[HTTPCLIENT-2315] Inconsistent observance of system properties when using HttpClients.createSystem

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 5.3
• Fix Version/s: 5.3.1, 5.4-alpha2
• Component/s: HttpClient (classic)
• Assignee: Unassigned
• Reporter: Vitor Dantas
• Created: 05/Jan/24 18:54
• Updated: 08/Jan/24 14:35
• Resolved: 08/Jan/24 14:35

Description

During the startup of my application, I configure an SSLContext with additional certificates and set it as a global default using SSLContext.setDefault. Subsequently, all requests created without explicit configuration can successfully connect to servers requiring these certificates. This setup functions seamlessly with various APIs I currently utilize:

• java.net.URLConnection (e.g., URLConnection conn = url.openConnection())
• java.net.http.HttpClient (e.g., HttpClient client = HttpClient.newHttpClient())
• org.springframework.ws.client.core.WebServiceTemplate (e.g., WebServiceTemplate webServiceTemplate = new WebServiceTemplate())

Previously, this approach worked flawlessly with org.apache.httpcomponents:httpclient:4.5.14, where clients were created using:
HttpClient httpclient = org.apache.http.impl.client.HttpClients.createSystem();

However, issues arise (due to missing certificates) after upgrading to org.apache.httpcomponents.client5:httpclient5:5.3 and creating clients with:
HttpClient httpclient = org.apache.hc.client5.http.impl.classic.HttpClients.createSystem();

When creating a client with HttpClientBuilder.create().useSystemProperties().build() or more succinctly with HttpClients.createSystem(), the expectation is that system properties are observed throughout.

However, upon inspecting the code, it becomes evident that the connection manager underneath is created using PoolingHttpClientConnectionManagerBuilder.create().build(), and not PoolingHttpClientConnectionManagerBuilder.create().useSystemProperties().build() as one might anticipate.

Consequently, an internal condition registers the HTTPS socketFactory using SSLConnectionSocketFactory.getSocketFactory() instead of SSLConnectionSocketFactory.getSystemSocketFactory(). This, in turn, results in the creation of a new SSLContext.getInstance(SSLContextBuilder.TLS) instead of leveraging the default one through SSLSocketFactory.getDefault().

Why is this the case? Is it possible to change this behavior so that the configuration is simplified when one aims to use the default socket factory? Specifically, without the need for explicit configuration of the connection manager in such a common scenario.