.. _analyze:

Performance
***********

The :command:`analyze` subcommand helps to analyze ``cloud-init`` boot time
performance. It is loosely based on ``systemd-analyze``, where there are four
subcommands:

- :command:`blame`
- :command:`show`
- :command:`dump`
- :command:`boot`

The analyze subcommand works by parsing the cloud-init log file for timestamps
associated with specific events.

Usage
=====

The :command:`analyze` command requires one of the four subcommands:

.. code-block:: shell-session

   $ cloud-init analyze blame
   $ cloud-init analyze show
   $ cloud-init analyze dump
   $ cloud-init analyze boot

Availability
============

The :command:`analyze boot` subcommand only works on operating systems that
use `systemd`.

Subcommands
===========

:command:`Blame`
----------------

The :command:`blame` subcommand matches :command:`systemd-analyze blame` where
it prints, in descending order, the units that took the longest time to run.
This output is highly useful for examining where ``cloud-init`` is spending
its time.

.. code-block:: shell-session

   $ cloud-init analyze blame

Example output:

.. code-block::

    -- Boot Record 01 --
        00.80300s (init-network/config-growpart)
        00.64300s (init-network/config-resizefs)
        00.62100s (init-network/config-ssh)
        00.57300s (modules-config/config-grub_dpkg)
        00.40300s (init-local/search-NoCloud)
        00.38200s (init-network/config-users_groups)
        00.19800s (modules-config/config-apt_configure)
        00.03700s (modules-final/config-keys_to_console)
        00.02100s (init-network/config-update_etc_hosts)
        00.02100s (init-network/check-cache)
        00.00800s (modules-final/config-ssh_authkey_fingerprints)
        00.00800s (init-network/consume-vendor-data)
        00.00600s (modules-config/config-timezone)
        00.00500s (modules-final/config-final_message)
        00.00400s (init-network/consume-user-data)
        00.00400s (init-network/config-mounts)
        00.00400s (init-network/config-disk_setup)
        00.00400s (init-network/config-bootcmd)
        00.00400s (init-network/activate-datasource)
        00.00300s (init-network/config-update_hostname)
        00.00300s (init-network/config-set_hostname)
        00.00200s (modules-final/config-snappy)
        00.00200s (init-network/config-rsyslog)
        00.00200s (init-network/config-ca_certs)
        00.00200s (init-local/check-cache)
        00.00100s (modules-final/config-scripts_vendor)
        00.00100s (modules-final/config-scripts_per_once)
        00.00100s (modules-final/config-salt_minion)
        00.00100s (modules-final/config-phone_home)
        00.00100s (modules-final/config-package_update_upgrade_install)
        00.00100s (modules-final/config-fan)
        00.00100s (modules-config/config-ubuntu_pro)
        00.00100s (modules-config/config-ssh_import_id)
        00.00100s (modules-config/config-snap)
        00.00100s (modules-config/config-set_passwords)
        00.00100s (modules-config/config-runcmd)
        00.00100s (modules-config/config-locale)
        00.00100s (modules-config/config-byobu)
        00.00100s (modules-config/config-apt_pipelining)
        00.00100s (init-network/config-write_files)
        00.00100s (init-network/config-seed_random)
        00.00000s (modules-final/config-ubuntu_drivers)
        00.00000s (modules-final/config-scripts_user)
        00.00000s (modules-final/config-scripts_per_instance)
        00.00000s (modules-final/config-scripts_per_boot)
        00.00000s (modules-final/config-puppet)
        00.00000s (modules-final/config-power_state_change)
        00.00000s (modules-final/config-mcollective)
        00.00000s (modules-final/config-lxd)
        00.00000s (modules-final/config-landscape)
        00.00000s (modules-final/config-chef)
        00.00000s (modules-config/config-snap_config)
        00.00000s (modules-config/config-ntp)
        00.00000s (modules-config/config-disable_ec2_metadata)
        00.00000s (init-network/setup-datasource)

    1 boot records analyzed

:command:`Show`
---------------

The :command:`show` subcommand is similar to
:command:`systemd-analyze critical-chain` which prints a list of units, the
time they started and how long they took. ``Cloud-init`` has five
:ref:`boot stages<boot_stages>`, and within each stage a number of modules may
run depending on configuration. :command:`cloudinit-analyze show` will, for
each boot, print this information and a summary of the total time.

The following is an abbreviated example of the :command:`show` subcommand:

.. code-block:: shell-session

    $ cloud-init analyze show

Example output:

.. code-block:: shell-session

    -- Boot Record 01 --
    The total time elapsed since completing an event is printed after the "@" character.
    The time the event takes is printed after the "+" character.

    Starting stage: init-local
    |``->no cache found @00.01700s +00.00200s
    |`->found local data from DataSourceNoCloud @00.11000s +00.40300s
    Finished stage: (init-local) 00.94200 seconds

    Starting stage: init-network
    |`->restored from cache with run check: DataSourceNoCloud [seed=/dev/sr0][dsmode=net] @04.79500s +00.02100s
    |`->setting up datasource @04.88900s +00.00000s
    |`->reading and applying user-data @04.90100s +00.00400s
    |`->reading and applying vendor-data @04.90500s +00.00800s
    |`->activating datasource @04.95200s +00.00400s
    Finished stage: (init-network) 02.72100 seconds

    Starting stage: modules-config
    |`->config-snap ran successfully @15.43100s +00.00100s
    ...
    |`->config-runcmd ran successfully @16.22300s +00.00100s
    |`->config-byobu ran successfully @16.23400s +00.00100s
    Finished stage: (modules-config) 00.83500 seconds

    Starting stage: modules-final
    |`->config-snappy ran successfully @16.87400s +00.00200s
    |`->config-package_update_upgrade_install ran successfully @16.87600s +00.00100s
    ...
    |`->config-final_message ran successfully @16.93700s +00.00500s
    |`->config-power_state_change ran successfully @16.94300s +00.00000s
    Finished stage: (modules-final) 00.10300 seconds

    Total Time: 4.60100 seconds

    1 boot records analyzed

If additional boot records are detected then they are printed out from oldest
to newest.

:command:`Dump`
---------------

The :command:`dump` subcommand simply dumps the ``cloud-init`` logs that the
:command:`analyze` module is performing its analysis on, and returns a list of
dictionaries that can be consumed for other reporting needs. Each element in
the list is a boot entry.

.. code-block:: shell-session

    $ cloud-init analyze dump

Example output:

.. code-block::

    [
    {
      "description": "starting search for local datasources",
      "event_type": "start",
      "name": "init-local",
      "origin": "cloudinit",
      "timestamp": 1567057578.037
    },
    {
      "description": "attempting to read from cache [check]",
      "event_type": "start",
      "name": "init-local/check-cache",
      "origin": "cloudinit",
      "timestamp": 1567057578.054
    },
    {
      "description": "no cache found",
      "event_type": "finish",
      "name": "init-local/check-cache",
      "origin": "cloudinit",
      "result": "SUCCESS",
      "timestamp": 1567057578.056
    },
    {
      "description": "searching for local data from DataSourceNoCloud",
      "event_type": "start",
      "name": "init-local/search-NoCloud",
      "origin": "cloudinit",
      "timestamp": 1567057578.147
    },
    {
      "description": "found local data from DataSourceNoCloud",
      "event_type": "finish",
      "name": "init-local/search-NoCloud",
      "origin": "cloudinit",
      "result": "SUCCESS",
      "timestamp": 1567057578.55
    },
    {
      "description": "searching for local datasources",
      "event_type": "finish",
      "name": "init-local",
      "origin": "cloudinit",
      "result": "SUCCESS",
      "timestamp": 1567057578.979
    },
    {
      "description": "searching for network datasources",
      "event_type": "start",
      "name": "init-network",
      "origin": "cloudinit",
      "timestamp": 1567057582.814
    },
    {
      "description": "attempting to read from cache [trust]",
      "event_type": "start",
      "name": "init-network/check-cache",
      "origin": "cloudinit",
      "timestamp": 1567057582.832
    },
    ...
    {
      "description": "config-power_state_change ran successfully",
      "event_type": "finish",
      "name": "modules-final/config-power_state_change",
      "origin": "cloudinit",
      "result": "SUCCESS",
      "timestamp": 1567057594.98
    },
    {
      "description": "running modules for final",
      "event_type": "finish",
      "name": "modules-final",
      "origin": "cloudinit",
      "result": "SUCCESS",
      "timestamp": 1567057594.982
    }
    ]


:command:`Boot`
---------------

The :command:`boot` subcommand prints out kernel-related timestamps that are
not included in any of the ``cloud-init`` logs. There are three different
timestamps that are presented to the user:

- ``kernel start``
- ``kernel finish boot``
- ``cloud-init start``

This was added for additional clarity into the boot process that
``cloud-init`` does not have control over, to aid in debugging performance
issues related to ``cloud-init`` startup, and tracking regression.

.. code-block:: shell-session

    $ cloud-init analyze boot

Example output:

.. code-block::

    -- Most Recent Boot Record --
        Kernel Started at: 2019-08-29 01:35:37.753790
        Kernel ended boot at: 2019-08-29 01:35:38.807407
        Kernel time to boot (seconds): 1.053617000579834
        Cloud-init activated by systemd at: 2019-08-29 01:35:43.992460
        Time between Kernel end boot and Cloud-init activation (seconds): 5.185053110122681
        Cloud-init start: 2019-08-29 08:35:45.867000
    successful

Timestamp gathering
-------------------

The following boot-related timestamps are gathered on demand when
:command:`cloud-init analyze boot` runs:

  - Kernel startup gathered from system uptime
  - Kernel finishes initialization from systemd
    ``UserSpaceMonotonicTimestamp`` property
  - ``Cloud-init`` activation from the property ``InactiveExitTimestamp``
    of the ``cloud-init`` local systemd unit

In order to gather the necessary timestamps using systemd, running the
following command will gather the ``UserspaceTimestamp``:

.. code-block:: shell-session

   $ systemctl show -p UserspaceTimestampMonotonic

Example output:

.. code-block::

   UserspaceTimestampMonotonic=989279

The ``UserspaceTimestamp`` tracks when the init system starts, which is used
as an indicator of the kernel finishing initialisation.

Running the following command will gather the ``InactiveExitTimestamp``:

.. code-block:: shell-session

   $ systemctl show cloud-init-local -p InactiveExitTimestampMonotonic

Example output:

.. code-block::

   InactiveExitTimestampMonotonic=4493126

The ``InactiveExitTimestamp`` tracks when a particular systemd unit
transitions from the `Inactive` to `Active` state, which can be used to mark
the beginning of systemd's activation of ``cloud-init``.

Currently this only works for distros that use systemd as the init process.
We will be expanding support for other distros in the future and this document
will be updated accordingly.

If systemd is not present on the system, ``dmesg`` is used to attempt to find
an event that logs the beginning of the init system. However, with this method
only the first two timestamps are able to be found; ``dmesg`` does not monitor
userspace processes, so no ``cloud-init`` start timestamps are emitted --
unlike when using systemd.
