[docker] Can't run Curl command inside my Docker Container

I created a docker container from my OS X VM Docker host. I created it using the run command and created the container based off the ubuntu:xenial image off docker hub.

I'm now connected to my container after it's created and logged in as root and at the command prompt inside my container.

I tried to install homebrew and for some reason, I can't run the command to install Homebrew:

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

when I run that I get a bash:

curl: command not found

Not sure why I'm not able to use curl here inside my container.

You don't need to install curl to download the file into Docker container, use ADD command, e.g.

ADD https://raw.githubusercontent.com/Homebrew/install/master/install /tmp
RUN ruby -e /tmp/install

^{Note: Add above lines to your Dockerfile file.}

Another example which installs Azure CLI:

ADD https://aka.ms/InstallAzureCLIDeb /tmp
RUN bash /tmp/InstallAzureCLIDeb

So I added curl AFTER my docker container was running.

(This was for debugging the container...I did not need a permanent addition)

I ran my image

docker run -d -p 8899:8080 my-image:latest

(the above makes my "app" available on my machine on port 8899) (not important to this question)

Then I listed and created terminal into the running container.

docker ps
docker exec -it my-container-id-here /bin/sh

If the exec command above does not work, check this SOF article:

Error: Cannot Start Container: stat /bin/sh: no such file or directory"

then I ran:

apk

just to prove it existed in the running container, then i ran:

apk add curl

and got the below:

apk add curl

fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/main/x86_64/APKINDEX.tar.gz

fetch http://dl-cdn.alpinelinux.org/alpine/v3.8/community/x86_64/APKINDEX.tar.gz

(1/5) Installing ca-certificates (20171114-r3)

(2/5) Installing nghttp2-libs (1.32.0-r0)

(3/5) Installing libssh2 (1.8.0-r3)

(4/5) Installing libcurl (7.61.1-r1)

(5/5) Installing curl (7.61.1-r1)

Executing busybox-1.28.4-r2.trigger

Executing ca-certificates-20171114-r3.trigger

OK: 18 MiB in 35 packages

then i ran curl:

/ # curl
curl: try 'curl --help' or 'curl --manual' for more information
/ # 

Note, to get "out" of the drilled-in-terminal-window, I had to open a new terminal window and stop the running container:

docker ps
docker stop my-container-id-here

APPEND:

If you don't have "apk" (which depends on which base image you are using), then try to use "another" installer. From other answers here, you can try:

apt-get -qq update

apt-get -qq -y install curl

If you are using an Alpine based image, you have to

RUN
... \
apk add --no-cache curl \
curl ...
...

Ran into this same issue while using the CURL command inside my Dockerfile. As Gilles pointed out, we have to install curl first. These are the commands to be added in the 'Dockerfile'.

FROM ubuntu:16.04

# Install prerequisites
RUN apt-get update && apt-get install -y \
curl
CMD /bin/bash

This is happening because there is no package cache in the image, you need to run:

apt-get -qq update

before installing packages, and if your command is in a Dockerfile, you'll then need:

apt-get -qq -y install curl

After that install ZSH and GIT Core:

apt-get install zsh
apt-get install git-core

Getting zsh to work in ubuntu is weird since sh does not understand the source command. So, you do this to install zsh:

wget https://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh -O - | zsh

and then you change your shell to zsh:

chsh -s `which zsh`

and then restart:

sudo shutdown -r 0

This problem is explained in depth in this issue.