How to pass Basic authntication headers to backend server via API Manager

First let me explain how authorization headers work in API Manager. When user send authorization header along with API request we will use it for API authentication purpose. And we will drop it from out going message.
If you want to pass clients auth headers to back end server without dropping them at gateway you can enable following parameter and disable it.
Update following property in /repository/conf/api-manager.xml and restart server.

false

Then it will not drop user sent authorization headers at gateway. So whatever user send will go to back end as well

Send API request with Basic Auth header.

Incoming message to API gateway. As you can see we do not use API Manager authentication here. For this we can set resource auth type as none when we create API. Then send Basic auth header that need to pass back end server.
[2015-02-27 18:08:05,010] DEBUG - wire >> "GET /test-sanjeewa1/1.0.0 HTTP/1.1[\r][\n]"
[2015-02-27 18:08:05,011] DEBUG - wire >> "User-Agent: curl/7.32.0[\r][\n]"
[2015-02-27 18:08:05,011] DEBUG - wire >> "Host: 10.100.1.65:8280[\r][\n]"
[2015-02-27 18:08:05,011] DEBUG - wire >> "Accept: */*[\r][\n]"
[2015-02-27 18:08:05,011] DEBUG - wire >> "Authorization: Basic 2690b6dd2af649782bf9221fa6188[\r][\n]"
[2015-02-27 18:08:05,011] DEBUG - wire >> "[\r][\n]"

Out going message from gateway. You can see client sent Basic auth header is present in out going message
[2015-02-27 18:08:05,024] DEBUG - wire << "GET http://localhost/apim1/ HTTP/1.1[\r][\n]"
[2015-02-27 18:08:05,025] DEBUG - wire << "Authorization: Basic 2690b6dd2af649782bf9221fa6188[\r][\n]"
[2015-02-27 18:08:05,025] DEBUG - wire << "Accept: */*[\r][\n]"
[2015-02-27 18:08:05,025] DEBUG - wire << "Host: localhost:80[\r][\n]"
[2015-02-27 18:08:05,025] DEBUG - wire << "Connection: Keep-Alive[\r][\n]"
[2015-02-27 18:08:05,026] DEBUG - wire << "User-Agent: Synapse-PT-HttpComponents-NIO[\r][\n]"
[2015-02-27 18:08:05,026] DEBUG - wire << "[\r][\n]"


Other possible option is setting Basic auth headers at API gateway. For this we have 2 options.

01. Define Basic auth headers in API when you create API(see attached image). 

In API implement phase you can provide required basic auth details. Then API manager gateway will send provided authorization details as basic oauth headers to back end. Here we can let client to send Bearer token authorization header with API request. And gateway will drop it(after Bearer token validation) and pass Basic auth header to back end.

Incoming message to API gateway. Here user send Bearer token to gateway. Then gateway validate it and drop from out message.
[2015-02-27 17:36:15,580] DEBUG - wire >> "GET /test-sanjeewa/1.0.0 HTTP/1.1[\r][\n]"
[2015-02-27 17:36:15,595] DEBUG - wire >> "User-Agent: curl/7.32.0[\r][\n]"
[2015-02-27 17:36:15,595] DEBUG - wire >> "Host: 10.100.1.65:8280[\r][\n]"
[2015-02-27 17:36:15,595] DEBUG - wire >> "Accept: */*[\r][\n]"
[2015-02-27 17:36:15,595] DEBUG - wire >> "Authorization: Bearer 2690b6dd2af649782bf9221fa6188-[\r][\n]"
[2015-02-27 17:36:15,595] DEBUG - wire >> "[\r][\n]"

Out going message from gateway. You can see Basic auth header added to out going message
[2015-02-27 17:36:20,523] DEBUG - wire << "GET http://localhost/apim1/ HTTP/1.1[\r][\n]"
[2015-02-27 17:36:20,539] DEBUG - wire << "Authorization: Basic YWRtaW46YWRtaW4=[\r][\n]"
[2015-02-27 17:36:20,539] DEBUG - wire << "Accept: */*[\r][\n]"
[2015-02-27 17:36:20,540] DEBUG - wire << "Host: localhost:80[\r][\n]"
[2015-02-27 17:36:20,540] DEBUG - wire << "Connection: Keep-Alive[\r][\n]"
[2015-02-27 17:36:20,540] DEBUG - wire << "User-Agent: Synapse-PT-HttpComponents-NIO[\r][\n]"


02. This is also same as previous sample. But if need you can set API resource authorization type as none. Then client don't need to send anything in request. But APIM will add Basic auth headers to outgoing message.
You can understand message flow and headers by looking following wire log 

Incoming message to API gateway
[2015-02-27 17:37:10,951] DEBUG - wire >> "GET /test-sanjeewa/1.0.0 HTTP/1.1[\r][\n]"
[2015-02-27 17:37:10,953] DEBUG - wire >> "User-Agent: curl/7.32.0[\r][\n]"
[2015-02-27 17:37:10,953] DEBUG - wire >> "Host: 10.100.1.65:8280[\r][\n]"
[2015-02-27 17:37:10,953] DEBUG - wire >> "Accept: */*[\r][\n]"
[2015-02-27 17:37:10,953] DEBUG - wire >> "[\r][\n]"

Out going message from gateway. You can see Basic auth header is present in out going message
[2015-02-27 17:37:13,766] DEBUG - wire << "GET http://localhost/apim1/ HTTP/1.1[\r][\n]"
[2015-02-27 17:37:13,766] DEBUG - wire << "Authorization: Basic YWRtaW46YWRtaW4=[\r][\n]"
[2015-02-27 17:37:13,766] DEBUG - wire << "Accept: */*[\r][\n]"
[2015-02-27 17:37:13,766] DEBUG - wire << "Host: localhost:80[\r][\n]"
[2015-02-27 17:37:13,766] DEBUG - wire << "Connection: Keep-Alive[\r][\n]"