Flatcar Container Linux

https://www.flatcar.org/docs
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### Start QEMU Instance

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/qemu

Basic command to start the virtual machine without a graphical interface.

```bash
./flatcar_production_qemu.sh -nographic
```

--------------------------------

### Install and use debugging tools

Source: https://www.flatcar.org/docs/latest/diagnostics/install-debugging-tools

Example of installing and running tcpdump within the toolbox environment.

```bash
[root@srv-3qy0p ~]# dnf -y install tcpdump
[root@srv-3qy0p ~]# tcpdump -i ens3
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on ens3, link-type EN10MB (Ethernet), capture size 65535 bytes
```

--------------------------------

### Clone and Initialize Terraform AWS Setup

Source: https://www.flatcar.org/docs/latest/deploy/cloud/aws-ec2

Commands to clone the example repository and initialize the Terraform environment.

```bash
git clone https://github.com/flatcar/flatcar-terraform.git
# From here on you could directly run it, TLDR:
cd aws
export AWS_ACCESS_KEY_ID=...
export AWS_SECRET_ACCESS_KEY=...
terraform init
# Edit the server configs or just go ahead with the default example
terraform plan
terraform apply
```

--------------------------------

### Install QEMU on Debian or Ubuntu

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/qemu

Use apt-get to install the required QEMU system and utility packages.

```bash
sudo apt-get install qemu-system-x86 qemu-utils
```

--------------------------------

### Start QEMU instance

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Command to launch the newly built QEMU image for validation.

```bash
scripts $ ../build/images/amd64-usr/latest/flatcar_production_qemu.sh
```

--------------------------------

### Start the virtual machine

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/virtualbox

Launch the VM in either standard or headless mode.

```bash
VBoxManage startvm myflatcar
VBoxManage startvm myflatcar --type=headless
```

--------------------------------

### Install QEMU on Arch

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/qemu

Use pacman to install the QEMU package.

```bash
sudo pacman -S qemu
```

--------------------------------

### Install QEMU on Gentoo

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/qemu

Configure USE flags and emerge the QEMU package.

```bash
echo app-emulation/qemu qemu_softmmu_targets_x86_64 virtfs xattr >> /etc/portage/package.use
emerge -av app-emulation/qemu
```

--------------------------------

### Start the development container

Source: https://www.flatcar.org/docs/latest/devguide/kernel-modules

Launch the development container with the necessary capabilities and bind mounts.

```bash
sudo systemd-nspawn \
    --bind=/usr/lib/modules \
    --capability=CAP_NET_ADMIN \
    --image=flatcar_developer_container.bin
```

--------------------------------

### Install QEMU on Fedora or RedHat

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/qemu

Use yum to install the QEMU system and image management packages.

```bash
sudo yum install qemu-system-x86 qemu-img
```

--------------------------------

### Start the SDK container

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Initializes the SDK container with a TTY allocation.

```bash
$ ./run_sdk_container -t
sdk@flatcar-sdk-all-3066_0_0_os-beta-3066_1_0-gcf4ff44a  ~/trunk/src/scripts $ cat sdk_container/.repo/manifests/version.txt
```

--------------------------------

### Example Guestinfo Ignition Configuration

Source: https://www.flatcar.org/docs/latest/deploy/cloud/vmware

Example of setting base64 encoded Ignition data in the VMX configuration.

```text
guestinfo.ignition.config.data = "ewogICJpZ25pdGlvbiI6IHsgInZlcnNpb24iOiAiMi4wLjAiIH0KfQo="
guestinfo.ignition.config.data.encoding = "base64"
```

--------------------------------

### Start the default Toolbox

Source: https://www.flatcar.org/docs/latest/diagnostics/install-debugging-tools

Launch the default Fedora-based toolbox container.

```bash
/usr/bin/toolbox
```

--------------------------------

### Transpiling and Starting the VM

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/immutability-updates-rollbacks

Commands to transpile the Butane configuration and launch the Flatcar QEMU instance.

```bash
cat nginx.yaml | docker run --rm -i quay.io/coreos/butane:latest > nginx.json
./flatcar_production_qemu_uefi.sh -i nginx.json -f 12345:80 -- -nographic -snapshot
```

--------------------------------

### Start Flatcar with the merged configuration

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/advanced-service-config

Launch the VM using the final main.json configuration file.

```bash
./flatcar_production_qemu_uefi.sh -i main.json -f 12345:80 -- -snapshot -nographic
```

--------------------------------

### Server Creation Output

Source: https://www.flatcar.org/docs/latest/deploy/cloud/hetzner

Example output displayed after successfully creating a server on Hetzner Cloud.

```text
Server 48081481 created
IPv4: 37.27.83.94
IPv6: 2a01:4f9:c012:52f1::1
IPv6 Network: 2a01:4f9:c012:52f1::/64
```

--------------------------------

### Packer build output

Source: https://www.flatcar.org/docs/latest/deploy/cloud/hetzner

Example output showing successful creation of x86 and Arm snapshots.

```text
==> Builds finished. The artifacts of successful builds are:
--> hcloud.x86: A snapshot was created: 'flatcar-beta-x86' (ID: 157132241)
--> hcloud.arm: A snapshot was created: 'flatcar-beta-arm' (ID: 157132242)
```

--------------------------------

### Create and start the VM domain

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/libvirt

Uses virt-install to provision the Flatcar VM with the specified Ignition configuration.

```bash
virt-install --connect qemu:///system \
             --import \
             --name flatcar-linux1 \
             --ram 1024 --vcpus 1 \
             --os-variant=unknown \
             --disk size=20,backing_store=/var/lib/libvirt/images/flatcar-linux/flatcar_production_qemu_image.img \
             --graphics=none \
             --qemu-commandline='-fw_cfg name=opt/org.flatcar-linux/config,file=/var/lib/libvirt/flatcar-linux/flatcar-linux1/provision.ign'
```

--------------------------------

### PXE Boot Console Output

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/booting-with-pxe

Example of the console output displayed after a successful PXE boot.

```text
This is localhost.unknown_domain (Linux x86_64 3.10.10+) 19:53:36
SSH host key: 24:2e:f1:3f:5f:9c:63:e5:8c:17:47:32:f4:09:5d:78 (RSA)
SSH host key: ed:84:4d:05:e3:7d:e3:d0:b9:58:90:58:3b:99:3a:4c (DSA)
ens0: 10.0.2.15 fe80::5054:ff:fe12:3456
localhost login:
```

--------------------------------

### View VM Boot Output

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/basics-and-testing

Example of the console output during the Flatcar VM boot process.

```text
[   17.396816] mousedev: PS/2 mouse device common for all mice
[   17.405146] input: Power Button as /devices/LNXSYSTM:00/LNXPWRBN:00/input/input4
[   17.449715] ACPI: button: Power Button [PWRF]
[   17.659038] zram_generator::config[1580]: No configuration found.

[...]

localhost login: core (automatic login)

Flatcar Container Linux by Kinvolk alpha 4372.0.0 for QEMU
core@localhost ~ $
```

--------------------------------

### Define Butane Configuration

Source: https://www.flatcar.org/docs/latest/deploy/cloud/stackit

Example YAML configuration for starting an Nginx container on Flatcar.

```yaml
variant: flatcar
version: 1.0.0
storage:
  directories:
    - path: /var/www
systemd:
  units:
    - name: nginx.service
      enabled: true
      contents: |
        [Unit]
        Description=NGINX example
        After=docker.service coreos-metadata.service
        Requires=docker.service coreos-metadata.service
        [Service]
        EnvironmentFile=/run/metadata/flatcar
        TimeoutStartSec=0
        ExecStartPre=-/usr/bin/docker rm --force nginx1
        ExecStartPre=-/usr/bin/bash -c "echo 'Hello from ${COREOS_OPENSTACK_HOSTNAME}' > /var/www/index.html"
        ExecStart=/usr/bin/docker run --name nginx1 --volume "/var/www:/usr/share/nginx/html:ro" --pull always --log-driver=journald --net host docker.io/nginx:1
        ExecStop=/usr/bin/docker stop nginx1
        Restart=always
        RestartSec=5s
        [Install]
        WantedBy=multi-user.target
```

--------------------------------

### Boot the Instance

Source: https://www.flatcar.org/docs/latest/deploy/cloud/akamai

Boots the configured Linode instance.

```bash
linode-cli linodes boot "${LINODE_ID}"
```

--------------------------------

### Verify Docker Installation

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/basics-and-testing

Test the local Docker setup by running a simple Alpine container.

```bash
docker run --rm -ti alpine sh -c 'echo "Hello, World!"'
```

--------------------------------

### Build and install package

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Attempt to build the package within the SDK chroot to identify missing dependencies.

```bash
~/trunk/src/scripts $ emerge-amd64-usr --newuse <group>/<package>
```

--------------------------------

### Butane Configuration for Nginx

Source: https://www.flatcar.org/docs/latest/deploy/cloud/scaleway

Example YAML configuration to start an Nginx container and display the instance hostname.

```yaml
variant: flatcar
version: 1.0.0
passwd:
  users:
    - name: core
      ssh_authorized_keys:
        - ssh-rsa ABCD...
storage:
  directories:
    - path: /var/www
systemd:
  units:
    - name: nginx.service
      enabled: true
      contents: |
        [Unit]
        Description=NGINX example
        After=docker.service coreos-metadata.service
        Requires=docker.service coreos-metadata.service
        [Service]
        EnvironmentFile=/run/metadata/flatcar
        TimeoutStartSec=0
        ExecStartPre=-/usr/bin/docker rm --force nginx1
        ExecStartPre=-/usr/bin/bash -c "echo 'Hello from ${COREOS_SCALEWAY_HOSTNAME}' > /var/www/index.html"
        ExecStart=/usr/bin/docker run --name nginx1 --volume "/var/www:/usr/share/nginx/html:ro" --pull always --log-driver=journald --net host docker.io/nginx:1
        ExecStop=/usr/bin/docker stop nginx1
        Restart=always
        RestartSec=5s
        [Install]
        WantedBy=multi-user.target
```

--------------------------------

### QEMU Boot Options

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Various commands to launch the VM with specific display, console, and SSH configurations.

```bash
./flatcar_production_qemu.sh -- -display curses
```

```bash
./flatcar_production_qemu.sh -nographic
```

```bash
./flatcar_production_qemu.sh -a ~/.ssh/authorized_keys -p 2223 -- -display curses
```

--------------------------------

### Provision Docker TLS with Butane

Source: https://www.flatcar.org/docs/latest/orchestrate/containers/customizing-docker

Example Butane configuration to automate Docker TLS setup on Flatcar.

```yaml
variant: flatcar
version: 1.0.0
storage:
  files:
    - path: /etc/docker/ca.pem
      mode: 0644
      contents:
        inline: |
          -----BEGIN CERTIFICATE-----
          MIIFNDCCAx6gAwIBAgIBATALBgkqhkiG9w0BAQswLTEMMAoGA1UEBhMDVVNBMRAw
          DgYDVQQKEwdldGNkLWNhMQswCQYDVQQLEwJDQTAeFw0xNTA5MDIxMDExMDhaFw0y
          NTA5MDIxMDExMThaMC0xDDAKBgNVBAYTA1VTQTEQMA4GA1UEChMHZXRjZC1jYTEL
          ... ... ...
    - path: /etc/docker/server.pem
      mode: 0644
      contents:
        inline: |
          -----BEGIN CERTIFICATE-----
          MIIFajCCA1SgAwIBAgIBBTALBgkqhkiG9w0BAQswLTEMMAoGA1UEBhMDVVNBMRAw
          DgYDVQQKEwdldGNkLWNhMQswCQYDVQQLEwJDQTAeFw0xNTA5MDIxMDM3MDFaFw0y
          NTA5MDIxMDM3MDNaMEQxDDAKBgNVBAYTA1VTQTEQMA4GA1UEChMHZXRjZC1jYTEQ
          ... ... ...
    - path: /etc/docker/server-key.pem
      mode: 0644
      contents:
        inline: |
          -----BEGIN RSA PRIVATE KEY-----
          MIIJKAIBAAKCAgEA23Q4yELhNEywScrHl6+MUtbonCu59LIjpxDMAGxAHvWhWpEY
          P5vfas8KgxxNyR+U8VpIjEXvwnhwCx/CSCJc3/VtU9v011Ir0WtTrNDocb90fIr3
          YeRWq744UJpBeDHPV9opf8xFE7F74zWeTVMwtiMPKcQDzZ7XoNyJMxg1wmiMbdCj
          ... ... ...
systemd:
  units:
    - name: docker-tls-tcp.socket
      enabled: true
      contents: |
        [Unit]
        Description=Docker Secured Socket for the API

        [Socket]
        ListenStream=2376
        BindIPv6Only=both
        Service=docker.service

        [Install]
        WantedBy=sockets.target
    - name: docker.service
      dropins:
        - name: flags.conf
          contents: |
            [Service]
            Environment="DOCKER_OPTS=--tlsverify --tlscacert=/etc/docker/ca.pem --tlscert=/etc/docker/server.pem --tlskey=/etc/docker/server-key.pem"
```

--------------------------------

### Example environment file content

Source: https://www.flatcar.org/docs/latest/os-config/host-config/environment-variables

A sample format for an environment file containing newline-separated variable assignments.

```text
COREOS_DIGITALOCEAN_IPV4_ANCHOR_0=X.X.X.X
COREOS_DIGITALOCEAN_IPV4_PRIVATE_0=X.X.X.X
COREOS_DIGITALOCEAN_HOSTNAME=test.example.com
COREOS_DIGITALOCEAN_IPV4_PUBLIC_0=X.X.X.X
COREOS_DIGITALOCEAN_IPV6_PUBLIC_0=X:X:X:X:X:X:X:X
```

--------------------------------

### Launch an interactive bash session

Source: https://www.flatcar.org/docs/latest/orchestrate/containers/getting-started-with-docker

Starts an Ubuntu container with a pseudo-tty and interactive stdin, allowing for manual software installation.

```bash
docker run -t -i ubuntu /bin/bash
```

--------------------------------

### Build and test image

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Create a new image and boot it in QEMU to validate the changes.

```bash
~/trunk/src/scripts $ ./build_image --board=amd64-usr
~/trunk/src/scripts $ ./image_to_vm.sh --from=../build/images/amd64-usr/latest --board=amd64-usr --format qemu
```

--------------------------------

### Butane configuration for Nginx

Source: https://www.flatcar.org/docs/latest/deploy/cloud/brightbox

Example YAML configuration to start an Nginx Docker container and set up systemd units on Flatcar.

```yaml
variant: flatcar
version: 1.0.0
passwd:
  users:
    - name: core
      ssh_authorized_keys:
        - ssh-rsa ABCD...
storage:
  directories:
    - path: /var/www
systemd:
  units:
    - name: nginx.service
      enabled: true
      contents: |
        [Unit]
        Description=NGINX example
        After=docker.service coreos-metadata.service
        Requires=docker.service coreos-metadata.service
        [Service]
        EnvironmentFile=/run/metadata/flatcar
        TimeoutStartSec=0
        ExecStartPre=-/usr/bin/docker rm --force nginx1
        ExecStartPre=-/usr/bin/bash -c "echo 'Hello from ${COREOS_OPENSTACK_HOSTNAME}' > /var/www/index.html"
        ExecStart=/usr/bin/docker run --name nginx1 --volume "/var/www:/usr/share/nginx/html:ro" --pull always --log-driver=journald --net host docker.io/nginx:1
        ExecStop=/usr/bin/docker stop nginx1
        Restart=always
        RestartSec=5s
        [Install]
        WantedBy=multi-user.target
```

--------------------------------

### Start QEmu with 9p storage

Source: https://www.flatcar.org/docs/latest/devguide/kernel-modules

Forward a local host directory to a QEmu instance using 9p to provide sufficient storage for the development container.

```bash
./flatcar_production_qemu_uefi.sh [...other options...] -virtfs local,path="$(pwd)",mount_tag="data",security_model=none,id=data
```

--------------------------------

### Install flatcar-install script

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/raspberry-pi

Downloads and installs the Flatcar installer script to the local user bin directory.

```bash
mkdir -p ~/.local/bin
# You may also add `PATH` export to your shell profile, i.e bashrc, zshrc etc.
export PATH=$PATH:$HOME/.local/bin

curl -LO https://raw.githubusercontent.com/flatcar/init/flatcar-master/bin/flatcar-install
chmod +x flatcar-install
mv flatcar-install ~/.local/bin
```

--------------------------------

### Initialize and Boot Flatcar Image

Source: https://www.flatcar.org/docs/latest/getting-started/quickstart

Create a working copy of the image and start the QEMU virtual machine with an Ignition configuration.

```bash
cp -i --reflink=auto flatcar_production_qemu_image.img.fresh flatcar_production_qemu_image.img
./flatcar_production_qemu.sh -i ignition.json
```

--------------------------------

### Start SSSD service

Source: https://www.flatcar.org/docs/latest/security/cert-auth/sssd

Command to start the SSSD service immediately.

```bash
sudo systemctl start sssd
```

--------------------------------

### Installing Flatcar on VMware

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/installing-to-disk

Command to install the VMware-specific image to a target disk.

```bash
flatcar-install -d /dev/sda -i ignition.json -o vmware_raw
```

--------------------------------

### Prepare fresh QEMU image for provisioning

Source: https://www.flatcar.org/docs/latest/getting-started

Creates a fresh copy of the image to ensure Ignition runs on the first boot.

```bash
mv flatcar_production_qemu_image.img flatcar_production_qemu_image.img.fresh
# If you want to have a first look, boot it and wait for the autologin to give you a prompt:
cp -i --reflink=auto flatcar_production_qemu_image.img.fresh flatcar_production_qemu_image.img
```

--------------------------------

### Install Nebraska with Helm

Source: https://www.flatcar.org/docs/latest/updates-releases/nebraska/authorization

Commands to add the Nebraska Helm repository and perform a default installation.

```bash
$ helm repo add nebraska https://flatcar.github.io/nebraska
$ helm install my-nebraska nebraska/nebraska
```

--------------------------------

### Launch Instance via API

Source: https://www.flatcar.org/docs/latest/deploy/cloud/exoscale

Deploy a virtual machine using the cs command line tool with specific template and service offering IDs.

```bash
cs deployVirtualMachine templateId=2a196b89-0c50-4400-9d42-ef43bcc0fa99 serviceOfferingId=21624abb-764e-4def-81d7-9fc54b5957fb zoneId=1128bd56-b4d9-4ac6-a7b9-c715b187ce11 keyPair=[keypair name]
```

--------------------------------

### Create Instance Configuration Profile

Source: https://www.flatcar.org/docs/latest/deploy/cloud/akamai

Configures the instance to boot from the disk and disables Linode helpers that are incompatible with Flatcar.

```bash
linode-cli linodes config-create \
    --kernel linode/direct-disk \
    --helpers.updatedb_disabled true \
    --helpers.distro false \
    --helpers.modules_dep false \
    --helpers.network false \
    --helpers.devtmpfs_automount false \
    --label default \
    --devices.sda.disk_id "${DISK_ID}" \
    --root_device /dev/sda \
    "${LINODE_ID}"
```

--------------------------------

### Start and Access QEMU VM

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Launch the QEMU VM from the host and connect via SSH to validate modifications.

```bash
scripts $ ../build/images/amd64-usr/latest/flatcar_production_qemu.sh
scripts $ ssh core@localhost -p 2222
core@localhost ~ $ ...
```

--------------------------------

### Download and boot iPXE ISO

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/booting-with-ipxe

Commands to fetch the iPXE ISO and launch it using QEMU.

```bash
wget http://boot.ipxe.org/ipxe.iso
qemu-kvm -m 1024 ipxe.iso -display curses
```

--------------------------------

### Crontab job example

Source: https://www.flatcar.org/docs/latest/os-config/host-config/timers

Example of a standard crontab job scheduled to run every 10 minutes.

```text
*/10 * * * * /usr/bin/date >> /tmp/date
```

--------------------------------

### Launch Flatcar VM with configuration

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/basics-and-testing

Start the QEMU VM with the generated Ignition JSON and port forwarding enabled.

```bash
./flatcar_production_qemu_uefi.sh -i nginx.json -f 12345:80 -- -nographic -snapshot
```

--------------------------------

### Example Commit Message

Source: https://www.flatcar.org/docs/latest/contribute

A practical example of a commit message following the project's formatting standards.

```text
ignition: Update etcd example to use %m

Make the etcd configuration example use ignition's %m instead of the
ETCD_NAME environment variable. Fixes #123.
```

--------------------------------

### View help and configuration options

Source: https://www.flatcar.org/docs/latest/deploy/cloud/gcp

Display all available command-line arguments and environment variables for the upload tool.

```bash
docker run -it ghcr.io/flatcar/google-cloud-flatcar-image-upload --help

Usage: /usr/local/bin/upload_images.sh [OPTION...]

 Required arguments:
  -b, --bucket-name Name of GCP bucket for storing images.
  -p, --project-id  ID of the project for creating bucket. Must be given if CLOUDSDK_CORE_PROJECT is not set.

 Optional arguments:
  -c, --channel     Flatcar Linux release channel. Defaults to 'stable'.
  -v, --version     Flatcar Linux version. Defaults to 'current'.
  -i, --image-name  Image name, which will be used later in Lokomotive configuration. Defaults to 'flatcar-<channel>'.

 Optional flags:
   -f, --force-reupload If used, image will be uploaded even if it already exist in the bucket.
   -F, --force-recreate If user, if compute image already exist, it will be removed and recreated.
   -s, --skip-auth      Skip the authorization steps.
   -u, --image-url      Use direct URL to image

 Environment variables:
   GOOGLE_APPLICATION_CREDENTIALS The credentials file referenced by this will be used for authorization if set.
```

--------------------------------

### Installing Flatcar to a Disk

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/installing-to-disk

Standard command to install Flatcar to a target device using an Ignition configuration file.

```bash
flatcar-install -d /dev/sda -i ignition.json
```

--------------------------------

### Install UEFI firmware to EFI partition

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/raspberry-pi

Mounts the EFI partition and installs the latest RPi4 UEFI firmware.

```bash
# Note `/dev/sda` mentioned in the example needs to be the USB drive that
# we installed flatcar onto
efipartition=$(lsblk /dev/sda -oLABEL,PATH | awk '$1 == "EFI-SYSTEM" {print $2}')
mkdir /tmp/efipartition
sudo mount ${efipartition} /tmp/efipartition
pushd /tmp/efipartition
version=$(curl --silent "https://api.github.com/repos/pftf/RPi4/releases/latest" | jq -r .tag_name)
sudo curl -LO https://github.com/pftf/RPi4/releases/download/${version}/RPi4_UEFI_Firmware_${version}.zip
sudo unzip RPi4_UEFI_Firmware_${version}.zip
sudo rm RPi4_UEFI_Firmware_${version}.zip
popd
sudo umount /tmp/efipartition
```

--------------------------------

### Build and prepare qemu_uefi image

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Commands to build packages and images within the SDK container before running tests.

```bash
./build_packages
./build_image
./image_to_vm.sh --from=../build/images/amd64-usr/latest/ --format=qemu_uefi --image_compression_formats none
```

--------------------------------

### Enable and Start Update Engine

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/immutability-updates-rollbacks

Unmask and start the update-engine service to allow the system to check for and apply updates.

```bash
systemctl unmask update-engine
systemctl enable --now update-engine
```

--------------------------------

### LVM setup systemd unit

Source: https://www.flatcar.org/docs/latest/os-config/storage/lvm

A systemd service unit to execute the LVM setup script during the first boot.

```ini
[Unit]
Description=LVM Setup
ConditionFirstBoot=yes
Before=local-fs-pre.target
[Service]
Type=oneshot
Restart=on-failure
RemainAfterExit=yes
ExecStart=/etc/systemd/multi-user.target/lvm.sh #This is the name and path of the file above
[Install]
WantedBy=multi-user.target
```

--------------------------------

### iPXE boot progress output

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/booting-with-ipxe

Example output showing the iPXE boot script download and kernel image retrieval.

```text
${YOUR_BOOT_URL}... ok
http://alpha.release.flatcar-linux.net/amd64-usr/current/flatcar_production_pxe.vmlinuz... 98%
```

--------------------------------

### Run Flatcar Installation Script

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/installing-to-disk

Execute the installation script pointing to a specific disk, channel, and Ignition configuration file.

```bash
flatcar-install -d /dev/sda -C stable -i ~/ignition.json
```

--------------------------------

### Create and configure VM via CLI

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/proxmoxve

Commands to create a VM, import the disk image, and configure boot settings on the Proxmox host.

```bash
export VM_ID=123

# create the vm and import the image to it's disk
qm create $VM_ID --cores 2 --memory 4096 --net0 "virtio,bridge=vmbr0" --ipconfig0 "ip=dhcp"
qm disk import $VM_ID flatcar_production_proxmoxve_image.img local-lvm

# tell the vm to boot from the imported image
qm set $VM_ID --scsi0 local-lvm:vm-$VM_ID-disk-0
qm set $VM_ID --boot order=scsi0

# Create the cloud-init CD-ROM drive which activates the cloud-init options for the VM.
# This is required for using ignition config as well.
qm set $VM_ID --ide2 local-lvm:cloudinit
```

--------------------------------

### Install Flatcar to disk by channel

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/installing-to-disk

Commands to install the latest version of Flatcar Container Linux for specific release channels.

```bash
flatcar-install -d /dev/sda -C alpha
```

```bash
flatcar-install -d /dev/sda -C beta
```

```bash
flatcar-install -d /dev/sda -C stable
```

--------------------------------

### Start or stop a service

Source: https://www.flatcar.org/docs/latest/os-config/systemd/systemctl

Commands to initiate or terminate a service.

```bash
sudo systemctl start apache.service
```

```bash
sudo systemctl stop apache.service
```

--------------------------------

### Launch and Access Scaleway Instance

Source: https://www.flatcar.org/docs/latest/deploy/cloud/scaleway

Commands to create a server using the snapshot and Ignition file, retrieve its IP, and verify the service status.

```bash
$ INSTANCE_ID=$(scw instance server create image=none root-volume=l:"${SNAPSHOT_ID}" cloud-init=@./ignition.json type=DEV1-S --output=json | jq -r .id)
```

```bash
$ IPV4=$(scw instance server get "${INSTANCE_ID}" --output json | jq -r .public_ip.address)
```

```bash
$ curl "${IPV4}"
Hello from cli-srv-jovial-hamilton
$ ssh core@"${IPV4}"
Flatcar Container Linux by Kinvolk beta 3913.1.0 for Scaleway
core@cli-srv-jovial-hamilton ~ $ systemctl status nginx
● nginx.service - NGINX example
     Loaded: loaded (/etc/systemd/system/nginx.service; enabled; preset: enabled)
     Active: active (running) since Tue 2024-04-23 13:36:35 UTC; 3min 16s ago
    Process: 1560 ExecStartPre=/usr/bin/docker rm --force nginx1 (code=exited, status=0/SUCCESS)
```

--------------------------------

### Booting the Flatcar VM

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Launch the Flatcar VM using the generated QEMU wrapper script from the host terminal.

```bash
$ src/build/images/arm64-usr/developer-latest/flatcar_production_qemu.sh
```

--------------------------------

### Start the iSCSI daemon

Source: https://www.flatcar.org/docs/latest/os-config/storage/iscsi

Initiates the iSCSI service on the system.

```bash
systemctl start iscsid
```

--------------------------------

### Configure Terraform Variables

Source: https://www.flatcar.org/docs/latest/deploy/cloud/digitalocean

Example values for the terraform.tfvars file.

```hcl
cluster_name           = "mycluster"
machines               = ["mynode"]
datacenter             = "nyc3"
ssh_keys               = ["ssh-rsa AA... me@mail.net"]
flatcar_stable_version = "x.y.z"
```

--------------------------------

### Initialize the SDK environment

Source: https://www.flatcar.org/docs/latest/devguide/sdk-modifying-flatcar

Clone the scripts repository and start the SDK container using the latest Alpha release branch.

```bash
$ git clone https://github.com/flatcar/scripts.git
$ cd scripts
$ branch="$(git branch -r -l | awk -F'/' '/origin\/flatcar-[0-9]+$/ {print $2}' | sort | tail -n1)"
$ git checkout "$branch"
$ ./run_sdk_container -t
```

--------------------------------

### Start PostgreSQL container

Source: https://www.flatcar.org/docs/latest/updates-releases/nebraska/development

Run a PostgreSQL container for development purposes.

```bash
docker run --rm -d --name nebraska-postgres-dev -p 5432:5432 -e POSTGRES_PASSWORD=nebraska postgres
```

--------------------------------

### Deploying and Verifying the Flatcar Instance

Source: https://www.flatcar.org/docs/latest/orchestrate/kubernetes/getting-started-with-kubernetes

Commands to compile the Butane configuration and launch the QEMU instance.

```bash
butane < config.yaml > config.json
./flatcar_production_qemu.sh -i config.json -- -display curses
kubectl get nodes
NAME            STATUS     ROLES           AGE     VERSION
flatcar-node1   NotReady   control-plane   2m10s   v1.33.2
```

--------------------------------

### iSCSI configuration file content

Source: https://www.flatcar.org/docs/latest/os-config/storage/iscsi

Example configuration settings for /etc/iscsi/iscsid.conf.

```text
isns.address = host_ip
isns.port = host_port
node.session.auth.username = my_username
node.session.auth.password = my_secret_password
discovery.sendtargets.auth.username = my_username
discovery.sendtargets.auth.password = my_secret_password
```

--------------------------------

### Launch Flatcar with additional storage

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/managing-storage

Starts the Flatcar VM with the additional disk attached via the QEmu wrapper script.

```bash
./flatcar_production_qemu_uefi.sh -snapshot -nographic -drive file=mydisk,driver=qcow2,snapshot=on,media=disk,if=virtio
```

--------------------------------

### Download and install cfssl

Source: https://www.flatcar.org/docs/latest/security/cert-auth/generate-self-signed-certificates

Commands to download the cfssl binaries and add them to the system path.

```bash
mkdir ~/bin
curl -s -L -o ~/bin/cfssl https://pkg.cfssl.org/R1.2/cfssl_linux-amd64
curl -s -L -o ~/bin/cfssljson https://pkg.cfssl.org/R1.2/cfssljson_linux-amd64
chmod +x ~/bin/{cfssl,cfssljson}
export PATH=$PATH:~/bin
```

--------------------------------

### Start Flatcar VM with QEMU

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/basics-and-testing

Launches the Flatcar VM in headless mode with snapshotting enabled to prevent disk modifications.

```bash
./flatcar_production_qemu_uefi.sh -nographic -snapshot
```

--------------------------------

### Enable automatic iSCSI login

Source: https://www.flatcar.org/docs/latest/os-config/storage/iscsi

Configures the iSCSI service to start automatically at boot.

```bash
systemctl enable iscsi
```

--------------------------------

### Manual GRUB Configuration Examples

Source: https://www.flatcar.org/docs/latest/os-config/host-config/other-settings

Directly modify /usr/share/oem/grub.cfg to enable specific features like autologin, debug logging, or masking services.

```bash
set linux_append="$linux_append flatcar.autologin=tty1"
```

```bash
set linux_append="$linux_append systemd.log_level=debug"
```

```bash
set linux_append="$linux_append systemd.mask=systemd-networkd.service"
```

--------------------------------

### Run Flatcar with Ignition config

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/managing-storage

Starts the VM using the generated main.json configuration.

```bash
./flatcar_production_qemu_uefi.sh -i main.json -f 12345:80 -- -snapshot -nographic -drive file=mydisk,driver=qcow2,snapshot=on,media=disk,if=virtio
```

--------------------------------

### QEmu drive configuration option

Source: https://www.flatcar.org/docs/latest/getting-started/learning-series/managing-storage

Command line argument to attach the file-backed storage to the VM using the virtio driver.

```bash
-drive file=mydisk,driver=qcow2,snapshot=on,media=disk,if=virtio
```

--------------------------------

### Manage single machine lifecycle

Source: https://www.flatcar.org/docs/latest/deploy/virt-options/vagrant

Commands to start and access a single Vagrant VM.

```bash
vagrant up
vagrant ssh
```

--------------------------------

### Create a swapfile

Source: https://www.flatcar.org/docs/latest/os-config/storage/adding-swap

Commands to prepare a 1GiB swapfile on Flatcar 4186 and later.

```bash
mkdir -p /var/vm
mkswap --size 1024m --file /var/vm/swapfile1
```

--------------------------------

### Prepare kernel build environment

Source: https://www.flatcar.org/docs/latest/devguide/kernel-modules

Fetch package definitions and prepare the kernel source tree inside the container.

```bash
emerge-gitclone
emerge -gKv coreos-sources
gzip -cd /proc/config.gz > /usr/src/linux/.config
make -C /usr/src/linux modules_prepare
```

--------------------------------

### Configure SSSD for IPA server

Source: https://www.flatcar.org/docs/latest/security/cert-auth/sssd

Example configuration for /etc/sssd/sssd.conf to connect to an IPA server.

```ini
[sssd]
config_file_version = 2
services = nss, pam
domains = LDAP
[nss]
[pam]
[domain/LDAP]
id_provider = ldap
auth_provider = ldap
ldap_schema = ipa
ldap_uri = ldap://ipa.example.com
```

--------------------------------

### Configure PXE boot parameters

Source: https://www.flatcar.org/docs/latest/deploy/bare-metal/booting-with-pxe

Append the custom OEM archive to the initrd line in your pxelinux.cfg file.

```text
...
initrd flatcar_production_pxe_image.cpio.gz,oem.cpio.gz
kernel flatcar_production_pxe.vmlinuz flatcar.first_boot=1
...
```

--------------------------------

### Kubernetes Secret YAML Definition

Source: https://www.flatcar.org/docs/latest/orchestrate/containers/registry-authentication

Example YAML structure for a Kubernetes docker-registry secret.

```yaml
apiVersion: v1
data:
  .dockercfg: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx==
kind: Secret
metadata:
  creationTimestamp: null
  name: my-favorite-registry-secret
type: kubernetes.io/dockercfg
```
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