Cloud-init

Cloud-init is mixture of Python and Shell scripts that initialize cloud instances of Linux machines. Cloud-init performs boot time configuration of a system. We can configure users, hostname, host network, write files to disk, manage packages, run custom scripts and so on.

##DataSources Datasource is the source of configuration data for cloud-init that is typically given by a user (For example: userdata) or obtained from the cloud that created the configuration drive (For example: metadata). Userdata includes files, YAML configuration files and shell scripts. Metadata includes server name, instance id, display name and other cloud specific details.

Currently there are two datasources used in Photon OS, it’s usage is described in the following sections:

  • DataSourceOVF - Used for GuestOS customization in vSphere.
  • VMwareGuestInfo - Used to read meta, user, and vendor data from VMware vSphere’s GuestInfo interface and initialize the system.

###DataSourceOVF The OVF (Open Virtualization Format) Datasource provides a datasource for reading data from an OVF transport ISO. The vmtoolsd service extracts the customization spec cab file from the OVF and calls either cloud-init or the GuestOS customization scripts. The disable_vmware_customization flag in /etc/cloud/cloud.cfg file determines if GOSC scripts or cloud-init is used.

  • disable_vmware_customization: false : Cloud-init is used for Guest OS customization
  • disable_vmware_customization: true : GuestOS customization scripts is used for Guest OS customization

Note: The default value for disable_vmware_customization is set to true in the /etc/cloud/cloud.cfg file

###VMwareGuestInfo VMwareGuestInfo data source is configured by setting guestinfo properties on a VM. This can be set by performing one of the following:

  • Using the vmware-rpctool provided by open-vmtools.
  • Modifying the vmx file to set the guestinfo properties.

##Debugging Cloud-init Failures Cloud-init has four services which are started in the following sequence:

  1. cloud-init-local - This service locates local data sources and applies networking configurations provided n the metadata (If there is no metadata it applies Fallback). Use $ systemctl status cloud-init-local command to check its status.
  2. cloud-init - This service processes any user-data that is found and runs the cloud_init_modules in /etc/cloud/cloud.cfg. Use $ systemctl status cloud-init command to check its status.
  3. cloud-config - This service runs the cloud_config_modules in /etc/cloud/cloud.cfg file. Use $ systemctl status cloud-config command to check its status.
  4. cloud-final - This service runs any script that a user is accustomed to running after logging into a system (For example: package installations, configs, user-scripts) and runs cloud_final_modules in /etc/cloud/cloud.cfg file. Use $ systemctl status cloud-final command to check its status.

Cloud-init logs are available in the /var/log/cloud-init.log file. Logs for GuestOS customization using DataSourceOVF are available in the /var/log/vmware-imc/toolsDeployPkg.log and /var/log/cloud-init.log files.

To analyze the cloud-init boot time performance, run the following commands:

  • $ cloud-init analyze blame - The blame command prints in descending order, the units that took the longest to run. This output is useful for observe where cloud-init is spending its time during execution.
  • $ cloud-init analyze show - The show command prints a list of units, the time they started and how long they took to complete. It also prints a summary of total time per boot.
  • $ cloud-init analyze dump - The dump command dumps the cloud-init logs for the analyze modules and displays a list of dictionaries that can be consumed for other reporting needs.
  • $ cloud-init status - To know the overall status of clouf-init.

Cloud-init doesn’t configure the network if /etc/cloud/cloud.cfg.d/99-disable-networking-config.cfg file is present and has the following content:

  • network:Item
  • config: disabled

Take a backup of /etc/cloud/cloud.cfg.d/99-disable-networking-config.cfg file and remove it from it’s location. Reconfigure the machine using metadata, userdata and vendordata. Once the configurations are done copy the backup file to the same location. Cloud-init will push it’s fallback configuration when service is restarted or rebooted and there is no local datasource to configure. To avoid this /etc/cloud/cloud.cfg.d/99-disable-networking-config.cfg file is required.

##Run Cloud-init Manually To run cloud-init manually, run the following commands:

/usr/bin/cloud-init -d init  (-d for debug)
/usr/bin/cloud-init -d modules (run all modules)
/usr/bin/cloud-init --file <config-yaml-file-path> init (if you want to run cloud-init with a configuration yaml file)

When cloud-init is running, to force it to run with all configs engaged run the following command:

rm -rf /var/lib/cloud/*

For more information about cloud-init, see https://cloudinit.readthedocs.io/en/latest/index.htmlhttps://cloudinit.readthedocs.io/en/latest/index.html

For more information about cloud-init CLI, see https://cloudinit.readthedocs.io/en/latest/topics/cli.htmlhttps://cloudinit.readthedocs.io/en/latest/topics/cli.html

Note:Include the cloud-init log tarball and the vmtoolsd logs when you raise an issue.

  1. Collect cloud-init log tarball by running the cloud-init collect-logs command.
  2. Collect the vmtoolsd logs from /var/log/vmware-imc/toolsDeployPkg.log file.
  3. Attach the collected logs to the issue ticket.
Last modified March 5, 2021: setting up github actions (3f54ed117)