macos - How to reinstall python@2 from Homebrew?

57
votes

I have been having issues with openssl and python@2 with brew, which have explained here (unresolved). The documented workaround to reinstall Python and openssl was not working, so I decided I would uninstall and reinstall Python.

The problem is, when you try to install Python 2 with brew, you receive this message:

brew install python@2
Error: No available formula with the name "python@2"
==> Searching for a previously deleted formula (in the last month)...
Warning: homebrew/core is shallow clone. To get complete history run:
  git -C "$(brew --repo homebrew/core)" fetch --unshallow

python@2 was deleted from homebrew/core in commit 028f11f9e:
  python@2: delete (https://github.com/Homebrew/homebrew-core/issues/49796)
  EOL 1 January 2020.
  We gave it 1 month more to live so that people had time to migrate.
  All in all, developers had 11 years to do their migration.
  You can use the `brew extract` command and maintain python@2 in your own
  tap if necessary:
  https://docs.brew.sh/How-to-Create-and-Maintain-a-Tap

To show the formula before removal run:
  git -C "$(brew --repo homebrew/core)" show 028f11f9e^:Formula/[email protected]

If you still use this formula consider creating your own tap:
  https://docs.brew.sh/How-to-Create-and-Maintain-a-Tap

Unfortunately I still have a number of brew formulas that depend on Brew's python@2. Those include awscli, letsencrypt, pr sshuttle for example

aws
zsh: /usr/local/bin/aws: bad interpreter: /usr/local/opt/python@2/bin/python2.7: no such file or directory

I don't know how to use this brew extract command they documented to reinstall Python@2. It needs a formula and a tap. I imagine the formula would be python@2. I'm not sure what the tap would need to be.

Additionally reinstalling the taps such as aws or letsencrypt is not working very well either.

After reinstalling awscli (brew reinstall awscli), running aws commands still gives errors.

aws
/usr/local/Cellar/awscli/2.0.0/libexec/lib/python3.8/site-packages/jmespath/visitor.py:32: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if x is 0 or x is 1:
/usr/local/Cellar/awscli/2.0.0/libexec/lib/python3.8/site-packages/jmespath/visitor.py:32: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if x is 0 or x is 1:
/usr/local/Cellar/awscli/2.0.0/libexec/lib/python3.8/site-packages/jmespath/visitor.py:34: SyntaxWarning: "is" with a literal. Did you mean "=="?
  elif y is 0 or y is 1:
/usr/local/Cellar/awscli/2.0.0/libexec/lib/python3.8/site-packages/jmespath/visitor.py:34: SyntaxWarning: "is" with a literal. Did you mean "=="?
  elif y is 0 or y is 1:
/usr/local/Cellar/awscli/2.0.0/libexec/lib/python3.8/site-packages/jmespath/visitor.py:260: SyntaxWarning: "is" with a literal. Did you mean "=="?
  if original_result is 0:
usage: aws [options] <command> <subcommand> [<subcommand> ...] [parameters]
To see help text, you can run:

  aws help
  aws <command> help
  aws <command> <subcommand> help
aws: error: the following arguments are required: command
6
pythonmacoshomebrewpython-2.x

6 Answers

158
votes

It seems that the homebrew staff really makes it as hard as possible to use Python 2.7 on macOS as they can.

  1. The linked brew extract link is really not helpful, you need to look for answers here about how to make your own tap from extracted sources.
  2. The linked commit: 028f11f9e is wrong, as it contains the already deleted file.
  3. The brew extract command doesn't even work correctly, because of the @ in the package name.

The solution is very simple though, you just need to download the latest known commit and install from that file:

cd ~
wget https://raw.githubusercontent.com/Homebrew/homebrew-core/86a44a0a552c673a05f11018459c9f5faae3becc/Formula/[email protected]
brew install [email protected]
rm [email protected]

There might be a warning about this being "unstable", which I don't understand as a commit in a Git history is as stable as you can get.

48
votes

How to install python@2 from a local tap

The following method works with the current version (c9b8a3ef6) of brew:

$ brew tap-new <user>/homebrew-python2
$ brew extract python@2 <user>/homebrew-python2
$ brew install /usr/local/Homebrew/Library/Taps/<user>/homebrew-python2/Formula/[email protected]

The brew tap-new command creates a new local tap template in /usr/local/Homebrew/Library/Taps/<user>/homebrew-python2. The tap name needs a <user> and a <repo> component separated by a /. The actual values are arbitrary. The naming above follows the conventions from How to Create and Maintain a Tap. If you wanted to push the tap to GitHub you would use your GitHub username as user. Pushing to GitHub is not necessary (and was not performed in the instructions above).

The brew extract commands extracts the recent version of formula from the repos history into the given (local) tap. In our case [email protected] is extracted.

The brew install command finally installs the formula.

Why is this necessary?

The method discussed above (installing an old version of the formula from a GitHub commit URL) does not work anymore for python@2 with the current version of brew (c9b8a3ef6), it produces the following error:

$ brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/86a44a0a552c673a05f11018459c9f5faae3becc/Formula/[email protected]
Updating Homebrew...
==> Auto-updated Homebrew!
Updated Homebrew from 88f17b8b6 to c9b8a3ef6.
...
Error: Calling Installation of python@2 from a GitHub commit URL is disabled! Use 'brew extract python@2' to stable tap on GitHub instead.
11
votes

Please check following command (I am using it on macOS 10.13, it is possible that for a newer macOS it will work without source compilation):

brew install pr0d1r2/python2/[email protected] --build-from-source
5
votes

You can use pyenv to install python with:

brew install pyenv
pyenv install 2.7.18

Optionally set it to your global default:

pyenv global 2.7.18

Nice article on why using pyenv is better than using brew to manage your python installation.

2
votes

For posterity, working on macOS 10.15 (May/2021):

/usr/local/bin/brew tap-new ${USER}/homebrew-python2

/usr/local/bin/brew extract python@2 ${USER}/homebrew-python2

/usr/local/bin/brew install /usr/local/Homebrew/Library/Taps/${USER}/homebrew-python2/Formula/[email protected]

# https://github.com/Homebrew/brew/issues/5734#issuecomment-464705002
/usr/local/bin/brew untap ${USER}/python2
0
votes

I used methods from this page to install Python 2.7 on Mac for a year. But May 2021 I tried most suggestions on this page and they all failed.

Maybe Python 2.7 is getting harder to install or maybe my new macOS Big Sur 11.4 is causing the problem.

I was able to setup a working Python 2.7 environment in this way by reusing the native Python 2.7.16

  • Install pip manually
  • Setup a virtual environment
  • Install dependencies with pip in virtual environment

Here are the install steps:

wget https://bootstrap.pypa.io/pip/2.7/get-pip.py
python get-pip.py
pip install virtualenv
~/Library/Python/2.7/bin/pip  install virtualenv
virtualenv --python=/usr/bin/python venv
source venv/bin/activate