gistfile1.md

Easy one line Chef installation for all platforms (except windows)

curl https://www.opscode.com/chef/install.sh | sudo bash

That's it. This can be put in any instructions, such as a README or someone's blog, since the logic is in the shell script. Provided you download the script using https, the file has standard levels of authentication and encryption protecting it from manipulation.

This is obviously a shell script, if you're really concerned about the argument that it may contain nefarious activities within, you can easily review it before you run it.

wget https://www.opscode.com/chef/install.sh 
less install.sh
sudo bash install.sh

More complex alternatives

Without a shell script, you must have a website that selects the correct installation procedure based on platform, platform version, and architecture, because you cannot provide a single binary package that is correct for all of them. Source installs require extensive configuration of a development environment and multiple dependencies.

See the old Chef 10 installation directions for specific examples of the complexity of supporting multiple platforms and versions this way.

Source install:

# multiple steps to install development dependencies, which all vary by platform
sudo apt-get install build-essential ruby ruby-dev rake 
# download the source
wget https://www.somewhere.com/chef/source.tgz
tar -xvzf source.tgz
cd source
rake gem
sudo gem install pkg/chef-*.gem

Binary install for a single platform:

wget https://www.somewhere.com/chef/install-ubuntu-12.04-x86.deb -O /tmp/install.deb
sudo dpkg -i /tmp/install.deb
# or
sudo yum install wget
wget https://www.somewhere.com/chef/install-centos-6-x86.rpm -O /tmp/install.rpm
sudo rpm -Uvh /tmp/install.rpm

But does being in a regular package make you trust it more than a shell script? Most distribution packages contain shell scripts that are run on installation, and they're harder to review than a simple shell script. The required commands differ depending on platform. For example:

dpkg -e /tmp/install.deb /tmp/install.conffiles
less /tmp/install.conffiles/postinst

What about dependencies? Does your platform have all the required dependencies? Are they new enough (no, unless you're on the most recent version). So now you also need to add a repository for all of these platforms to get updated dependencies. All of these are going to need to be backported and maintained for multiple versions by someone.