Suricata

Suricata-Update requires python-yaml, which is not covered in the current source-code Suricata or Suricata-Update install documentation, though it seems to be handled automatically if using the apt-get install.

https://suricata.readthedocs.io/en/suricata-4.1.0/install.html#advanced-installation
https://suricata-update.readthedocs.io/en/latest/quickstart.html#install-suricata-update

p@comp:~$ pip install --upgrade suricata-update
Collecting suricata-update
  Downloading https://files.pythonhosted.org/packages/e9/90/8dd8bae2616cbb7fcf3723658ae2ee945a527d48c3d908be7e520192327d/suricata-update-1.0.0.tar.gz (59kB)
    100% |████████████████████████████████| 61kB 1.8MB/s
Building wheels for collected packages: suricata-update
  Running setup.py bdist_wheel for suricata-update ... done
  Stored in directory: /home/pass/.cache/pip/wheels/31/26/47/8370248acd32c5ffb775eb3f2999c1ef8c49b5ea4facbd4eac
Successfully built suricata-update
Installing collected packages: suricata-update
Successfully installed suricata-update
You are using pip version 8.1.1, however version 18.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
p@comp:~$ suricata-update
error: pyyaml is required

Seen under Ubuntu 16.04.5.