`cwru_robotics_autoinstall_scripts` Package

This repository provides autoinstall files that automates Ubuntu/ROS installations for robots and workstations for CWRU Robotics researchers.

This package is still under development. These scripts are not well verified at this time.

Usage

As of Ubuntu 20.04, Ubuntu Server can use an auto-installation mechanism that includes being able to retrieve the installation configuration from the internet. Ubuntu Server can be converted into Ubuntu Desktop by installing the ubuntu-desktop package. More information about how to create and use the autoinstall capabilities of Ubuntu Server can be found on the Ubuntu website.

The bootloader could be either the graphical or the command line version of Grub2. The Linux kernel command line must be edited in either version to use the autoinstall script. The way to get to the place to edit the command line in the two Grub versions differs. There is no way to determine which will appear beforehand. When booting using the Ubuntu Server Live CD, hold the Shift key down. The bootloader menu should come up.

Graphical Grub
- Press F6, and escape. The kernel command line is available for editing.
Command Line Grub
- Select the basic installation item and press the "e" key.
- Find the line that ends in ---.

In either instance, there should be three dashes, ---. After the dashes add the following line:

autoinstall 'ds=nocloud-net;s=/cdrom/;h=<new_hostname>'

It is also possible to use an autoinstall script directly from the GitHub repository:

autoinstall 'ds=nocloud-net;s=https://cwru-robotics.github.io/cwru_robotics_autoinstall_scripts/<linux_name>/<install_type>/;h=<new_hostname>'

Failed Attempt

If the installation shows a menu to select the language for the installation, the autoinstallation has failed. Before trying again review the logs.

While the language selection option is still up, press CTRL+ALT+F2. This switches to a second virtual terminal and a command prompt should come up. Review the error log for the cloud-init autoinstallation with the following command: less /var/log/cloud-init.log. Look through the file for references to the meta-data file downloaded from the URL above. That file is downloaded first. If it is not there, the problem is with contacting the server holding the files (GitHub). If it is there, check just after it to verify that the user-data file was downloaded successfully. If they are both downloaded, that indicates the problem is with the user-data file. It would be unusual for meta-data to have downloaded successfully and user-data to have failed.

It may be necessary to review the syslog as well: less /var/log/syslog. The kernel command line parameters can be found in this file. Check to see that the autoinstall line shown above is complete and accurate in this file.

These logs can be placed on another computer using ssh/scp if there is a computer configured to accept ssh connections.

Set IP Address Manually

If an IP address has not been configured before the install script attempts to download the configuration file, the download will fail (a known bug in cloud-init exacerbated by the slow allocation of IP addresses by the CWRU network). It is possible to manually specify the IP address and other information at the kernel command line. It goes between the --- and the autoinstall ds=no....

ip=<ip_address>::<gateway>:<netmask>:<hostname>:<network_interface>:none:<dns>[:dns2]

For the Atlas# computers in the Glennan 210 Laboratory which have static IP addresses assigned, retrieve these values from the computer before attempting the installation. Either boot the computer like normal or boot into the live Ubuntu trial on the USB drive, then go to the Network Settings and write down IP addresses for the computer, gateway, netmask (generally 255.255.255.0), and at least one DNS server. For the Atlas# computers, the network interface is eno1.

Post-Installation

Clean-up is required after when manually specifying the IP address. Remove the GRUB_CMDLINE_LINUX entry in the /etc/default/grub file that contains the extended kernel command line that specifies the IP Address. The following command must be run after this file is saved.

sudo update-grub

Finally, the IP address may need to be reset if the Manual IP Address method was used above. The following commands should accomplish this:

cloud-init clean --logs

cloud-init init --local

cloud-init clean -r

The final command reboots the computer. It should be

Installations Types

There are three types of installations provided by this repository in this branch which is directed at Ubuntu Server 20.04 Focal Fossa and ROS Noetic Ninjemys. The naming is based on naming on the ROS installation packages. All three, however, include the installation of GIT. All installations all prevent root from being able to remotely login and have sshd activated.

The installation names are based on the ROS installation meta-packages defined in REP 150.

`ros-noetic-desktop-full`

This installation is intended for desktop computers with graphics. Ubuntu Server is a minimal, non GUI installation. This installation adds the ubuntu-desktop meta-package that functionally makes the installation the same as Ubuntu Desktop. The ROS ros-noetic-desktop-full meta-package is installed.

Snap is used to install the VS Code IDE.

`ros-noetic-perception`

The ros-noetic-perception installation meta-package is a "capability variant" ROS installation. ROS discourages to have graphics dependencies. It does have image manipulation packages, but no graphical outputs. It is intended for computers that are installed on robots that are not expected to have GUI and typically run "headless."

`ros-noetic-robot`

The ros-noetic-robot installation meta-package is prohibited from including graphics dependencies. It is intended for lower-level, embedded computers installed on robots.

Information on `autoinstall` using `cloud-config`

The autoinstall protocol is based on the cloud-config system. There are three possible files that are used by cloud-config to automate the installation process. Ubuntu provides documentation for autoinstall for Ubuntu Server (beginning with 20.04) is available. There is also documentation that provides higher level information for cloud-config.

`user-data`

This is the file that contains the most of the auto-installation information at this time. It is a YAML file. Use the Ubuntu reference to understand the structure of the file as it is used for installing Ubuntu (Server 20.04 and newer?).

The most basic file contains the identity tag that sets the hostname of the computer, the real name of the user, username, and the password "crypted". OpenSSL (openssl) can be used to generate a "crypted" password that can be used by the passwd file. This method of providing a password is secure since it is impossible to reconstruct a password from its HASH value. There are several cryptographic hash algorithms that can be used. The algorithm is indicated by the number in the second position of the resulting HASH. View the man page for OpenSSL to learn about the available algorithms and how they are used. The SHA512 algorithm is indicated by the -6 element.

openssl passwd -6 -salt 'FhcddHFVZ7ABA4Gi' ubuntu

This command should result in the HASH shown below.

$6$FhcddHFVZ7ABA4Gi$XOmu9O8SDaBexz6Zw0FCjeZJbwPP.OTK7TTZp8G/BydFXvlpHQxuuMHPzZ3IGgt3u5n73a1EkysSCendbXCDG1

The salt added to the command allows the output to be repeatable. (The salt algorithm is identified by the 6 and the salt is shown between the second and third $.) It is better to allow openssl to generate random salt each time it runs.

It has also become a standard procedure to not include the password on the command line as it can be viewed by any user through the process list. There are various ways to keep improve the security of entering the password. One way is to take the password on the STDIN. This is shown below.

openssl passwd -6 -stdin <<< ubuntu

The above command can be used to generate the cryptographic HASH of a password that can be included in a publicly available document. The password cannot be determined from the HASH. In this way, the username and password information in the automated installation script is still relatively secure and presents a minimal (but non-zero) security compromise.

The password(s) in this repository is not ubuntu and the actual password itself should not ever appear in the repository as that would present a significant security compromise.

The user-data file also adds the ROS repository to apt to allow it to be installed locally. It also configures sshd and adds the running of the ROS setup.bash to the /etc/bash.bashrc so any and all users will be automatically configured for using ROS.

There is a second way to specify users under a user-data key within the autoinstall key. (Yes, a user-data key within the user-data file.) This key actually passes the information off to cloud-init. Consult the cloud-init documentation for using that method. Keep in mind, however, to put both the username and passwd values in quotes. (Also note that there is some documentation on the internet that incorrectly shows an example using the key password for a password hash instead of passwd. That will not work.

`meta-data`is s

This file is empty at this time. It must be present in the system, however, in order for the automated installation to work. It can be and is empty in these installations.

`vendor-data`

This is also a file that is requested during the boot process. Unlike user-data and meta-data its absence will not cause an error. If present, it can be empty.

cwru-robotics/cwru_robotics_autoinstall_scripts

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