Ubuntu – Run sudo command with non-root user in Docker container

I have this Dockerfile:

FROM ubuntu:17.04

# Must have packages
RUN apt-get update && apt-get install -y nano zsh curl git

# Instal Oh my Zsh
RUN bash -c "$(curl -fsSL https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh)"
RUN sed -i -- 's/robbyrussell/sonicradish/g' /root/.zshrc 

# Add none root user
RUN adduser admin
USER admin

I'm connecting with the admin user with the zsh shell.

docker exec -ti linux zsh

I'm adding a non-root user (admin).

I still want to execute a sudo command with this user, but it errors out:

$ sudo apt-get install vim
zsh: command not found: sudo

Same message with bash shell.

How can I run sudo commands with a non-root user?

When I don't use sudo I get a permission error:

$ apt-get install vim
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?