The easiest way to adding ppa (Personal Package Archive) into ubuntu (and it’s variant) repository is to use add-apt-repository. Unfortunately this tool sometime is not installed in the system especially on minimalist distribution such as docker image. The good news is, we can add it manually.

Visit ppa to search witch ppa we want to add to our system. Use the search menu to find the ppa we want.

Search PPA

Open the page and click Technical details about this PPA to show ppa url and gpg key.

Technical details PPA

Open file /etc/apt/source.list and add the url we get from ppa page to the bottom of the file. in this example

# certbot source package to generate letsencrypt ssl certificate
deb xenial main
deb-src xenial main

Step 2 — Import GPG Key

Now we need to install gpg key. Back to ppa webpage, find the signing key that look like 4096R/75BCA694 (What is this?). Copy the portion after the slash but not including the help link; e.g. just 75BCA694.

Open the terminal and type this command

sudo apt-key adv --keyserver --recv-keys 75BCA694

Step 3 — Update package list

If gpg key successfully installed we can update our package list using command

sudo apt-get update

To install certbot package after ppa is added, we can use this command

sudo apt-get install certbot


Now we can adding ppa source package to our source list without using command add-apt-repository. All we need to do is add ppa ulr to source.list and import gpg key signed by ppa package maintainer.