Downloading Images¶

To download images with Tako, the image distributor should have provided you with two things:

• A remote url, such as https://images.example.com/app-foo.
• A public key, such as l0D28J2fiIXvWPbeZP7wkaq+dB55Gl2ysigl9mQH29k=.

The next step is to create a configuration file to tell Tako what to fetch from that remote, and where to store it. For example, write the following to example.tako:

Origin=https://images.example.com/app-foo
PublicKey=l0D28J2fiIXvWPbeZP7wkaq+dB55Gl2ysigl9mQH29k=
Destination=/tmp/app-foo
Version=*

Download the latest available image with tako fetch example.tako. Now /tmp/app-foo/latest is a symlink to the latest image, which itself is stored as a readonly file in /tmp/app-foo/store.

Local Store¶

Tako downloads images into a destination directory. It creates the following files there:

store/<hexdigest>  # Readonly raw image files.
manifest           # A copy of the manifest served by the origin.
latest             # Symlink to the latest image.

The store keeps older versions to allow quick rollbacks. In the future Tako will be able to prune older versions if the store exceeds a certain size.

Automating Updates¶

To use Tako to keep the image up to date, run Tako periodically, for example using a systemd timer. Using RandomizedDelaySec= is recommended to avoid overloading the remote server.

Initial Provisioning¶

Tako can be used to acquire an initial image. For example, you can run tako fetch through ExecStartPre= with systemd. In this case, downloading the latest manifest and possibly downloading a new image, may incur an unacceptable startup delay. In this case the --init flag can be used to skip network access if a valid manifest and image already exist.