feat: create a bootc module

cloudinit/config/cc_bootc.py

@@ -0,0 +1,115 @@
+"""Bootc: Switch to a different bootc image."""
+
+import logging
+import os
+
+from cloudinit import subp, util
+from cloudinit.cloud import Cloud
+from cloudinit.config import Config
+from cloudinit.config.schema import MetaSchema
+from cloudinit.distros import ALL_DISTROS
+from cloudinit.settings import PER_INSTANCE
+
+meta: MetaSchema = {
+    "id": "cc_bootc",
+    "distros": [ALL_DISTROS],
+    "frequency": PER_INSTANCE,
+    "activate_by_schema_keys": ["bootc"],
+}
+
+LOG = logging.getLogger(__name__)
+
+def handle(name: str, cfg: Config, cloud: Cloud, args: list) -> None:
+    bootc = cfg.get('bootc')
+    if not bootc:
+        LOG.warning("No 'bootc' configuration found, skipping.")
+        return
+
+    image = util.get_cfg_option_str(bootc, "image")
+    if not image:
+        raise ValueError("No 'image' specified in the 'bootc' configuration.")
+
+    # If Podman is not installed, install it
+    if not os.path.exists("/usr/bin/podman"):
+        install_podman(cloud, image)
+
+    LOG.info(f"Switching to bootc image: {image}")
+
+    try:
+        pull_image(image)
+        install_to_existing_root(image)
+    except Exception as e:
+        LOG.error(f"Failed to switch to bootc image: {e}")
+        raise
+
+    LOG.info("Successfully switched to bootc image")
+    _fire_reboot()
+
+
+def install_podman(cloud: Cloud, image: str) -> None:
+    LOG.info(f"Installing Podman")
+
+    try:
+        cloud.distri.install_packages(["podman"])
+    except Exception as e:
+        LOG.error(f"Failed to install Podman: {e}")
+        raise
+
+
+def pull_image(image: str) -> None:
+    LOG.info(f"Pulling bootc image: {image}")
+
+    try:
+        command = ["podman", "pull", "--tls-verify=false", image]
+        subp.subp(command)
+        LOG.info(f"Successfully executed: {' '.join(command)}")
+    except Exception as e:
+        LOG.error(f"Command failed with error: {e}")
+        raise
+
+
+def install_to_existing_root(image: str) -> None:
+    LOG.info(f"Installing bootc to existing root")
+
+    try:
+        command = [
+            "podman",
+            "run",
+            "--rm",
+            "--privileged",
+            "--volume", "/dev:/dev",
+            "--volume", "/var/lib/containers:/var/lib/containers",
+            "--volume", "/:/target",
+            "--pid=host",
+            "--tls-verify=false",
+            "--security-opt", "label=type:unconfined_t",
+            image,
+            "bootc",
+            "install",
+            "to-existing-root",
+        ]
+        subp.subp(command)
+        LOG.info(f"Successfully executed: {' '.join(command)}")
+    except Exception as e:
+        LOG.error(f"Command failed with error: {e}")
+        raise
+
+
+# Taken from cc_package_update_upgrade_install.py
+def _fire_reboot(
+    wait_attempts: int = 6, initial_sleep: int = 1, backoff: int = 2
+):
+    """Run a reboot command and panic if it doesn't happen fast enough."""
+    subp.subp(REBOOT_CMD)
+    start = time.monotonic()
+    wait_time = initial_sleep
+    for _i in range(wait_attempts):
+        time.sleep(wait_time)
+        wait_time *= backoff
+        elapsed = time.monotonic() - start
+        LOG.debug("Rebooted, but still running after %s seconds", int(elapsed))
+    # If we got here, not good
+    elapsed = time.monotonic() - start
+    raise RuntimeError(
+        "Reboot did not happen after %s seconds!" % (int(elapsed))
+    )

cloudinit/config/schemas/schema-cloud-config-v1.json

@@ -10,6 +10,7 @@
         "apt_configure",
         "apt-pipelining",
         "apt_pipelining",
+        "bootc",
         "bootcmd",
         "byobu",
         "ca-certs",
@@ -1143,6 +1144,15 @@
         }
       }
     },
+    "cc_bootc": {
+      "type": "object",
+      "properties": {
+        "image": {
+          "type": "string",
+          "description": "Target image to use for the next boot"
+        }
+      }
+    },
     "cc_bootcmd": {
       "type": "object",
       "properties": {
@@ -3787,6 +3797,9 @@
     {
       "$ref": "#/$defs/cc_ubuntu_autoinstall"
     },
+    {
+      "$ref": "#/$defs/cc_bootc"
+    },
     {
       "$ref": "#/$defs/cc_bootcmd"
     },
@@ -3949,6 +3962,7 @@
     "apt_upgrade": {},
     "authkey_hash": {},
     "autoinstall": {},
+    "bootc": {},
     "bootcmd": {},
     "byobu_by_default": {},
     "ca-certs": {},
@@ -4039,4 +4053,4 @@
     "zypper": {}
   },
   "additionalProperties": false
-}
+}

config/cloud.cfg.tmpl

@@ -143,6 +143,9 @@ cloud_config_modules:
 {% if variant in ["ubuntu"] %}
   - wireguard
 {% endif %}
+{% if variant in ["fedora"] or is_rhel %}
+  - bootc
+{% endif %}
 {% if variant in ["debian", "ubuntu", "unknown"] %}
   - snap
 {% endif %}

doc/examples/cloud-config-bootc.txt

@@ -0,0 +1,9 @@
+#cloud-config
+
+# bootc
+# default: none
+# This allows you to target a specific bootc image and switch to it
+# If a reboot is required, the system will reboot into the new image
+# and cloud-init will run again
+bootc:
+  image: quay.io/myorg/myimage:latest