processor, where the default value is `60` seconds. If this property is modified with a new timeout value for the target server used in the target endpoint or the `ServiceCallout` policy in the specific API proxy, then the keep alive time only for that specific target server is affected.
`HTTPClient.keepalive.timeout.millis`	Message Processor	This is the maximum idle time for which the Message Processor allows a single TCP connection to send and receive multiple HTTP requests/responses, instead of opening a new connection for every request/response pair. This property is used for all the API proxies running on this Message Processor. The default value of this property is `60` seconds. You can either modify this property as explained in Configuring keep alive timeout on Message Processors below, or you can overwrite this value by setting the `keepalive.timeout.millis`property at the API proxy level.

keepalive.timeout.millis

API proxy:

Target endpoint
ServiceCallout policy

This is the maximum idle time for which the Message Processor allows a single TCP connection to send and receive multiple HTTP requests/responses, instead of opening a new connection for every request/response pair.

By default, this property takes the value set for the HTTPClient.keepalive.timeout.millis property on the Message Processor, where the default value is 60 seconds.

If this property is modified with a new timeout value for the target server used in the target endpoint or the ServiceCallout policy in the specific API proxy, then the keep alive time only for that specific target server is affected.

HTTPClient.keepalive.timeout.millis

Message Processor

This property is used for all the API proxies running on this Message Processor.

The default value of this property is 60 seconds.

You can either modify this property as explained in Configuring keep alive timeout on Message Processors below, or you can overwrite this value by setting the keepalive.timeout.millisproperty at the API proxy level.

Before you begin

Before you use the steps in this document, be sure you understand the following topics:

If you aren’t familiar with keep alive timeout, see the keepalive.timeout.millis property description in TargetEndpoint Transport Property Specification.
If you aren’t familiar with configuring properties for Edge on Private Cloud, read How to configure Edge.

Configuring keep alive timeout in API proxy

The keep alive timeout can be configured in the API proxy in the following places:

Target endpoint
ServiceCallout policy

Configuring keep alive timeout in target endpoint of API proxy

This section explains how to configure keep alive timeout in the target endpoint of your API proxy. The keep alive timeout can be configured through the property keepalive.timeout.millis, which represents the keep alive timeout value in milliseconds.

Note: Configuring the keep alive timeout in the target endpoint of your API proxy overrides the default value (60 seconds) with the new value and affects only the specific API proxy where it is configured. The rest of the API Proxies continue to use the default keep alive timeout value of 60 seconds.

In the Edge UI, select the specific API proxy in which you would like to configure the new keep alive timeout value.
Select the specific target endpoint that you want to modify.

Add the property keepalive.timeout.millis with an appropriate value under the <HTTPTargetConnection> element in the TargetEndpoint configuration.

For example, to change the keep alive Timeout to 30 seconds, add the following block of code:

<Properties>
  <Property name="keepalive.timeout.millis">30000</Property>
</Properties>

Since the keepalive.timeout.millis property is in milliseconds, the value for 30 seconds is 30000.

The following examples show how to configure the keep alive timeout in the target endpoint configuration of your API proxy:

Example target endpoint configuration using URL for backend server

<TargetEndpoint name="default">
  <HTTPTargetConnection>
    <URL>https://mocktarget.apigee.net/json</URL>
    <Properties>
      <Property name="keepalive.timeout.millis">30000</Property>
    </Properties>
  </HTTPTargetConnection>
</TargetEndpoint>

Example target endpoint configuration using target server

<TargetEndpoint name="default">
  <HTTPTargetConnection>
    <LoadBalancer>
      <Server name="target1" />
      <Server name="target2" />
    </LoadBalancer>
    <Properties>
      <Property name="keepalive.timeout.millis">30000</Property>
    </Properties>
    <Path>/test</Path>
  </HTTPTargetConnection>
</TargetEndpoint>

Save the changes made to your API proxy.

Configuring keep alive timeout in ServiceCallout policy of API proxy

This section explains how to configure the keep alive timeout in the ServiceCallout policy of your API proxy. The keep alive timeout can be configured through the keepalive.timeout.millis property, which represents the keep alive timeout value in milliseconds.

Note: Configuring the keep alive timeout in the ServiceCallout policy of the API proxy overrides the default value (60 seconds) with the new value and affects only the specific ServiceCallout policy where it is configured. The rest of the ServiceCallout policies and API Proxies continue to use the default keep alive timeout value of 60 seconds.

Required permissions: To perform this task, you must have edit access permissions to the specific API proxy in which you would like to configure the keep alive timeout for the ServiceCallout policy.

To configure the keep alive timeout in the ServiceCallout policy using the keepalive.timeout.millis property:

In the Edge UI, select the specific API proxy in which you would like to configure the new keep alive timeout value for the ServiceCallout policy.
Select the specific ServiceCallout policy that you want to modify.

Add the property keepalive.timeout.millis with an appropriate value under the <HTTPTargetConnection> element in the TargetEndpoint configuration.

For example to change the keep alive timeout to 30 seconds, add the following block of code:

<Properties>
  <Property name="keepalive.timeout.millis">30000</Property>
</Properties>

Since the keepalive.timeout.millis property is in milliseconds, the value for 30 seconds is 30000.

The following examples show how to configure the keep alive timeout in the ServiceCallout policy of your API proxy:

Example ServiceCallout policy configuration using URL for backend server

<ServiceCallout name="Service-Callout-1">
  <DisplayName>Service Callout-1</DisplayName>
  <HTTPTargetConnection>
    <Properties>
      <Property name="keepalive.timeout.millis">30000</Property>
    </Properties>
    <URL>https://mocktarget.apigee.net/json</URL>
  </HTTPTargetConnection>
</ServiceCallout>

Example ServiceCallout policy configuration using target server

<ServiceCallout enabled="true" name="Service-Callout-1">
  <DisplayName>Service Callout-1</DisplayName>
  <Response>calloutResponse</Response>
  <HTTPTargetConnection>
    <LoadBalancer>
      <Server name="target1" />
      <Server name="target2" />
    </LoadBalancer>
    <Properties>
      <Property name="keepalive.timeout.millis">30000</Property>
    </Properties>
    <Path>/test</Path>
  </HTTPTargetConnection>
</ServiceCallout>

Save the changes made to your API proxy.

Configuring keep alive timeout on Message Processors

This section explains how to configure the keep alive timeout on the Message Processors. The keep alive timeout can be configured through the property HTTPClient.keepalive.timeout.millis, which represents the keep alive timeout value in milliseconds on the Message Processor component. Since this property is commented on the Message Processor, you need to use the special syntax conf/http.properties+HTTPClient.keepalive.timeout.millis as described in the section Set a token that is currently commented out in How to configure Edge.

To configure the keep alive timeout on the Message Processors, do the following:

On the Message Processor machine, open the following file in an editor. If it does not already exist, then create it.
```
/opt/apigee/customer/application/message-processor.properties
```
For example, to open the file using vi, enter the following:
```
vi /opt/apigee/customer/application/message-processor.properties
```
Add a line in the following format to the properties file, substituting a value for TIME_IN_MILLISECONDS:
```
conf/http.properties+HTTPClient.keepalive.timeout.millis=TIME_IN_MILLISECONDS
```
For example, to change the keep alive timeout on the Message Processor to 30 seconds, add the following line:
```
conf/http.properties+HTTPClient.keepalive.timeout.millis=30000
```
Save your changes.

Ensure the properties file is owned by the apigee user as shown below:

chown apigee:apigee /opt/apigee/customer/application/message-processor.properties

Restart the Message Processor as shown below:

/opt/apigee/apigee-service/bin/apigee-service edge-message-processor restart

If you have more than one Message Processor, repeat the above steps on all the Message Processors.

Verifying keep alive timeout on Message Processors

This section explains how to verify that the keep alive timeout has been successfully modified on the Message Processors.

Even though you use the special syntax conf/http.properties+HTTPClient.keepalive.timeout.millis to set the keep alive timeout on the Message processor, you need to verify if the actual property HTTPClient.keepalive.timeout.millis has been set with the new value.

On the Message Processor machine, search for the property HTTPClient.keepalive.timeout.millis in the /opt/apigee/edge-message-processor/conf directory and check to see if it has been set with the new value as shown below:
```
grep -ri "HTTPClient.keepalive.timeout.millis" /opt/apigee/edge-message-processor/conf
```
If the new keep alive timeout value is successfully set on the Message Processor, then the above command shows the new value in the http.properties file.

The sample result from the above command after you have configured keep alive timeout to 30 seconds is as follows:
```
/opt/apigee/edge-message-processor/conf/http.properties:HTTPClient.keepalive.timeout.millis=30000
```
In the example output above, notice that the property HTTPClient.keepalive.timeout.millis has been set with the new value 30000 in http.properties. This indicates that the keep alive timeout is successfully configured to 30 seconds on the Message Processor.
If you still see the old value for the property HTTPClient.keepalive.timeout.millis, then verify that you have followed all the steps outlined in Configuring keep alive timeout on Message Processors correctly. If you have missed any step, repeat all the steps again correctly.
If you are still not able to modify the keep alive timeout, then contact Google Cloud Apigee Edge Support.