It has been found that the CAF_NET_EXPORT macro is not present in the prometheus class which results in linking error when attempting to create the server from the documentation shown here..

The following screen shot shows one proposed fix which seemed to resolve the linking issue.

Separately, and maybe related, the manual mentions here about using a configuration of "caf.middleman.prometheus-http.port" to enable the prometheus server. The first problem about this, is that it appears this configuration is now called "caf.net.prometheus-http.port" as I was able to find this the v1.0.2 codebase. However, despite configuring the middleman in this fashion the prometheus server does not actually seem to run as I experienced using the alternative method (see top of this issue). While my actor app was running I was able to see a server listening on my configured port using netstat -tuln, but did not get any response when doing curl http://localhost:8080/metrics . Finally, lines 63-85 of libcaf_net/caf/net/middleman.cpp seem to the naive user to be correct and I would have expected this to "just work" based on the code.