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cachet-url-monitor

Python plugin for cachet that monitors an URL, verifying it's response status and latency. The frequency the URL is tested is configurable, along with the assertion applied to the request response.

This project is available at PyPI: https://pypi.python.org/pypi/cachet-url-monitor

Configuration

endpoints:
  - name: Google
    url: http://www.google.com
    method: GET
    header:
      SOME-HEADER: SOME-VALUE
    timeout: 1 # seconds
    expectation:
      - type: HTTP_STATUS
        status_range: 200-205
      - type: LATENCY
        threshold: 1
      - type: REGEX
        regex: ".*<body>.*"
    allowed_fails: 0
    component_id: 1
    metric_id: 1
    action:
      - UPDATE_STATUS
    public_incidents: true
    latency_unit: ms
    frequency: 5
  - name: Amazon
    url: http://www.amazon.com
    method: GET
    header:
      SOME-HEADER: SOME-VALUE
    timeout: 1 # seconds
    expectation:
      - type: HTTP_STATUS
        status_range: 200-205
        incident: MAJOR
      - type: LATENCY
        threshold: 1
      - type: REGEX
        regex: ".*<body>.*"
        threshold: 10
    allowed_fails: 0
    component_id: 2
    action:
      - CREATE_INCIDENT
    public_incidents: true
    latency_unit: ms
    frequency: 5
  - name: Insecure-site
    url: https://www.Insecure-site-internal.com
    method: GET
    header:
      SOME-HEADER: SOME-VALUE
    insecure: true
    timeout: 1 # seconds
    expectation:
      - type: HTTP_STATUS
        status_range: 200-205
    allowed_fails: 0
    component_id: 2
    action:
      - CREATE_INCIDENT
    public_incidents: true
    frequency: 5
cachet:
  api_url: http://status.cachethq.io/api/v1
  token:
    - type: ENVIRONMENT_VARIABLE
      value: CACHET_TOKEN
    - type: AWS_SECRETS_MANAGER
      secret_name: cachethq
      secret_key: token
      region: us-west-2
    - type: TOKEN
      value: my_token
webhooks:
  - url: "https://push.example.com/message?token=<apptoken>"
    params:
      title: "{title}"
      message: "{message}"
      priority: 5
messages:
  incident_outage: "{name} is unavailable"
  incident_operational: "{name} is operational"
  incident_performance: "{name} has degraded performance"

endpoints, the configuration about the URL/Urls that will be monitored.
- name, The name of the component. This is now mandatory (since 0.6.0) so we can distinguish the logs for each URL being monitored.
- url, the URL that is going to be monitored. mandatory
- method, the HTTP method that will be used by the monitor. mandatory
- header, client header passed to the request. Remove if you do not want to pass a header.
- insecure, for URLs which have self-singed/invalid SSL certs OR you wish to disable SSL check, use this key. Default is false, so by default we validate SSL certs.
- timeout, how long we'll wait to consider the request failed. The unit of it is seconds. mandatory
- expectation, the list of expectations set for the URL. mandatory
  - HTTP_STATUS, we will verify if the response status code falls into the expected range. Please keep in mind the range is inclusive on the first number and exclusive on the second number. If just one value is specified, it will default to only the given value, for example 200 will be converted to 200-201.
  - LATENCY, we measure how long the request took to get a response and fail if it's above the threshold . The unit is in seconds.
  - REGEX, we verify if the response body matches the given regex.
- allowed_fails, create incident/update component status only after specified amount of failed connection trials.
- component_id, the id of the component we're monitoring. This will be used to update the status of the component. mandatory
- metric_id, this will be used to store the latency of the API. If this is not set, it will be ignored.
- action, the action to be done when one of the expectations fails. This is optional and if left blank , nothing will be done to the component.
  - CREATE_INCIDENT, we will create an incident when the expectation fails.
  - UPDATE_STATUS, updates the component status.
  - PUSH_METRICS, uploads response latency metrics.
- public_incidents, boolean to decide if created incidents should be visible to everyone or only to logged in users. Important only if CREATE_INCIDENT or UPDATE_STATUS are set.
- latency_unit, the latency unit used when reporting the metrics. It will automatically convert to the specified unit. It's not mandatory and it will default to seconds. Available units: ms, s, m, h.
- frequency, how often we'll send a request to the given URL. The unit is in seconds.
cachet, this is the settings for our cachet server.
- api_url, the cachet API endpoint. mandatory
- token, the API token. It can either be a string (backwards compatible with old configuration) or a list of token providers. It will read in the specified order and fallback to the next option if no token could be found . (since 0.6.10) mandatory
  - ENVIRONMENT_VARIABLE, it will read the token from the specified environment variable.
  - TOKEN, it's a string and it will be read directly from the configuration.
  - AWS_SECRETS_MANAGER, it will attempt reading the token from AWS Secrets Manager. It requires setting up the AWS credentials into the docker container. More instructions below. It takes these parameters:
    - secret_name, the name of the secret.
    - secret_key, the key under which the token is stored.
    - region, the AWS region.
webhooks, generic webhooks to be notified about incident updates
- url, webhook URL, will be interpolated
- params, POST parameters, will be interpolated
messages, customize text for generated events, use any of endpoint parameter in interpolation
- incident_outage, title of incident in case of outage
- incident_performace, title of incident in case of performance issues
- incident_operational, title of incident in case service is operational

Each expectation has their own default incident status. It can be overridden by setting the incident property to any of the following values:

PARTIAL
MAJOR
PERFORMANCE

By choosing any of the aforementioned statuses, it will let you control the kind of incident it should be considered . These are the default incident status for each expectation type:

Expectation	Incident status
HTTP_STATUS	PARTIAL
LATENCY	PERFORMANCE
REGEX	PARTIAL

Following parameters are available in webhook interpolation

Parameter	Description
`{title}`	Event title, includes endpoint name and short status
`{message}`	Event message, same as sent to Cachet

AWS Secrets Manager

This tools can integrate with AWS Secrets Manager, where the token is fetched directly from the service. In order to get this functionality working, you will need to setup the AWS credentials into the container. The easiest way would be setting the environment variables:

$ docker run --rm -it -e AWS_ACCESS_KEY_ID=xyz -e AWS_SECRET_ACCESS_KEY=aaa -v "$PWD"/my_config.yml:/usr/src/app/config/config.yml:ro mtakaki/cachet-url-monitor

Setting up

The application should be installed using virtualenv, through the following command:

$ git clone https://github.com/mtakaki/cachet-url-monitor.git
$ cd cachet-url-monitor
$ virtualenv venv
$ source venv/bin/activate
$ pip install -r requirements.txt
$ python3 setup.py install

To start the agent:

$ python3 cachet_url_monitor/scheduler.py config.yml

Docker

You can run the agent in docker, so you won't need to worry about installing python, virtualenv, or any other dependency into your OS. The Dockerfile is already checked in and it's ready to be used.

You have two choices, checking this repo out and building the docker image or it can be pulled directly from dockerhub. You will need to create your own custom config .yml file and run (it will pull latest):

$ docker pull mtakaki/cachet-url-monitor
$ docker run --rm -it -v "$PWD":/usr/src/app/config/ mtakaki/cachet-url-monitor

If you're going to use a file with a name other than config.yml, you will need to map the local file, like this:

$ docker run --rm -it -v "$PWD"/my_config.yml:/usr/src/app/config/config.yml:ro mtakaki/cachet-url-monitor

Docker compose

Docker compose has been removed from this repo as it had a dependency on PostgreSQL and it slightly complicated how it works. This has been kindly handled on: https://github.com/boonisz/cachet-url-monitor-dc It facilitates spawning CachetHQ with its dependencies and cachet-url-monitor alongside to it.

Generating configuration from existing CachetHQ instance (since 0.6.2)

In order to expedite the creation of your configuration file, you can use the client to automatically scrape the CachetHQ instance and spit out a YAML file. It can be used like this:

$ python cachet_url_monitor/client.py http://localhost/api/v1 my-token test.yml

Or from docker (you will end up with a test.yml in your $PWD/tmp folder):

$ docker run --rm -it -v $PWD/tmp:/home/tmp/ mtakaki/cachet-url-monitor python3.7 ./cachet_url_monitor/client.py http://localhost/api/v1 my-token /home/tmp/test.yml

The arguments are:

URL, the CachetHQ API URL, so that means appending /api/v1 to your hostname.
token, the token that has access to your CachetHQ instance.
filename, the file where it should write the configuration.

Caveats

Because we can't predict what expectations will be needed, it will default to these behavior:

Verify a [200-300[ HTTP status range.
If status fail, make the incident major and public.
Frequency of 30 seconds.
GET request.
Timeout of 1s.
We'll read the link field from the components and use it as the URL.

Troubleshooting

SSLERROR

If it's throwing the following exception:

raise SSLError(e, request=request)
requests.exceptions.SSLError: HTTPSConnectionPool(host='redacted', port=443): Max retries exceeded with url: /api/v1/components/19 (Caused by SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:579)'),))

It can be resolved by setting the CA bundle environment variable REQUESTS_CA_BUNDLE pointing at your certificate file. It can either be set in your python environment, before running this tool, or in your docker container.

Development

If you want to contribute to this project, feel free to fork this repo and post PRs with any improvements or bug fixes. This is highly appreciated, as it's been hard to deal with numerous requests coming my end.

This repo is setup with pre-commit hooks and it should ensure code style is consistent . The steps to start development on this repo is the same as the setup aforementioned above:

$ git clone https://github.com/mtakaki/cachet-url-monitor.git
$ cd cachet-url-monitor
$ pre-commit install
$ virtualenv venv
$ source venv/bin/activate
$ tox

mtakaki/cachet-url-monitor

mtakaki

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