We are trying to pass the basic authentication header when using the SCDF prebuilt processor "http-request" to call an external service. From my understanding, the message http headers are not automatically carried over in making the call, we need to populate the "headers-expression" property instead. The following is the the call processor step of the stream definition:
http-request --body-expression=payload
--url-expression='headers.reportURL' --http-method-expression='headers.httpMethod' --headers-expression='headers.Authorization'
We already had set the message header "Authorization" as "Basic <base64encoded("user:password")>" in previous step so "headers.Authorization" has the correct Basic Authentication header value when the message arrives to "http-request" processor. However, this doesn't work, the stream log has the following error:
org.springframework.expression.spel.SpelEvaluationException: EL1001E: Type conversion problem, cannot convert from java.lang.String to java.util.Map at org.springframework.expression.spel.support.StandardTypeConverter.convertValue(StandardTypeConverter.java:75) at org.springframework.expression.common.ExpressionUtils.convertTypedValue(ExpressionUtils.java:57)
From the error message, it appears we need to pass a map? Something like "Authorization : headers.Authorization"? (The stream wasn't even deployed successfully by coding this way). We don't want to hard-code the "headers.Authorization" as the literal Basic Auth base64 string. Also how to specify more than one header (like adding "content-type") in the "headers-expression"? We have searched the SCDF documentation and online but can't seem to find an example of how to do it.
Thanks.
If you say that you have already set those headers upfront, consider just that expression like this: --headers-expression='headers'. The headersproperty of theMessageis aMap` by itself.
If that still doesn't fit your requirements, consider to use an in-line map syntax for SpEL: https://docs.spring.io/spring-framework/docs/current/reference/html/core.html#expressions-inline-maps