Setting up an APT repository is a reasonable way to distribute .deb packages to end users. You will want to create a signed repository, so that users can perform automated updates of your software (e.g. using apt-get install -y).

There are two kinds of repositories, "official" and "trivial". Trivial repositories are easier to set up than the official variety, but setup of signed trivial repositories is not well-documented. Here are instructions on how to set up your own repo:

Prerequisites:

• A .deb file, unsigned
• A machine with gpg installed
• RSA gpg keys created using gpg --gen-key

The repository is a simply a directory hierarchy. It can be local (e.g. on a usb stick) or published to a web server. Here is what it should look like when we are done:

- apt-repo/
    - foo.deb
    - Packages
    - Release
    - Release.gpg

Start by creating the hierarchy above with empty directories. Place foo.deb in the apt-repo directory, and then follow these instructions to create the signed files:

#sign the .deb file
cd apt-repo
dpkg-sig --sign builder foo.deb
cd ..

#create the Packages.gz file
cd apt-repo
apt-ftparchive packages . > Packages
cd ..

#create the Release file
apt-ftparchive release apt-repo > apt-repo/Release

#create a detached ascii signature of the Release file
gpg --armor --sign --detach-sign apt-repo/Release.gpg apt-repo/Release

Now you can upload the apt-repo directory to a webserver. If the repo path is http://example.com/foo/apt-repo, then end users will have to add a file named my-repo.list to the /etc/apt/sources.list.d directory that contains this line:

deb http://example.com/foo/apt-repo /

You now need to distribute your public key to end users, who will need to add it to their apt keychain. To export the public key to a text file:

gpg --armor --export foo@example.com --output foo-public-key

Then upload foo-public-key to a webserver. End users can install the key like so:

curl http://example.com/foo-public-key | sudo apt-key add -

Once the key has been added, end users can install your software using apt:

sudo apt-get update
sudo apt-get install foo