coal_mine 0.4.18
Coal Mine - Periodic task execution monitor
License: Apache 2.0

Coal Mine - Periodic task execution monitor
===========================================

Home page is `on Github <https://github.com/quantopian/coal-mine/>`__.
Releases are available `in
PyPI <https://pypi.python.org/pypi/coal_mine>`__.

What is Coal Mine?
------------------

Periodic, recurring tasks are ubiquitous in computing, and so one of the
most common problems in systems administration and operations is
ensuring that such tasks execute as expected. Designing the tasks to
report errors is necessary but not sufficient; what if a task isn't
being run at all (crashed daemon, misconfigured crontab) or is running
much more slowly than it should be?

Coal Mine provides a simple yet powerful tool for solving this problem.
In a nutshell:

-  Each recurring task has a Coal Mine "canary" associated with it.
-  The task triggers the canary when it is finished executing.
-  The canary knows how often the task is supposed to execute.
-  Coal Mine alerts by email when a canary is late and alerts again when
   the late canary resumes.
-  Coal Mine keeps a (partial) history of when each canary was
   triggered.

Track tasks that are supposed to execute periodically using "canaries"
that the tasks trigger when they execute. Alert by email when a canary
is late. Alert again when a late canary resumes. Keep a partial history
of canary trigger times.

The server notifies immediately when the deadline for an unpaused canary
passes. Similarly, the server notifies immediately when a previously
late canary is triggered.

Prerequisites
-------------

-  Python 3
-  MongoDB for storage (pull requests to add additional storage engines
   are welcome)
-  requirements listed in requirements.txt
-  for development, requirements listed in requirements\_dev.txt

Concepts
--------

Coal Mine provides two interfaces, a REST API and a command-line
interface (CLI). Since triggering a canary requires nothing more than
hitting its endpoint with a GET or POST query, it's best to do
triggering through the API, so that the CLI doesn't need to be installed
on every system running monitoring tasks. For administrative operations,
on the other hand, the CLI is usually easier.

All timestamps stored and displayed by Coal Mine are in UTC.

Operations
~~~~~~~~~~

The operations that can be performed on canaries through the CLI or API
are:

-  create
-  delete
-  reconfigure
-  get information about
-  pause -- stop monitoring and alerting
-  unpause
-  trigger
-  list -- all canaries or the ones matching search terms

Coal Mine security is rudimentary. If the server is configured with an
optional authentication key, then the key must be specified with all
operations except trigger.

Data
~~~~

These canary attributes are specified when it is created or updated:

-  name
-  description
-  periodicity -- the maximum number of seconds that can elapse before a
   canary is late, *or* a schedule in the format described
   `below <#periodicity>`__, which allows the periodicity of the canary
   to vary over time
-  zero or more notification email address(es)

These are created and maintained by Coal Mine:

-  slug -- the canary's name, lower-cased, with spaces and underscores
   converted to hyphens and other non-alphanumeric characters removed
-  a random identifier consisting of eight lower-case letters, generated
   when the canary is created and guaranteed to be unique against other
   canaries in the database
-  late state (boolean)
-  paused state (boolean)
-  deadline by which the canary should be triggered to avoid being late
-  a history of triggers, pruned when >1000 or (>100 and older than one
   week)

Scheduled periodicity 
^^^^^^^^^^^^^^^^^^^^^^

Coal Mine allows the periodicity of a canary to vary automatically based
on the time, date, day of week, etc. There are three contexts in which
this is useful:

1. a recurring task executes with different frequencies at different
   times;
2. a continuous recurring task takes more or less time to finish at
   different times; or
3. the urgency of responding to delays in a recurring task varies at
   different times.

To specify a varying periodicity for a canary, instead of just
specifying a number of seconds, you specify a serious of `crontab-like
directives <https://github.com/josiahcarlson/parse-crontab>`__ separated
by semicolons. Here's an example, split onto multiple lines for clarity:

::

    # 5-minute delays are ok on weekends ;
    * * * * sat,sun 300 ;
    # 5-minute days are ok overnight ;
    * 0-12 * * mon-fri 300 ;
    # otherwise, we require a shorter periodicity ;
    * 13-23 * * mon-fri 90

Notes:

-  The last field in each directive is the periodicity value, i.e., the
   maximum number of seconds to allow between triggers during the
   specified time range.

-  As indicated above, even though the example is shown split across
   multiple lines, it must be specified all on one line when providing
   it to Coal Mine.

-  Note that comments like the ones shown above really are allowed in
   the schedule you specify to Coal Mine -- they're not just for
   decoration in the example -- but you need to remember to end them
   with semicolons.

-  Schedule directives *cannot overlap*. For example, this won't work,
   because the second directive overlaps with the first one every
   Saturday and Sunday between midnight and noon:

   ::

       * * * * sat,sun 60 ;
       * 0-11 * * * 90

-  If a canary's schedule has gaps, then *the canary is effectively
   paused* during them. For example, in this schedule, the canary would
   be paused all day Saturday:

   ::

       * * * * sun 300 ;
       * * * * mon-fri 60

-  As with everything else in Coal Mine, the hours and minutes specified
   here are in UTC.

-  When you create or update a canary with a periodicity schedule, the
   canary data returned to you in response will include a
   "periodicity\_schedule" field showing how the schedule you specified
   plays out. The schedule will extend far enough into the future for
   each of the directives you specified to be be shown at least once, or
   for a week, whichever is longer.

Installation and configuration
------------------------------

Server
~~~~~~

1. ``pip install coal-mine``
2. Create ``/etc/coal-mine.ini`` (see `below <#ini-file>`__)
3. Run ``coal-mine &``
4. Put that in ``/etc/rc.local`` or something as needed to ensure that
   it is restarted on reboot.

Server configuration file 
^^^^^^^^^^^^^^^^^^^^^^^^^^

The server configuration file, ``coal-mine.ini``, can go in the current
directory where the server is launched, ``/etc``, or ``/usr/local/etc``.
(If you need to put it somewhere else, modify the list of directories
near the top of ``main()`` in ``server.py``.)

The file is (obviously) in INI format. Here are the sections and
settings that it can or must contain:

-  [logging] -- optional
-  file -- log file path; otherwise logging goes to stderr
-  rotate -- if true, then rotate the log file when it gets too large
-  max\_size -- max log file size before rotating (default: 1048576)
-  backup\_count -- number of rotated log files to keep (default: 5)
-  [mongodb] -- required
-  hosts -- the first argument to pymongo 3's MongoClient
-  database -- database name. Coal Mine will create only one collection
   in the database, called "canaries".
-  username -- must be specified, but can be blank if no authentication
   is required
-  password -- must be specified, but can be blank if no authentication
   is required
-  replicaSet -- must be specified if using a replicaset
-  other arguments will be passed through to MongoClient

   -  for example, ssl\_cert\_reqs can can be set to "NONE", "OPTIONAL",
      or "REQUIRED"

-  [email] -- required
-  sender -- email address to put in the From line of notification
   emails
-  [wsgi] -- optional
-  port -- port number the server should listen on (default: 80)
-  auth\_key -- if non-empty, then the specified key must be specified
   as a parameter of the same name with all API requests except
   "trigger".

CLI
~~~

1. ``pip install coal-mine``
2. ``cmcli configure [--host server-host-name] [--port server-port]     [--auth-key key | --no-auth-key]``

The ``--host`` argument can take a URL base (i.e.,
``http://server-host-name`` or ``https://server-host-name``) as well.
This is useful if, for example, you've put your Coal Mine server behind
an SSL proxy so the CLI needs to use SSL to connect to it.

The CLI stores its configuration in ``~/.coal-mine.ini``. Note that the
authentication key is stored in plaintext. Any configuration parameters
the CLI needs that aren't stored in the INI file must be specified
explicitly on the command line when using the CLI.

Using Coal Mine
---------------

CLI
~~~

The Coal Mine CLI, ``cmcli``, provides convenient access to the full
range of Coal Mine's functionality.

To make the CLI easier to use, you can configure it as shown above, but
you also have the option of specifying the server connection information
every time you use it. Also, connnection information specified on the
command line overrides the stored configuration.

Here are some example commands:

::

    cmcli create --help

    cmcli create --name 'My Second Canary' --periodicity $((60*60*25))  # $((60*60*25)) is 25 hours
    cmcli trigger --id aseprogj
    cmcli delete --slug 'my-second-canary'

Run ``cmcli --help`` for more information.

For commands that operate on individual canaries, you can identify the
canary with ``--id``, ``--name``, or ``--slug``. Note that for the
``update`` command, if you want to update the name of a canary you will
need to identify it ``--id`` or ``--slug``, because in that case the
``--name`` argument is used to specify the new name.

API usage examples
------------------

Example commands
~~~~~~~~~~~~~~~~

::

    $ coal-mine &
    [1] 7564
    $ curl 'http://coal-mine-server/coal-mine/v1/canary/create?name=My+First+Canary&periodicity=3600'
    {
        "status": "ok",
        "canary": {
            "deadline": "2015-03-19T02:08:44.885182",
            "id": "fbkvlsby",
            "paused": false,
            "description": "",
            "periodicity": 3600,
            "name": "My First Canary",
            "slug": "my-first-canary",
            "emails": [],
            "history": [
                [
                    "2015-03-19T01:08:44.885182",
                    "Canary created"
                ]
            ],
            "late": false
        }
    }
    $ curl 'http://coal-mine-server/fbkvlsby?comment=short+form+trigger+url'
    {
        "recovered": false,
        "unpaused": false,
        "status": "ok"
    }
    $ curl 'http://coal-mine-server/coal-mine/v1/canary/trigger?slug=my-first-canary&comment=long+form+trigger+url'
    {
        "recovered": false,
        "unpaused": false,
        "status": "ok"
    }
    $ curl 'http://coal-mine-server/coal-mine/v1/canary/get?name=My+First+Canary'
    {
        "canary": {
            "paused": false,
            "name": "My First Canary",
            "history": [
                [
                    "2015-03-19T01:11:56.408000",
                    "Triggered (long form trigger url)"
                ],
                [
                    "2015-03-19T01:10:42.608000",
                    "Triggered (short form trigger url)"
                ],
                [
                    "2015-03-19T01:08:44.885000",
                    "Canary created"
                ]
            ],
            "emails": [],
            "id": "fbkvlsby",
            "late": false,
            "slug": "my-first-canary",
            "deadline": "2015-03-19T02:11:56.408000",
            "periodicity": 3600,
            "description": ""
        },
        "status": "ok"
    }

All API endpoints are fully documented below.

Watching a cron job
~~~~~~~~~~~~~~~~~~~

::

     0 0 * * * my-backup-script.sh && (curl http://coal-mine-server/fbkvlsby &>/dev/null)

API reference
-------------

All API endpoints are submitted as http(s) GET requests. Results are
returned in JSON.

All results have a "status" field which is "ok" on success or "error" on
failure. Failures also return a reasonable HTTP error status code.

Boolean fields in API should be specified as "true", "yes", or "1" for
true, or "false", "no", "0", or empty string for false. Boolean fields
in responses are standard JSON, i.e., "true" or "false".

Timestamps returned by the API are always UTC.

Create canary
~~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/create``

Side effects:

Adds canary to database. Creates history record at current time with
"Canary created" as its comment. Sets deadline to current time plus
periodicity, unless "paused" was specified.

Required parameters:

-  name
-  periodicity
-  auth\_key (if authentication is enabled in the server)

Optional parameters:

-  description - empty if unspecified
-  email - specify multiple times for multiple addresses; no
   notifications if unspecified
-  paused - allows canary to be created already in paused state

Response is the same as shown for get().

Delete canary
~~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/delete``

Required parameters:

-  name, id, or slug
-  auth\_key

Response:

::

    {'status': 'ok'}

Update canary
~~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/update``

Side effects:

Updates the specified canary attributes. Updates deadline to latest
history timestamp plus periodicity if periodicity is updated and canary
is unpaused, and sets late state if new deadline is before now. Sends
notification if canary goes from not late to late or vice versa.

Required parameters:

-  id or slug (*not* name, which should only be specified to update the
   name and slug)
-  auth\_key

Optional parameters:

-  name
-  periodicity
-  description
-  email - specify a single value of "-" to clear existing email
   addresses

Response is the same as shown for get().

Get canary
~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/get``

Required parameters:

-  name, id, or slug
-  auth\_key

Response:

::

    {'status': 'ok',
     'canary': {'name': name,
               'description': description,
               'id': identifier,
               'slug': slug,
               'periodicity': seconds,
               'emails': [address, ...],
               'late': boolean,
               'paused': boolean,
               'deadline': 'YYYY-MM-DDTHH:MM:SSZ',
               'history': [['YYYY-MM-DDTHH:MM:SSZ', comment], ...]}}

List canaries
~~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/list``

Required parameters:

-  auth\_key

Optional parameters:

-  verbose - include all query output for each canary
-  paused - boolean, whether to list paused / unpaused canaries only
-  late - boolean, whether to list late / timely canaries only
-  search - string, regular expression to match against name,
   identifier, and slug

Response:

::

    {'status': 'ok',
     'canaries': [{'name': name,
                 'id': identifier},
                ...]}

If "verbose" is true, then the JSON for each canary includes all the
fields shown above, not just the name and identifier.

Trigger canary
~~~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/trigger``

Also: /*identifier*, in which case the "id" parameter is implied

Note that the server will accept POST requests for triggers as well as
GET requests, so that you can use triggers as webhooks in applications
that expect to be able to POST. The content of the POST is ignored; even
when using POST, the API parameters must still be specified as a query
string.

Side effects:

Sets late state to false. Sets deadline to now plus periodicity. Adds
history record. Prunes history records. Unpauses canary. Generates
notification email if canary was previously late.

Required parameters:

-  name, id, or slug

Optional parameters:

-  comment - stored in history with trigger record

Response:

::

    {'status': 'ok', 'recovered': boolean, 'unpaused': boolean}

-  recovered - indicates whether the canary was previously late before
   this trigger
-  unpaused - indicates whether the canary was previously paused before
   this trigger

Pause canary
~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/pause``

Side effects:

Clears deadline. Sets late state to false if necessary. Pauses canary.
Adds history record about pause. Prunes history records.

Required parameters:

-  name, id, or slug
-  auth\_key

Optional parameters:

-  comment

Response is the same as shown for get().

Unpause canary
~~~~~~~~~~~~~~

Endpoint: ``/coal-mine/v1/canary/unpause``

Side effects:

Sets deadline to now plus periodicity. Unpauses canary. Adds history
record about unpause. Prunes history records.

Required parameters:

-  name, id, or slug
-  auth\_key

Optional parameters:

-  comment

Response is the same as shown for get().

Quis custodiet ipsos custodes?
------------------------------

Obviously, if you're relying on Coal Mine to let you know when something
is wrong, you need to make sure that Coal Mine itself stays running. One
way to do that is to have a cron job which periodically triggers a
canary and generates output (which crond will email to you) if the
trigger fails. Something like:

::

    0 * * * * (curl http://coal-mine-server/atvywzoa | grep -q -s '"status": "ok"') || echo "Failed to trigger canary."

I also recommend using a log-monitoring service such as Papertrail to
monitor and alert about errors in the Coal Mine log.

Contacts
--------

`Github <https://github.com/quantopian/coal-mine>`__

`Email <mailto:opensource@quantopian.com>`__

`PyPI <https://pypi.python.org/pypi/coal_mine>`__

Contributors
------------

Coal Mine was created by Jonathan Kamens, with design help from the
awesome folks at `Quantopian <https://www.quantopian.com/>`__. Thanks,
also, to Quantopian for supporting the development and open-sourcing of
this project.

Development philosophy
----------------------

Use Python.

Do one, simple thing well. There are several similar projects out there
that do more than this project attempts to do.

Make the implementation as simple and straightforward as possible. The
code should be small. What everything does should be obvious from
reading it.

Minimize external dependencies. If something is simple and
straightforward to do ourselves, don't use a third-party package just
for the sake of using a third-party package.

Alternatives
------------

Alternatives to Coal Mine include:

-  `Dead Man's Snitch <https://deadmanssnitch.com/>`__
-  `Cronitor.io <https://cronitor.io/>`__
-  `Sheriff <https://github.com/dawanda/sheriff>`__

We chose to write something new, rather than using what's already out
there, for several reasons:

-  We wanted more control over the stability and reliability of our
   watch service than the commercial alternatives provide.
-  We wanted fine-grained control over the periodicity of our watches,
   as well as assurance that we would be notified immediately when a
   watch is late, something that not all of the alternatives guarantee.
-  We like Python.
-  We like OSS.

To Do
~~~~~

(Pull requests welcome!)

Other storage engines.

Other notification mechanisms.

More smtplib configuration options in INI file.

Web UI.

Links to Web UI in email notifications.

Repeat notifications if a canary remains late for an extended period of
time? Not even sure I want this.

Better authentication?

Support time-zone localization of displayed timestamps.

SSL support in server