archiveAug 15, 2020

Fixing Python locale errors in Docker Ubuntu

How to clear locale.Error: unsupported locale setting in an Ubuntu Docker container so pip install works again.

Fixing Python locale errors in Docker Ubuntu

Check the error

root@2d1e0b4d517a:/etc/default# cat /etc/issue
Ubuntu 16.04.7 LTS \n \l

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3/namin.py", line 4112, in setlocale
    return _setlocale(categories, locale)
locale.Error: unsupported locale setting

On some Ubuntu Docker images, pip install fails with locale.Error: unsupported locale setting. That usually means the container's locale config is incomplete.

Inspect locale state

$ locale
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
LANG=en_US.UTF-8
LANGUAGE=
LC_CTYPE=UTF-8
LC_NUMERIC="en_US.UTF-8"
LC_TIME="en_US.UTF-8"
LC_COLLATE="en_US.UTF-8"
LC_MONETARY="en_US.UTF-8"
LC_MESSAGES="en_US.UTF-8"
LC_PAPER="en_US.UTF-8"
LC_NAME="en_US.UTF-8"
LC_ADDRESS="en_US.UTF-8"
LC_TELEPHONE="en_US.UTF-8"
LC_MEASUREMENT="en_US.UTF-8"
LC_IDENTIFICATION="en_US.UTF-8"
LC_ALL=
 
$ locale -a
locale: Cannot set LC_CTYPE to default locale: No such file or directory
C
C.UTF-8
en_US.utf8
POSIX

If locale -a complains that files are missing, set the environment up first:

/usr/sbin/dpkg-reconfigure: locales is not installed
 
# echo "LC_ALL=en_US.UTF-8" | tee -a /etc/environment
LC_ALL=en_US.UTF-8
 
# echo "en_US.UTF-8 UTF-8" | tee -a /etc/locale.gen
en_US.UTF-8 UTF-8
 
# echo "LANG=en_US.UTF-8" | tee -a /etc/locale.conf
LANG=en_US.UTF-8

Reconfigure locales

# dpkg-reconfigure locales

Select en_US.UTF-8 UTF-8, then set the default to en_US.UTF-8.

After that, pip install should work again.