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If you perform a request from within a TeamCity build, consider using system.for a limited set of build-related operations (like downloading artifacts) you can use values of teamcity.auth.userId/system.teamcity.auth.password system properties as credentials (within TeamCity settings you can reference them as %system.teamcity.auth.userId% and %system.teamcity.auth.password%).
The server URl is available as %teamcity.serverUrl% within a build.
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