3. Server deployment guide

Deploying ttbd is not complicated; it can grow as large as you need it.

Bear in mind:

  • Only Fedora is supported at this point; other distros should work, but we do not have resources to support them.
  • Recent kernels are needed; when deployed in full force, ttbd puts a lot of stress on the USB bus and interfaces and it has uncovered bugs that are known to be fixed around Linux kernel > v4.5.
  • Follow these instructions as verbatim as possible. The fixtures described here have been designed to maximize reliability and minimize false positives or negatives.
  • There are security matters you should consider

3.1. Bill of materials

You will need the following depending on what hardware you plan to test

  • A Linux machine running Fedora >= v24 to run the ttbd server/s

    • plenty of USB ports
    • (optional) space to connect secondary USB cards to (rationale)
    • USB hubs, externally powered, to provide upstream connectivity to the server’s root USB ports
    • More than one network interface and network switches to interconnect the server with your power switches and targets (rationale)
  • Power control (to power targets up and down)

    (other power switches are possible, but drivers need to be written for them)

  • Miscelaneous cables (it is recommended to buy in bulk to avoid wasting time looking for them)

  • USB power bricks (2ma) at least (mostly for powering the YKUSH hubs)

  • USB serial terminal adaptors

  • MCU boards (Arduino101, Quark C1000, Quark D2000, FRDM k64f, etc)

It is recommended to get extra spare components, for quick replacement in case of failures.

3.2. Conventions

To execute a command as a normal user we’ll use:

$ command ...

to execute a comand as super-user (loging in as root or using sudo), we’ll use:

# command ...

Links will come in different flavours:

3.3. Server installation

Any Fedora system (version > 24) shall work out of the box with these instructions.

If you need proxy support, ensure it is properly setup.

3.4. Install and setup the TCF software

The software is available as RPM packages with all the dependencies (alternatively there are the not recommended manual installation steps).

# echo insecure > ~/.curlrc       # Don't mind the SSL certificate for RPM
# rpm -i https://RPMREPOHOST/repo/tcf-repo-v0-1-1.noarch.rpm
# dnf install -y --best --allowerasing ttbd-zephyr tcf-zephyr
# systemctl enable ttbd@production
# systemctl start ttbd@production


  • insecure tells the rpm -i command to bypass the HTTPS certificate check, as we might not have it yet in our certificate database.
  • --allowerasing is needed so conflicting packages (like ModemManager) are removed.
  • Replace -v0.11 with -master in the URL to get the development repository instead of the stable v0.11 tree.

The default configuration brings up an instance called production with a number of virtual networks, QEMU-based targets suitable for running the Zephyr OS on different architecture (qz*) and Cloud versions of Fedora Core (qlf*). Any local user can access.

Directories for the instance are /etc/ttbd-production for configuration, /var/run/ttbd-production for state and /var/cache/ttbd-production for temporary data.

From here you can (optional):

As well, you can add

3.4.1. Target networking

The default configuration in /etc/ttbd-production/conf_05_default.py is setup to create two IP networks for virtual (and physical) targets to intercomunicate with each other:

$ tcf list | grep nw
local/nwa                 # fc00::61:0/112
local/nwb                 # fc00::62:0/112

QEMU targets defined in the default configuration are made members of each subnetwork. The server host is always the .1 address.

Note that for for two targets to be able to do IP communication, the network target has to be powered-on before the targets.

More networks can be added by creating configuration files /etc/ttbd-production/conf_NAME.py containing:

    ttbl.tt.tt_power('nwd', vlan_pci()),
    tags = dict(
        ipv4_addr = '',
        ipv4_prefix_len = 24,

Be sure to not assign conflicting IP blocks, or IP blocks that route to the public internet or intranet–in the example the convention is followed to use network 192.168.X.0/24, where X is 61 for a in nwa, 62 for b in nwb, 63 for c in nwc, etc … following ASCII values and keeping network names short (otherwise system tools might start cutting them off).

The default configuration creates virtual networks for the virtual machines to communicate. It is possible to bridge a physical device by connecting it to the system and indicating so to the configuration. See conf_00_lib.vlan_pci for setup details, but it basically consists on:

  • connect a network interface to the server (USB or PCI); said network interface shall be connected to a network switch to which all the physical targets we want to interconnect are also connected

  • find the network interface’s MAC address (using something like ip link show)

  • add the tag mac_addr with said address to the network to which said interface is to be connected; for example the network nwc of the example:

        ttbl.tt.tt_power('nwc', vlan_pci()),
        tags = dict(
            mac_addr = "a0:ce:c8:00:18:73",
            ipv4_addr = '',
            ipv4_prefix_len = 24,

    or for an existing network (such as the configuration’s default nwa):

    # eth dongle mac 00:e0:4c:36:40:b8 is assigned to NWA
    ttbl.config.targets['nwa'].tags_update(dict(mac_addr = '00:e0:4c:36:40:b8'))
  • for each target that is connected to said network, report it as part of the network nwc:

    ttbl.config.targets['TARGETNAME-NN'].tags_update({ 'ipv4_addr': "" },
                                                     ic = 'nwc')
  • the network switch itself can be also power switched; if you connect it, for example to a Digital Loggers Web Power Switch 7 named spX on port N, you can can add


    thus, when powering up the network nwc, the last step will be to power up the network switch, and when powering it down, the first step done will be to power it off.

Be aware of the following when doing networking with TCF:

  • you can configure any number of targets to a TCF network, as long as you configure your IP space accordingly.

    Recommended space assignment (and the one followed by default) is:

    • .1: is the server
    • .2 - .10: Virtual Linux machines
    • .30 - .45: Virtual Zephyr machines
    • .100 - .254: Real HW targets

    likewise, target naming will go long ways on making it easy to identify which targets are in which networks. It is recommended to assign a number to each targets that matches the last nibble of their IP (v4/v6) address and append the letter of the network they are in, for example:

    • a101-32a: is an Arduino 101, IP in nwa
    • same70-54b: is in nwb
  • a network will own the physical network interface exclusively (in fact, it will even rename it)

  • a single testcase execution will use a network in an exclusive way, thus if your networks are composed of many independent targets, there might be low reutilization. You might be off creating smaller networks to improve paralellism.

    However, you can create targets Ta1, Ta2 and Ta3 from nwa in a testcase (including nwa) and target Ta4 (without netwokring) in another one. What cannot be shared is the nwa interconnect target.

  • a network switch can be shared amongst many networks, but this will introduce noise that can alter test results. Not recommended unless the switch can split LANs.

  • a test will try to run in many different ways in the same network

    For example, if your test allocates three targets A, B and C and there are seven T1-T7 available, it will try to run in different assignment permutations:

    A B C
    T1 T2 T3
    T1 T3 T2
    T2 T3 T1

    how the targets are picked depends on what the test is asking for, but TCF is trying to ensure maximum coverage, so it might pick up way more combinations than you expect. Use the mode paramater to tcfl.tc.target() in the testcase to indicate how each target shall be picked. Targets for which you have no interest in doing coverage shall be selected as mode=’any’, while the ones you want to make sure all types are covered shall be set as mode=’one-per-type’.

    Use the -P command line to limit how many permutations you want tcf run to go with.

3.4.2. Configure QEMU Zephyr OS targets

The default installation provies a list of QEMU-based targets that are suitable for Zephyr OS development; they are defined in /etc/ttbd-production/conf_07_zephyr.py (you can add more or less as you please modifying said file).

Now, tcf list should show, after you login:

# tcf list | grep ^qz

Output may vary based on configuration, but there targets called qz (for QEMU Zephyr), five for each supported architecture (x86, ARM, NiosII, RiscV32). Test cases may be run against these targets now as explained here, but in a nutshell, running as a local user (never root!!), we ask TCF to run the Hello World Zephyr OS sample in all the different available targets:

$ git clone http://github.com/zephyrproject-rtos/zephyr zephyr.git
$ cd zephyr.git
$ tcf run -v /usr/share/tcf/examples/test_zephyr_hello_world.py
PASS1/bfgv    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz32c-x86:x86: build passed
PASS1/r7rf    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz46a-riscv32:riscv32: build passed
PASS1/3opq    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz44b-nios2:nios2: build passed
PASS1/qyjy    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz36a-arm:arm: build passed
PASS1/bfgv    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz32c-x86:x86: evaluation passed
PASS1/qyjy    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz36a-arm:arm: evaluation passed
PASS1/r7rf    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz46a-riscv32:riscv32: evaluation passed
PASS1/3opq    /usr/share/tcf/examples/test_zephyr_hello_world.py#_test @local/qz44b-nios2:nios2: evaluation passed
PASS0/        toplevel @local: 4 tests (4 passed, 0 failed, 0 blocked, 0 skipped) - passed

Here it is saying that for each target, it built the test image and then ran the steps in the test script /usr/share/tcf/examples/test_zephyr_hello_world.py, that builds the Zephyr OS sample in samples/hello_world, all of them evaluating succesfully, so the ran was considered a sucess (PASS).

3.4.3. Configure QEMU targets

QEMU targets can be configured to boot a VM with

3.4.4. Configure physical test targets and power switches

Everything in ttbd is a test target; they need to be added by creating Python objects that represent them in the configuration files. Helper functions have been created to simplify the process.

Power switches are used to build power rails to power on or off the different test targets and other infrastructure components

Create a configuration file /etc/ttbd-production/conf_10_targets.py and start adding configuration statements as described in the links below:

MCU boards supported by default require different fixtures which are described below:

There are other ways they can be fixtured and you are welcome to add configuration scripts to support them and new hardware.

Each target you add can be healhchecked with, for a basic functionality check:

$ tcf healthcheck TARGETNAME
Power is reported correctly as 1
power test passed
TARGETNAME: healthcheck completed

Note this concludes the server installation process; the sections that follow are configuration examples.

3.4.5. Configure physical Linux (or other) targets

There are multiple ways a Linux target can be connected as a target to a TCF server. However, dependending on the intended use, different configuration steps can be followed:

  • A Linux target can be setup to just power on and off.

    This provides no control over the OS installed in the target

  • A Linux target can be setup to boot off a read-only live filesystem (to avoid modifications to the root filesystem) following these steps.

    Serial access to a console can be provided and through it networking can be configured.

  • A PC-class machine can be setup so that via the control of a Provisioning OS, it can be imaged to partition disks or install whichever operating systems in the disks.

    This allows testcases to start by ensuring the machine is properly imaged to a well known setup before starting.

    POS imaging can allow for very fast deployment times (below 1 minute) to fresh OS versions. It requires a more complex setup that depends on the characteristics of the machines to support and it is described here.

3.4.6. Configuring things that get plugged to the targets

A target can declare there are things that are connected to it and that the user might decide to plug or unplug from the command line (see connecting things).

For implementing this, you need:

  • a target
  • a thing (which is also a target)
  • a plugger, which is the driver that implements the actual physical act of plugging one target into another, implementing the interface defined in ttbl.thing_plugger_mixin.

For this, the target to which the thing is connected has to be properly configured; if you are coonecting a THINGNAME using method METHODNAME, in your conf_10_targets.py you would have:

sometarget_add('TARGETNAME' ...)
    'THINGNAME', someplugger(ARG1, ARG2...))

A plugger, such as ttbl.usbrly08b.plugger and its associated physical setup (a USBRLY08b and the cables properly connected) is what allows the physical act of switching. Another example of a plugger would be one that talks to QEMU to route to the VM guest a USB device plugged to the server.

As the things are also target, in a script you need to request both so they are owned by the user and then you can plug them with:

.. code-block:: python
def eval(self, target, thing):
… target.thing_plug(thing) …

As well, in order to make it easy for testcases to locate them and get them assign, it make sense to declare an interconnect that takes both of them, so the target assigner will group them.

For example, if TARGET0 is an MCU that implements a USB device that we connect to TARGET1 and we want to exercise plugging and unplugging it, in the conf_10_target.py file, we would add:

    ic_type = 'usb__host__device')


    'TARGET0', ttbl.usbrly08b.plugger("SERIALNUMBER", 0)) Best practices for server setup Naming targets

Name targets after the type of the target, a monotonically unique number and in some cases, letters that indicate to which networks the target is connected:

  • TYPE: a short name that describes the type of the target

    e.g.: arduino2, minnowboard, arduino101, nuc, genericpc

  • NN is a number that is increased monotonically for each target added to the infrastructure, even of different types:

    • this allows using the number to assign addresses in different spaces (eg: MAC addresses, IPv4 and IPv6, etc)
    • if there are multiple servers in an infrastructure, it is recommended they all share the same number space, so that when a target is moved from one server to another or networks are shared between servers, the addresses don’t conflict
  • x: if the target is connected to a network, append the network name (it is also recommended to name networks nwx, where x is a single character)–if the target is connected to multiple targets, multiple letters can be specified if so chosen.


  • arduino101-03
  • minnowboard-04r
  • nuc-58a Naming Networks

It helps to name networks with a single letter, e.g.: nwa, nwb…*nwr*:

  • it’s a short name and it will fit into network interface names, etc.

  • it allows to use the letter’s ASCII value for naming the IP address ranges and MAC address generation. E.g. a in nwa is 97, 0x61 which can be used to define networks:

    ipv6_addr: fc00::61:0/112
  • as well, as described in the previous section it allows to add a single letter to a target name to indicate which network it is connected to. Configuration Example 1

To add an FRDM k64f board and an Arduino101 board + Flyswatter 2 JTAG, along with a couple of YKush hubs to control them and a DLWPS7 power switch, we’d use the following in /etc/ttbd-production/conf_10_targets.py:


ykush_targets_add("YK20954", "http://admin:1234@sp1/3")
ykush_targets_add("YK20946", "http://admin:1234@sp1/2")

frdm_add(name = "frdm-06",
         serial_number = "0240022636c40e6e000000000000000000000000cb1df3d6",
         ykush_serial = "YK20946",
         ykush_port_board = 3)

arduino101_add(name = "arduino101-02",
               fs2_serial = "FS20000",
               serial_port = "/dev/tty-arduino101-02",
               ykush_url = "http://admin:1234@sp1/2",
               ykush_serial = "YK20954")

This would also require some udev configuration that is explained in the setup instructions for the MCU boards (and detailed here) to generate the right /dev/tty-NAME device links; in short, add to /etc/udev/rules.d/90-ttbd.rules:

SUBSYSTEM == "tty", ENV{ID_SERIAL_SHORT} == "0240022636c40e6e000000000000000000000000cb1df3d6", \
  SYMLINK += "tty-frdm-06"

SUBSYSTEM == "tty", \
  ENV{ID_PATH} == "*2:1.0", \
  PROGRAM = "/usr/bin/usb-sibling-by-serial YK20954", \
  SYMLINK += "tty-arduino101-02"

(reread udev configuration with udevadm control --reload-rules).


Note your serial numbers for the boards and YKush hubs will be different for your setup; see here for boards and here for YKush hubs of how to find them.

Likewise with the definition of the sp1. Add to /etc/hosts:

192.168.x.y   sp1

Where 192.168.x.y is the IP address of the power switch.

As well, setup the proper hardware connections:

  • sp1 connected to the wall and it’s network cable to the server, name sp1 defined in /etc/hosts to the right IP address (see here for details)
  • YK20954’s power connected to the power switch sp1’s socket #3
  • YK20956’s power connected to the power switch sp1’s socket #2
  • frdm-06 USB cable connected to YK20946’s port #3
  • arduino101-2 connected as described here

Restart the server and a listing should show:

$ tcf list

Giving you targets to individually control each power switch’s ports plus the targets themselves.

Once a target is configured in, run a quick healthcheck:

$ tcf healthcheck arduino101-02
Powering off
Powered off
Querying power status
Power is reported correctly as 0
Powering on
Powered on
Querying power status
Power is reported correctly as 1
power test passed
arduino101-02: healthcheck completed

3.4.7. Configuring Provisioning OS support

POS allows for a method to provision/flash/image certain devices using a Provisioning OS which is faster than imaging using standard OS installation procedures. See the architectural refence

POS needs, depending on the setup:

  • targets able to UEFI boot via PXE to the network

    these targets will boot POS over PXE, with the root filesystem in an NFS drive

  • a network interconnect to which the target(s) have to be connected, as well as the server

  • a server acting as an rsync server to provide images to flash into targets; this is usually the same as the TTBD server (for simplicity) the interconnect between the rsync server and the targets needs to be at least 1Gbps to provide the needed performance that will allow to flash a 1G image in less than one minute on a normal harddrive.

    Optional: use glusterfs to coordinate the distribution of images to all the servers FIXME

  • A server providing:

    • the POS linux kernel and initrd over HTTP for targets to boot from PXE
    • the POS image over NFS root for the targets to boot

    this can also be the TTBD server for simplicity and scalability.

Current known POS limitations:

  • Only UEFI PXE boot supported, others device specific
  • Single partitioning scheme supported

Refer to the examples section for usage. POS: Server setup

These instructions are for Fedora only; other distributions have not been tested yet, shall be similar.

  1. Install the auxiliary package ttbd-pos to bring in all the required dependencies:

    # dnf install -y --allowerasing ttbd-pos
  2. Ensure your user is member of the ttbd group:

    # usermod -aG ttbd YOURUSER

    you will have to re-login for changes to take effect.

  3. Configure an image repository (FIXME: add in glusterfs steps); we choose /home/ttbd/images but any other location will do:

    # install -o ttbd -g ttbd -m 2775 -d \
        /home/ttbd \
        /home/ttbd/images/tcf-live/ \
        /home/ttbd/public_html /home/ttbd/public_html/x86_64
  4. Disable the firewall (FIXME: do not require this):

    # systemctl stop firewalld
    # systemctl disable firewalld
  5. Enable required services:

    • Apache: to serve the POS Linux kernel and initrd:

      # tee /etc/httpd/conf.d/ttbd.conf <<EOF
      Alias "/ttbd-pos" "/home/ttbd/public_html"
      <Directory "/home/ttbd/public_html">
      AllowOverride FileInfo AuthConfig Limit Indexes
      Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
      Require method GET POST OPTIONS

      SELinux requires setting a few more things to enable serving from home directories:

      # setsebool -P httpd_enable_homedirs true
      # chcon -R -t httpd_sys_content_t /home/ttbd/public_html

      Test this is working:

      # systemctl restart httpd
      # echo "it works" > /home/ttbd/public_html/testfile

      from any other browser try to access http://YOURSERVERNAME/ttbd-pos/testfile and check it succeeds.

      FIXME: move ttbd.conf file as a config file in package ttbd-pos.

    • NFS server: provides the POS root filesystem.

      Ensure UDP support is enabled:

      # sed -i 's|RPCNFSDARGS="|RPCNFSDARGS="--udp |' /etc/sysconfig/nfs
      # systemctl enable nfs-server
      # systemctl restart nfs-server POS: deploy PXE boot image to HTTP and NFS server locations

Currently the Provisioning OS is implemented with a derivative of Fedora Linux.


these steps are meant for an x86-64 platform and it has to be run in such. Steps for x86 (32-bits) or other platforms need to be documented.

  1. Generate TCF-live on the fly:

    $ /usr/share/tcf/live/mk-liveimg.sh


    • needs sudo access; will ask for your password to gain sudo when needed

    • downloads ~300 packages to create a Fedora-based image, so make sure you have a good connection and plenty of disk space free.

      It will be cached in directory tcf-live so next time you run less needs to be downloaded.

      To use a closer mirror to you or add extra RPM repositories:

      $ mdkir tcf-live
      $ cat > tcf-live/tcf-live-mirror.ks <<EOF
      # Repos needed to pick up TCF internal RPMs
      repo --name=EXTRAREPO --baseurl=https://LOCATION/SOMEWHERE
      # internal mirrors for getting RPMs
      repo --name=fedora-local --cost=-100 --baseurl=http://MIRROR/fedora/linux/releases/$releasever/Everything/$basearch/os/
      repo --name=updates-local --cost=-100 --baseurl=http://MIRROR/fedora/linux/releases/$releasever/Everything/$basearch/os/
  2. Extract the root file system from the ISO image to the /home/ttbd/images directory; this is where the NFS server will read-only root serve it from and also we’ll be able to use it to flash targets:

    $ /usr/share/tcf/tcf-image-setup.sh /home/ttbd/images/tcf-live/x86_64/ tcf-live/tcf-live.iso
    I: loop device /dev/loop0
    loop0       7:0    0  419M  0 loop
    └─loop0p1 259:0    0  419M  0 loop
    mount: /home/LOGIN/tcf-image-setup.sh-XEqBHG/iso: WARNING: device write-protected, mounted read-only.
    I: mounted /dev/loop0p1 in tcf-image-setup.sh-XEqBHG/iso
    I: mounted tcf-image-setup.sh-XEqBHG/iso/LiveOS/squashfs.img in tcf-image-setup.sh-XEqBHG/squashfs
    I: mounted tcf-image-setup.sh-XEqBHG/squashfs/LiveOS/ext3fs.img in tcf-image-setup.sh-XEqBHG/root
    I: created tcf-live, transferring
    I: tcf-live: diffing verification
    File tcf-image-setup.sh-XEqBHG/root/./dev/full is a character special file while file tcf-live/.
    /dev/full is a character special file
    File tcf-image-setup.sh-XEqBHG/root/./dev/zero is a character special file while file tcf-live/.
    /dev/zero is a character special file
    I: unmounting tcf-image-setup.sh-XEqBHG/root
    I: unmounting tcf-image-setup.sh-XEqBHG/squashfs
    I: unmounting tcf-image-setup.sh-XEqBHG/iso
    I: unmounting tcf-image-setup.sh-XEqBHG/root
    umount: tcf-image-setup.sh-XEqBHG/root: not mounted.

    (most of those warning messages during verification can be ignored)

  3. Make the kernel and initrd for POS available via Apache for PXE-over-HTTP and PXE-over-TFTP booting:

    1. Copy the kernel:

      # ln /home/ttbd/images/tcf-live/x86_64/boot/vmlinuz-* \
    2. Regenerate the initrd with nfs-root support, as the initrd generated does not have nfs-root enabled (FIXME: figure out the configuration to enable it straight up):

      # dracut -v -H --kver $(ls /home/ttbd/images/tcf-live/x86_64/lib/modules) \
             -k /home/ttbd/images/tcf-live/x86_64/lib/modules/* \
            --kernel-image /home/ttbd/images/tcf-live/x86_64/boot/vmlinuz-* \
            --add-drivers "igb e1000e r8169 virtio_net ftdi_sio" \
            -m "nfs base network kernel-modules kernel-network-modules" \


      --kver is needed to not default to the kernel version of the system running the co/mmand. -H is needed to ensure a generic initrd that works with multiple machines is created.

      needed drivers:

      • ftdi_sio drivers for FTDI USB serial ports
      • igb, e1000e Intel adapters
      • r8169 for some Realtek network cards
      • virtio for running under QEMU

      Note if you run as non-root (not using sudo or su) dracut will fail to generate the initrd properly due to some bugs.

    3. Make everything readable to the public:

      # chmod a+rX -R /home/ttbd/public_html
      # chcon -R -t httpd_sys_content_t /home/ttbd/public_html
    4. Copy the POS boot material to the TFTP directory:

      # install -m 2775 -o ttbd -g ttbd -d \
      # install -m 0644 -o ttbd -g ttbd /home/ttbd/public_html/x86_64/* \

      This allows targets to get the boot kernel/initrd over TFTP.

    Ensure those two files work by pointing a browser to http://YOURSERVERNAME/ttbd-pos/ and verifying they can be downloaded.

  4. Make the POS root image available over NFS as read-only (note we only export those images only, not all):

    # tee /etc/exports.d/ttbd-pos.exports <<EOF
    /home/ttbd/images/tcf-live/x86_64 *(ro,no_root_squash)
    # systemctl reload nfs-server

    Verify the directory is exported:

    $ showmount -e SERVERNAME
    Export list for localhost:
    /home/ttbd/images/tcf-live/x86_64 * POS: Deploying other images

Image naming follows the format:


it is valid to leave any fields empty except for the DISTRO and ARCH fields; valid examples:

- clear:live:25930::x86_64
- yocto:core-image-minimal:2.5.1::x86_64
- fedora:live:29::x86_64
- fedora:workstation:29::x86_64

The script /usr/share/tcf/tcf-image-setup.sh will take an image from different OSes and extract it so it can be used to be flashed via POS; for example:

  • Clearlinux:

    $ wget https://download.clearlinux.org/releases/25930/clear/clear-25930-live.img.xz
    $ /usr/share/tcf/tcf-image-setup.sh /home/ttbd/images/clear:live:25930::x86_64 clear-25930-live.img.xz
  • Yocto:

    $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-2.5.1/machines/genericx86-64/core-image-minimal-genericx86-64.wic
    $ /usr/share/tcf/tcf-image-setup.sh yocto:core-image-minimal:2.5.1::x86_64 core-image-minimal-genericx86-64.wic
  • (others coming)

Otherewise, an image can be extracted and or setup manually and it consists of:

  • the full root filesystem that shall be deployed

    Note it is important to respect not only the user/group and permisisons of each file, but also any extended attributes (ACLs, SELinux contexts, etc). Look at the insides of tcf-image-setup.sh for a methodology to do it.

  • basic configuration so it starts a serial console on the serial device/s given in the kernel command line

  • (recommended) remove the root password, so it needs no extra steps to login (after all, this is not protecting any infrastructure or access, since the target will be in a silo; as well, the cleartext password would have to be in a test script so it can be entered, so it would make no sense). POS: Configuring networks

For a target to be able to be provisoned via POS, it needs to be connected to an (IPv4) network to the server, which provides DHCP, TFTP and HTTP (for PXE), NFS and rsync support.

TTBD will start the rsync and DHCP servers on demand, TFTP, HTTP and NFS services have been enabled by installing the ttbd-pos package.

To enable the system to know what to use, the network the target is connected to (which is another target) needs to have certain configuration settings.

  1. A network is usually defined, in a conf_10_NAME.py configuration file in /etc/ttbd-production (or any other instance) with a block such as:

        tags = dict(
            ipv6_addr = 'fc00::61:1',
            ipv6_prefix_len = 112,
            ipv4_addr = '',
            ipv4_prefix_len = 24,
        ic_type = "ethernet"

    This defines a target representing an interconnect, called nwa, of type ethernet (vs let’s way WiFi). It is sometimes also called a NUT (Network Under Test). This network defines a single power control implementation, a conf_00_lib.vlan_pci which will upon power on/off create/teardown the internal piping for virtual macines to be able to access said interconnect.

    Note how we have assigned IP addresses to the network, which will be the ones the server connection to it will have. By setting the prefix lengths, we also know the network mask.

    Note also the nomenclature: nwa, letter a )(ASCII 97 / 0x61) which we use in the network part of the IP address (192.168.97.x and fc00::61:x).

  2. Since we know we are using a physical network, in the form of one of the server’s network interfaces connected to a network switch, we ask ttbd to use said network interface by adding a mac_addr tag describing the interface’s MAC address:

    tags = dict(
        mac_addr =  'a0:ce:c8:00:18:73',
        ipv6_addr = 'fc00::61:1',

    Now, powering on or off the nwa target will bring up or down the interface.

  3. If we want to control the power to the network switch, we would add a power control implementation to the target’s power rail after vlan_pci():



    Do not do this if you are using a shared switch split in multiple port groups, as you would power off the switch for other users while they need it.

    This is assuming we have the power to the network switch connected to socket #5 of a Digital Weblogger Switch 7 which the server can reach through the infrastructure network as hostname sp5 (see configuring Digital Loggers Web Power Switch 7) – note other power switches can be used too as long as a driver class is available for them.

  4. Now we need to add DHCP support to the network; we do that by using a DHCP power control interface, that will configure and start a DHCP daemon when the nwa interconnect is powered on, or stop it when is powered off:

                         ttbl.dhcp.pci("", "", 24,
                                       "", ""),
                         ttbl.dhcp.pci("fc00::61:1", "fc00::61:0", 112,
                                       "fc00::61:2", "fc00::61:fe", ip_mode = 6),

    note how we added one for IPv4 and one for IPv6; they both specify the server address as .1, net ‘network” as .0, the prefix len and the range of IP addresses than can be served (note these addresses will be hardcoded–the same IP address will be given always to the same target based on the target’s configuration – more below).

  5. POS can do very fast and efficient imaging by using rsync; the images installed in /home/ttbd/images will be exported by an rsync server daemon controlled by a rsync power control interface, that will configured to start/stop an rsync daemon when the nwa interconnect is powered on/off:

                         ttbl.dhcp.pci("", "", 24,
                                       "", ""),
                         ttbl.dhcp.pci("fc00::61:1", "fc00::61:0", 112,
                                       "fc00::61:2", "fc00::61:fe", ip_mode = 6),
                         ttbl.rsync.pci("", 'images',

    this rsync server binds to IP address, exports a read-only rsync share called images which is anything in /home/ttbd/images

  6. Optionally, you can implement port redirection.

    The NUT nwa is completely isolated from any other networks in your server (unless you have munged with the forwarding rules in the server).

    However, with the socat power control implementation, you can configure one or more port redirections – like a proxy, so that oyur test systems have controlled access to the outside world:

                         ttbl.dhcp.pci("", "", 24,
                                       "", ""),
                         ttbl.dhcp.pci("fc00::61:1", "fc00::61:0", 112,
                                       "fc00::61:2", "fc00::61:fe", ip_mode = 6),
                         ttbl.rsync.pci("", 'images',
                         ttbl.socat.pci('tcp', "", 8080,
                                        'http_proxy.mydomain.com', 8080)
                         ttbl.socat.pci('tcp', "", 1080,
                                        'socks_proxy.mydomain.com', 1080)
  7. Finally, we need to specify a few more tags that the clients and server will use to drive operation:

        tags = dict(
            ipv6_addr = 'fc00::61:1',
            ipv6_prefix_len = 112,
            ipv4_addr = '',
            ipv4_prefix_len = 24,
            ftp_proxy = "",
            http_proxy = "",
            https_proxy =  "",
            # Provisioning OS support to boot off PXE on nfs root
            pos_http_url_prefix = "",
            pos_nfs_server = "",
            pos_nfs_path = "/home/ttbd/images/tcf-live/%(bsp)s",
            pos_rsync_server = "",
        ic_type = "ethernet"

All together, it shall look like:

import ttbl.config
import ttbl.tt
import ttbl.dhcp
import ttbl.rsync
import ttbl.socat

# Delete existing definition of the 'nwa' target created by the
# default initialization
del ttbl.config.targets['nwa']

            # optional, to power control the network switch
            ttbl.dhcp.pci("", "", 24,
                          "", ""),
            ttbl.dhcp.pci("fc00::61:1", "fc00::61:0", 112,
                          "fc00::61:2", "fc00::61:fe", ip_mode = 6),
            ttbl.rsync.pci("", 'images',
            ttbl.socat.pci('tcp', "", 8080,
                           'http_proxy.mydomain.com', 8080),
            ttbl.socat.pci('tcp', "", 1080,
                           'socks_proxy.mydomain.com', 1080),
    tags = dict(
        ipv6_addr = 'fc00::61:1',
        ipv6_prefix_len = 112,
        ipv4_addr = '',
        ipv4_prefix_len = 24,

        ftp_proxy = "",
        http_proxy = "",
        https_proxy =  "",

        # Provisioning OS support to boot off PXE on nfs root
        pos_http_url_prefix = "",
        pos_nfs_server = "",
        pos_nfs_path = "/home/ttbd/images/tcf-live/%(bsp)s",
        pos_rsync_server = "",
    ic_type = "ethernet"

Restart the server and verify nwa works as expected:

# systemctl restart ttbd@production

Diagnose issues reported by systemd in troubleshooting

Now the configuration is loaded and you can run:

$ tcf list -vv nwa
  disabled: False
  fullid: local/nwa
  id: nwa
  ipv4_prefix_len: 24
  ipv6_addr: fc00::61:1
  ipv6_prefix_len: 112
  pos_nfs_path: /home/ttbd/images/tcf-live/%(bsp)s
  powered: False
  things: []
  type: ethernet

Note some values from the tcf list output were omitted for clarity.

Check it can power on and off:

$ tcf acquire nwa
$ tcf power-off nwa
$ tcf power-on nwa
$ tcf power-off nwa POS: Configuring targets

This example connects an Intel NUC5i5425OU called nuc-58 to the network nwa so it can be flashed with POS.


Bill of Materials

  • A PC-class machine (the target):
    • able to UEFI boot over the network
    • serial port available (and it’s cable) or USB port available (and USB-to-USB null modem cable or similar)
    • power cable
    • network cable
    • Monitor, keyboard and mouse for initial configuration, will be disconnected once setup.
  • a free outlet on a PDU unit supported by TCF

Setup the test target fixture

  1. connect the target to a normal power outlet, monitor, keyboard and mouse

  2. start the target, go into the BIOS setup menu

    1. navigate to the boot section:

      • set UEFI to boot off network IPv4 as primary boot source
      • remove any other boot methods (TCF will tell it to boot to local disk via the network boot) [USB, Optical, etc]
      • disable unlimited amount of netwbot boots
    2. navigate to the Power section and enable Power on after AC power loss / power failure.

      This ensures that the target will power on when power is applied via the power controller instead of waiting for the user to press the power button.

    3. From the top level menu or advanced config menus, find the MAC address of the target.

      Alternative, this also can be found by booting any OS in the target (eg: a Linux installation image).

  3. Power off the target, disconnect the power, keep the monitor, keyboard and mouse for now

Connecting the target

  1. connect the target’s power cable to the port selected in the PDU (for this example our PDU is a DLWPS7 named sp6 and we’ll use port #6)

    Label the cable with the target’s name.

  2. connect the serial cable to the target and the other end to the server.

    Find the serial number of the USB serial port connected to the server. We will need it later.

Configuring the system for the target

  1. Pick up a target name.

    For this example, we picked nuc5-58a, the number 58 is then used to decide the IP address that is assigned to this target ( on network a (as defined above).

  2. Configure udev to add a name for the serial device for the target’s serial console USB cable so it can be easily found at /dev/tty-TARGETNAME. Follow these instructions using the cable’s serial number we found in the previous section.

  3. Add a configuration block to the configuration file /etc/ttbd-production/conf_10_targets.py


    we’ll simplify this or template it at some point, it is too long and most things are repetitive

             power_control = [
             serial_ports = [
                 { "port": "/dev/tty-nuc-58a", "baudrate": 115200 }
        tags = {
            'linux': True,
            'bsp_models': { 'x86_64': None },
            'bsps': {
                'x86_64': {
                    'linux': True,
                    'console': 'x86_64',
        target_type = "Intel NUC5i5425OU")
    # plug the target to the interconnect and assign IP addresses
    # that DHCP will always assign
        'nwa', dict(
            mac_addr = "c0:3f:5d:63:51:1d",
            ipv4_addr = '', ipv4_prefix_len = 24,
            ipv6_addr = 'fc00::61:9e', ipv6_prefix_len = 112
    # Configure POS support in the tags
        pos_capable = True,
        pos_boot_interconnect = "nwa",
        pos_boot_dev = "sda",
        pos_partsizes = "1:15:30:10",
        linux_serial_console_default = 'ttyUSB0'
    # activate the POS driver for this target
    # FIXME: this needs to be hidden

Restart the server and verify nuc-58a works as expected:

# systemctl restart ttbd@production
# tcf healthcheck nuc-58a

will try to power on and off the target; observe in the monitor if the target is coming up or not. FIXME: diagose issues

Smoke test

From another machine (or within the server) with TCF installed, flash the POS image itself in the system as an initial smoke test, using /usr/share/tcf/examples/test_pos_deploy.py:

$ IMAGE=tcf:live tcf run -vvvt 'nwa or nuc-58a' /usr/share/tcf/examples/test_pos_deploy.py

FIXME: this will fail now because we don’t have the right regex to catch tcf:live’s root prompt ([0-9]+ $).

List available images:

$ tcf run /usr/share/tcf/examples/test_pos_list_images.py
server10/nwa clear:live:25550::x86_64
server10/nwa clear:live:25890::x86_64
server10/nwa fedora:cloud-base:28::x86_64
server10/nwa yocto:core-minimal:2.5.1::x86_64
PASS0/        toplevel @local: 1 tests (1 passed, 0 error, 0 failed, 0 blocked, 0 skipped, in 0:00:06.635452) - passed

and flash other images by passing the right image name to the IMAGE environment variable:

$ IMAGE=clear:live:25890::x86_64 tcf run -vvvt 'nwa or nuc-58a' /usr/share/tcf/examples/test_pos_deploy.py

(of course, this assumes that image is available in your system; see how to add more).