ASWA (Application Status Watch Agent)

ASWA is a specialized monitoring tool designed to perform HTTP-based health checks on a variety of web endpoints. It is engineered to ping specified URLs and validate their HTTP status codes and content against pre-configured expectations. This enables real-time, automated verification of service availability and data integrity.

Usage

ASWA supports three types of application environments:

• Development (dev): For testing and development purposes.
• Production (prod): For monitoring live, production-level services.
• Software-as-a-Service (saas): For third-party or cloud-based services.

Configuration files are stored in the config directory. You can specify which config file to load (dev, prod, saas) by setting the YAML_PATH environment variable. If no config file is specified, it will default to dev.applications.yml

Run a synthetic test in a docker container:

docker compose run aswa $APP_NAME

docker compose run aswa

Run a synthetic test locally:

./aswa $APP_NAME

./aswa 

Building ASWA binary

To build the ASWA binary, execute the following command:

go build

YAML config

The configuration is defined in a YAML file and must adhere to the following schema:

Required Fields

• name: The name of the application, must be non-empty.
• url: The URL to ping, must be a valid URL and non-empty.
• expected_status: The expected HTTP status code, must be non-zero.

Optional Fields

• expected_content: A string to match against the content returned by the URL.
• expected_location: The expected final URL after all redirects, if any.
• timeout: The maximum time to wait for a response, in milliseconds.
• expected_csp: The expected Content Security Policy (CSP) header value.

applications:
  - name: specialcollections
    url: 'https://specialcollections.library.nyu.edu/search/'
    expected_status: 200
    timeout: 600ms

Environment variables

In the docker-compose.yml file, you can configure the environment variables for the ASWA service. Here is an explanation of the key environment variables:

• ENV: Specifies the environment in which ASWA is running (default is dev).
• DEBUG_MODE: Enables or disables debug mode (default is false).
• CLUSTER_INFO: Includes cluster information in the output.
• OUTPUT_SLACK: If set to true, results are sent to Slack; otherwise, they are sent to PAG (default is false).
• PROM_AGGREGATION_GATEWAY_URL: URL for the Prom Aggregation Gateway.
• SLACK_WEBHOOK_URL: Slack webhook URL for notifications.
• YAML_PATH: Path to the YAML configuration file (default is config/dev.applications.yml).

Notifications

ASWA can post the results of its checks to respective Slack channels (dev, prod, saas) based on the environment. To enable this feature, set the SLACK_WEBHOOK_URL environment variable with your Slack webhook URL.

By default, OUTPUT_SLACK is set to false. If OUTPUT_SLACK is set to true, the results are sent to Slack. If OUTPUT_SLACK is set to false, the results are sent to PAG (Prom Aggregation Gateway). PAG aggregates metrics for Prometheus and is similar in function to Pushgateway but includes metric aggregation capabilities.

Deployment

ASWA is designed to run as a cron job in a Kubernetes (K8s) cluster. To include cluster information in the output, set the CLUSTER_INFO environment variable.

Tests

To run the tests, execute the following command:

Run tests locally:

go test -cover ./...

Run tests in a docker container:

docker compose run test