I’ve been looking at several MQTT brokers recently, and whilst I shan’t go into all the details of that, I shall post my hard-earned learnings on how to get VerneMQ built and running on macOS 10.12. This is all cobbled together from Googling various issues I ran into and bludgeoning my way to success, but hopefully this end to end description will be useful to somebody. To be honest, I have been massively put off VerneMQ because of this poor out-of-box developer experience and the extremely limited documentation.

Building

  • Ensure XCode and its command line tools are installed, because we’ll need the command line compiler tools.
  • VerneMQ is built on Erlang, so we need to install that. Unfortunately the official “Erlang Installer” for mac didn’t work, giving an error: “erl could not be removed”. Thankfully brew works nicely. Don’t know why I didn’t try that straight off.
    • If you haven’t already got brew, install it from https://brew.sh. It’s really very quick and simple and a must-have tool anyway. Then install Erlang:
      > brew install erlang
  • Get the VerneMQ code:
    > git clone git://github.com/erlio/vernemq.git vernemq_git
    > cd vernemq_git
  • The build would fail with “vmq_passwd.c:32:10: fatal error: ‘openssl/evp.h’ file not found”, on macOS 10.11+, so we need to specify openssl location in CFLAGS. Ensure openssl is installed first if necessary, with brew:
    > brew install openssl
  • Get past an erlang rebar bug, caused by files being readonly, by making them readable (bit of a hacky workaround):
    > chmod -R u+w /usr/local/Cellar/erlang
  • Actually build it, now we have everything we need, adapting the path here as necessary to match the openssl version you actually have.
    > CFLAGS="-I /usr/local/Cellar/openssl/1.0.2k/include -L/usr/local/Cellar/openssl/1.0.2k/lib" make rel
  • If that succeeded (after a fair while) you should have the binaries in _build/default/rel/vernemq/bin/

Running

It’s trivial to start the binary with default config:

_build/default/rel/vernemq/bin/vernemq start

Note that this starts it up then quits, but leaves the server running. You can do the same but with ‘stop’ to shut it down. See the docs on further things you can do with the vernemq binary.

Configuration

If you’ve just built it and are running from the _build location, the config file it is using is at _build/default/rel/vernemq/etc/vernemq.conf

I turned on anonymous users and added a websockets listener by following the instructions in that file. I restarted the server (vernemq restart) and then was able to successfully publish and subscribe with the handy HiveMQ online WebSocket MQTT client.

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