Without changing code, how to force httpClient to use proxy by environment variables or JVM arguments

Question

I found these system settings http.proxyHost and http.proxyPort are of no use to httpClient. How to force the httpClient to use proxy by environment variables or VM arguments or something like those without changing code?

Newspaperman

Have you found a workaround for this question? I am facing the same issue, a third party library (azure-keyvault-java-sdk) uses its own httpClient and I am unable to force it to use a proxy. The actual http calls are made in new Executor threads which does not allow me to set the ProxySelector in the calling thread as well. Any solutions? – Yolandayolande

We have the same issue, we want to do this without a code change where even a configuration change is considered a code change since we need to issue a new deployment to do so. Our conclusion is that it is not possible to override the client's configuration with JVM command line options, you just have to make a change to the client's configuration and issue a new release. – Hamo

Answer 1

HTTP client (v 4.5.1 for my case) can use system proxy like this:

HttpClient httpClient = HttpClientBuilder.create().useSystemProperties().build();
//or 
HttpClient httpClient = HttpClients.createSystem();

Optics

Exactly, you can use the system properties like this. Do not forget that for connection to https://... urls you have to use https.proxyHost etc properties. A similar issue with details answer from my side: #30630830 – Manfred

Answer 2

in https://issues.apache.org/jira/browse/HTTPCLIENT-1128

SystemDefaultHttpClient was added to ver. 4.2

see http://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/impl/client/SystemDefaultHttpClient.html

Touched

As @Optics noted below, you can also use .useSystemProperties() before calling .build() on any HttpClientBuilder to read system properties such as http.proxyHost and http.proxyPort: hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/… – Rubenrubens

Answer 3

you can force proxy to HttpClient by yourself with client.getHostConfiguration().setProxy(host, port) method. I usually create wrapper class around HttpClient and when initializing this class I setup proxy from whatever source (env. variables ...).

I used java.net.ProxySelector.setDefault(new MyProxySelector()) in situation where you can't set proxy directly on HttpClient. You have to implement your own ProxySelector class and method select makes proxy selection based on requested URI. You can make url->proxy mapping to configure particular URI address to required proxy or return one proxy for all requested URI globally.

As I can see in HttpClient source code, there's no other way how to configure proxy only setProxy method. I'm using commons-httpclient-3.1.

Elijah

@Newspaperman Can you create wrapper class around HttpClient and initialize it always by your way? – Elijah

say, I have a 3rd party library, it uses httpclient inside to get something. How to dela with this situation? – Newspaperman

In this case I used java.net.ProxySelector.setDefault(new MyProxySelector());. You have to implement your own ProxySelector class and method select makes proxy selection based on requested URI (Make url<->proxy mapping to configure particular URL address to required proxy ). As I can see in HttpClient source code, there's no other way how to configure proxy even setProxy method. I'm using commons-httpclient-3.1. – Elijah

Answer 4

AFAIK, you can't manage this without code changes but you can get closer to native behaviour by using your own connection manager. See ProxySelector changes URL's scheme from https:// to socket://

Qatar

Answer 5

Does this help?

System.setProperty("https.proxyHost", proxy_host);
System.setProperty("http.proxyHost", proxy_host);
System.setProperty("https.proxyPort", proxy_port);
System.setProperty("http.proxyPort", proxy_port);

Or ofcourse you can pass the same properties via the commandline

Athanasian

Unfortunately this does not work for httpclient, this is my question – Newspaperman

The question clearly states that those variables were not working. – Clostridium