I’m working on a Django project where we use Amazon SQS as broker for Celery. When you install the
celery[sqs] bundle (currently version 4.1.0) with
pip, it will also install the latest version of PycURL which Kombu uses for communicating over HTTP.
On my fresh install of macOS however, starting the Celery worker would raise the following error:
Which is weird, since there were no errors when I installed
Digging a little bit deeper in a Python shell reveals that PycURL wasn’t installed correctly:
>>> import pycurl Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: pycurl: libcurl link-time ssl backend (openssl) is different from compile-time ssl backend (none/other)
After some searching, it turns out that Apple stopped including OpenSSL headers since OS X 10.11 El Capitan.
To fix this, we first need to install OpenSSL via Homebrew:
Brew warns against symlinking it to
/usr/local to prevent issues with the system OpenSSL, so let’s not do that:
This formula is keg-only, which means it was not symlinked into /usr/local, because Apple has deprecated use of OpenSSL in favor of its own TLS and crypto libraries. If you need to have this software first in your PATH run: echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.bash_profile For compilers to find this software you may need to set: LDFLAGS: -L/usr/local/opt/openssl/lib CPPFLAGS: -I/usr/local/opt/openssl/include
In order for PycURL to find the OpenSSL headers, we need to tell
setup.py which SSL backend to use and where OpenSSL can be found:
You should have a working PycURL installation on macOS now!