Add install script for 'curl | bash' style installation

[codyaray]

@confluentinc/caas

We can also support OS-agnostic curl some.url | bash style installs for the CLI. It downloads the tarball to a temp directory, verifies the checksums, and then installs in ./bin by default.

This works today, assuming you have api.github.com in your ~/.netrc since our CLI is private.

curl -ns https://api.github.com/repos/confluentinc/cli/contents/install.sh?ref=master -H Accept:application/vnd.github.raw | bash

(Note: change ref=master to ref=curl-bash until this is merged.)

You can install somewhere other than ./bin, for example in /usr/local/bin:

curl -ns https://api.github.com/repos/confluentinc/cli/contents/install.sh?ref=master -H Accept:application/vnd.github.raw | sudo bash -s -- -b /usr/local/bin

Once our CLI is public, then we can shorten this down to

curl -s https://raw.githubusercontent.com/confluentinc/cli/master/install.sh | bash

Which of course means we can use a short link:

curl -s https://git.io/confluent-cli | bash

using something like this: https://blog.github.com/2011-11-10-git-io-github-url-shortener/

Since our cli repo is still private, I had to use a forked godownloader.
PR to merge back upstream: goreleaser/godownloader#78.

./godownloader --repo confluentinc/cli > install.sh 

[chicagobuss]

very nice

[codyaray]

@cyrusv You can now install with this:

curl -sL https://git.io/vhuDX | bash

It'll install in ./bin. You'll still have to make sure that ./bin is added to your $PATH.

You can also install directly to /usr/local/bin by running:

curl -sL https://git.io/vhuDX | sudo bash -s -- -b /usr/local/bin

We can create a nicer short link later when we the repo is open sourced. (A lot of link shorteners, including git.io, don't allow you to the change the underlying URL later. So don't mess it up.)

For this to work, you'll need to setup your ~/.netrc with

machine api.github.com
        login yourusername
        password yourpasswordorpersonalaccesstoken

where the personal access token has the repo permission.