How do I install Python 3 on an AWS EC2 instance?

Note: This may be obsolete for current versions of Amazon Linux 2 since late 2018 (see comments), you can now directly install it via yum install python3.

In Amazon Linux 2, there isn't a python3[4-6] in the default yum repos, instead there's the Amazon Extras Library.

sudo amazon-linux-extras install python3

If you want to set up isolated virtual environments with it; using yum install'd virtualenv tools don't seem to reliably work.

virtualenv --python=python3 my_venv

Calling the venv module/tool is less finicky, and you could double check it's what you want/expect with python3 --version beforehand.

python3 -m venv my_venv

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Other things it can install (versions as of 18 Jan 18):

[ec2-user@x ~]$ amazon-linux-extras list
  0  ansible2   disabled  [ =2.4.2 ]
  1  emacs   disabled  [ =25.3 ]
  2  memcached1.5   disabled  [ =1.5.1 ]
  3  nginx1.12   disabled  [ =1.12.2 ]
  4  postgresql9.6   disabled  [ =9.6.6 ]
  5  python3=latest  enabled  [ =3.6.2 ]
  6  redis4.0   disabled  [ =4.0.5 ]
  7  R3.4   disabled  [ =3.4.3 ]
  8  rust1   disabled  [ =1.22.1 ]
  9  vim   disabled  [ =8.0 ]
 10  golang1.9   disabled  [ =1.9.2 ]
 11  ruby2.4   disabled  [ =2.4.2 ]
 12  nano   disabled  [ =2.9.1 ]
 13  php7.2   disabled  [ =7.2.0 ]
 14  lamp-mariadb10.2-php7.2   disabled  [ =10.2.10_7.2.0 ]

If you do a

sudo yum list | grep python3

you will see that while they don't have a "python3" package, they do have a "python34" package, or a more recent release, such as "python36". Installing it is as easy as:

sudo yum install python34 python34-pip