nox > Command pip install --upgrade -e contrib/opencensus-ext-postgresql failed with exit code 1:
DEPRECATION: Python 2.7 will reach the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 won't be maintained after that date. A future version of pip will drop support for Python 2.7.
Obtaining file:///root/repo/contrib/opencensus-ext-postgresql
Requirement already satisfied, skipping upgrade: opencensus<1.0.0,>=0.4.dev0 in /root/repo (from opencensus-ext-postgresql==0.2.dev0) (0.4.dev0)
Collecting psycopg2>=2.7.3.1 (from opencensus-ext-postgresql==0.2.dev0)
  Downloading https://files.pythonhosted.org/packages/c7/ca/75236b17f1b951950ffc55d657c5aa408d3d0327a1b6c4c0f7cb16ef7e7b/psycopg2-2.8.tar.gz (367kB)
    Complete output from command python setup.py egg_info:
    running egg_info
    creating pip-egg-info/psycopg2.egg-info
    writing pip-egg-info/psycopg2.egg-info/PKG-INFO
    writing top-level names to pip-egg-info/psycopg2.egg-info/top_level.txt
    writing dependency_links to pip-egg-info/psycopg2.egg-info/dependency_links.txt
    writing manifest file 'pip-egg-info/psycopg2.egg-info/SOURCES.txt'
    
    Error: pg_config executable not found.
    
    pg_config is required to build psycopg2 from source.  Please add the directory
    containing pg_config to the $PATH or specify the full executable path with the
    option:
    
        python setup.py build_ext --pg-config /path/to/pg_config build ...
    
    or with the pg_config option in 'setup.cfg'.
    
    If you prefer to avoid building psycopg2 from source, please install the PyPI
    'psycopg2-binary' package instead.
    
    For further information please check the 'doc/src/install.rst' file (also at
    <http://initd.org/psycopg/docs/install.html>).