问题
I'm using an image nginx which is based on dockerfile/ubuntu. On attaching to the docker container's shell
docker exec -it <container_id> /bin/bash
I want to do a git pull so I tried installing git but apt is unable to find the package:
root@a71e45d5cd40:/# apt-get install git
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package git
How can we install git from that image and why is it missing?
cat /etc/apt/sources.list
deb http://httpredir.debian.org/debian wheezy main
deb http://httpredir.debian.org/debian wheezy-updates main
deb http://security.debian.org wheezy/updates main
deb http://nginx.org/packages/mainline/debian/ wheezy nginx
cat /etc/apt/sources.list.d/*
cat: /etc/apt/sources.list.d/*: No such file or directory
apt-cache madison git
N: Unable to locate package git
回答1:
This is happening because the apt repository is not yet updated, it is common practice to clean your apt repositories and tmp files after creating an image, which your base image is probably doing.
To fix this, you are going to want to run apt-get update prior to installing git, it is good practice to combine the update and install command at the same time to bust cache on the update if the install line changes:
RUN apt-get update && apt-get install -y git
Using -y is convenient to automatically answer yes to all the questions.
来源：https://stackoverflow.com/questions/29929534/docker-error-unable-to-locate-package-git