github.com/rkt/rkt@v1.30.1-0.20200224141603-171c416fac02/Documentation/install-rkt-in-coreos.md (about)

     1  # Installing a different version of rkt in CoreOS Container Linux
     2  
     3  If a different version of rkt is required than what ships with CoreOS Container Linux, a
     4  oneshot systemd unit can be used to download and install an alternate version
     5  on boot.
     6  
     7  The following unit will use curl to download rkt, its signature, and the CoreOS
     8  app signing key. The downloaded rkt is then verified with its signature, and
     9  extracted to /opt/rkt.
    10  
    11  ```
    12  [Unit]
    13  Description=rkt installer
    14  Requires=network.target
    15  
    16  [Service]
    17  Type=oneshot
    18  RemainAfterExit=yes
    19  ExecStart=/usr/bin/mkdir -p /opt/rkt
    20  ExecStart=/usr/bin/curl --silent -L -o /opt/rkt.tar.gz <rkt-url>
    21  ExecStart=/usr/bin/curl --silent -L -o /opt/rkt.tar.gz.sig <rkt-sig-url>
    22  ExecStart=/usr/bin/curl --silent -L -o /opt/coreos-app-signing-key.gpg https://coreos.com/dist/pubkeys/app-signing-pubkey.gpg
    23  ExecStart=/usr/bin/gpg --keyring /tmp/gpg-keyring --no-default-keyring --import /opt/coreos-app-signing-key.gpg
    24  ExecStart=/usr/bin/gpg --keyring /tmp/gpg-keyring --no-default-keyring --verify /opt/rkt.tar.gz.sig /opt/rkt.tar.gz
    25  ExecStart=/usr/bin/tar --strip-components=1 -xf /opt/rkt.tar.gz -C /opt/rkt
    26  ```
    27  
    28  The URLs in this unit must be filled in before the unit is installed. Valid
    29  URLs can be found on [rkt's releases page][rkt-releases].
    30  
    31  This unit should be installed with either [ignition][ignition] or a [cloud config][cloud-config].
    32  Other units being added can then contain a `After=rkt-install.service` (or
    33  whatever the service was named) to delay their running until rkt has been
    34  installed.
    35  
    36  [rkt-releases]: https://github.com/rkt/rkt/releases
    37  [ignition]: https://coreos.com/ignition/docs/latest/
    38  [cloud-config]: https://coreos.com/os/docs/latest/cloud-config.html