How to install Flask on Python3 using pip?

Question

I want to try using Flask with Python3. I've got Python 3.4 on Ubuntu 14.04, which supposedly ships with pip included. So I tried

pip3 install flask

this ends in:

Cleaning up...
Command /usr/bin/python3 -c "import setuptools, tokenize;__file__='/tmp/pip_build_kramer65/flask/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /tmp/pip-i98xjzea-record/install-record.txt --single-version-externally-managed --compile failed with error code 1 in /tmp/pip_build_kramer65/flask
Storing debug log for failure in /tmp/tmpqc3b2nu5

So I tried importing it, but to no avail:

kramer65@vps1:~/cxs$ python3
Python 3.4.0 (default, Apr 11 2014, 13:05:11)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import flask
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named 'flask'

I can of course download it and install using sudo python3 setup.py install it that way, but I would rather do it "the standard way" so that things are easily and more standard to setup on production machines.

Does anybody know how I can import Flask with Python3 and pip? All tips are welcome!

Error log is available in http://pastebin.com/hd6LyVFP

Answer 1

You seem to have a permission issue. From the log you pasted to pastebin:

error: could not create '/usr/local/lib/python3.4/dist-packages/flask': Permission denied

This is because pip will attempt to install the package globally unless you specify a certain installation location. If you want to install this globally you must use sudo or install as a user with privileges.

Try the following:

sudo pip3 install flask

Or specify to a certain dir:

pip install -t <path> flask

However, with the latter method you will have to always inject the path to sys.modules so I suggest you just use sudo if you can.

Or even more preferrably, use virtualenv . Virtualenv allows you to very easily package your application for production because you can install only the packages you need and you've thus got automatic package isolation. Generating a requirements.txt is then as simple as pip freeze > requirements.txt . Remeber that if you end using a virtualenv, you must not use sudo to install packages as they will then be installed outside the virtualenv.

Answer 2

对于Python 3.6.4版本，可以通过执行以下操作来安装Flask：

sudo pip3.6 install flask