Before using your new
Clean it is important to learn about
Device Recovery as it is the second most important aspect to
Topics covered in this section are:
The Methodology Behind Device Recovery¶
pyATS Clean provides a jack-of-all-trades for recovering devices that fail due to device malfunctions or if the clean
process itself fails to execute (see below for details).
Device Recovery can clear the line of a device from the terminal server
and use a powercycler to restart the device. After restarting the device,
Device Recovery will load the golden image
and optionally apply a configuration onto the device.
The major advantage the device recovery feature provides is—you can recover a device and reset it back to a useable state regardless of the current state of the device.
How Device Recovery Works¶
Device Recovery is invoked after every stage and it will determine whether to continue or fail clean.
This may depend on:
The result of the last executed stage.
The connectivity to the device.
If the last stage ran was the
The following diagram explains, in detail, the flow of Device Recovery.
How to Enable Device Recovery¶
Device Recovery requires that you have an
Golden Image for each device which is guaranteed to boot and function
Golden Image can be kept on the device or on a tftp server which is accessible from the device. Once
you have the Golden Image, follow the steps below.
Add the required
Power Cyclerinformation to the
The example below shows where to add the
Terminal Serverand the
See Supported Power Cyclers for a list of available Power Cyclers and their respective arguments that can be used.
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devices: PE1: peripherals: power_cycler: - type: dualcomm connect_type: snmp host: 127.0.0.1 outlets:  terminal_server: # <terminal server device>: <list of lines for the device> # In this case, clearing line 22 would clear the line # connected to 'PE1' my-terminal-server:  my-terminal-server: # Fill out the rest of this device as normal # such as connection info, credentials, etc
device_recoverysection to the
Below you can find the
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Clean YAML - Device Recovery Schema ----------------------------------- devices: <device>: device_recovery: break_count (int): How many attempts to break the booting process once either the console_activity_pattern or the grub_activity_pattern was matched. console_activity_pattern (str, optional): Used only for devices with rommon boot mode. Once the pattern is matched, breaking of the boot process begins. console_breakboot_char (str, optional): Used in conjunction with console_activity_pattern. This is the character(s) to send which should break the rommon booting process. grub_activity_pattern (str, optional): Used only for devices with grub boot mode. Once the pattern is matched, breaking of the boot process begins. grub_breakboot_char (str, optional): Used in conjunction with grub_activity_pattern. This is the character(s) to send which should break the grub booting process. timeout (int): Maximum time in seconds to recover the device. recovery_password (str): Password to login to the device after the boot process completes. powercycler (bool, optional): Should Device Recovery powercycle the device. Defaults to True. powercycler_delay (int, optional): Powercycler delay between on and off in seconds. Defaults to 30. reconnect_delay (int, optional): Once device recovered, delay before final reconnect in seconds. Defaults to 60. clear_line (bool, optional): Should device recovery clear the lines. Defaults to True. post_recovery_configuration (str, optional): Configuration to apply after booting. Defaults to None. golden_image for NXOS --------------------- golden_image (dict, only if 'tftp_boot' from below is not defined): kickstart (str, optional): Golden kickstart image. Defaults to None. system (str, optional): Golden system image. Defaults to None. golden_image for others ----------------------- golden_image (list, only if 'tftp_boot' from below is not defined): Image to boot. tftp_boot (only if 'golden_image' from above is not defined): image (list): Image to boot with. ip_address (list): Management ip address to configure to reach to the TFTP server. subnet_mask (str): Management subnet mask. gateway (str): Management gateway. tftp_server (str): Tftp server is reachable with management interface.
Below you can find a
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Clean YAML - Device Recovery Example ------------------------------------ devices: PE1: device_recovery: grub_activity_pattern: '.*The highlighted entry will be executed automatically in.*' timeout: 600 powercycler_delay: 5 golden_image: - 'GOLDEN IMAGE'
That’s it! Not as bad as it looked! Now
pyATS Clean will handle cases where the device has malfunctioned or is otherwise