LINE Notify Gateway

Node Express server for forwarding Prometheus AlertManager alerts

Provides a Node docker image running the included Express server.

This server listens for requests from Prometheus Alert Manager, translates the request to be compliant with the LINE Notify API and forwards the request to the LINE Notify server.

Getting Started

1. Gateway Configuration
2. Ports
3. TLS Configuration
4. Endpoints
5. Alertmanager Configuration
6. Running the Server
7. Adding colors for Severity Levels
8. Tests
9. Contact Information

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Gateway Configuration

Configure the LINE Gateway with the following environmental variables:

ENV Variable Name	Required/Optional	Type	Description
REQUEST_URL	Required	string	URL to forward requests to
PROXY_URL	Optional	string	Proxy server address
DEFAULT_LINE_TOKEN	Optional	string	Default token that will be used if one is not specified in the Alertmanager Configuration
ENABLE_TLS	Optional	boolean	Enables HTTPS Server
NODE_TLS_REJECT_UNAUTHORIZED	Optional	integer	Disable TLS Reject Unauthorized (0 to disable)
NODE_ENV	Optional	String	Set node Environment. Defaults to development, set to production for production environment

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Ports

This server listens for HTTP requests on port 8080.

If TLS is enabled the server listens for HTTPS requests on 8443

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TLS Configuration

The server expects an SSL certificate named crt.pem and an unencrypted private key named key.pem. Place these two files in the ssl folder prior to building the docker image or running the server in a Node environment.

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Endpoints

POST /notify

Post alert requets to this endpoint

Method/Headers

Request methods/headers	value
Method	POST
authorization	Bearer <LINE_token>
content-type	application/json

Body Data Structures

${\textsf{\color{orange}Data}}$

Name	Type	Description
status	string	Status of alert
alerts	array <Alert>	array of Alerts

${\textsf{\color{orange}Alert}}$

Name	Type	Description
labels	Key-Value pairs	Alert labels
annotations	Key-Value pairs	Alert Annotations

For further details see Alertmanager Documentation

GET /

Response

Returns this readme

GET /health

Response

Status Code	Type	Description
200	HealthCheck	Basic Health Check

HealthCheck

Name	Type	Notes
uptime	string	Time server has been running
message	string	Response message
timestamp	string	Time of health check

GET /metrics

Prometheus metrics

---

Alertmanager Configuration

The server expects a request from the Prometheus Alertmanager with LINE token specified in the header:

Sample Request Headers

{gateway-configuration
  'user-agent': 'Alertmanager/0.26.0',
  'content-length': '894',
  authorization: 'Bearer <line_token>',
  'content-type': 'application/json'
}

A properly formatted request can be generated by the following Alertmanager receiver configuration:

Sample Alert Configuration

webhook_configs:
  - url: <gateway_server_url>/notify
    http_config:
      authorization:
        type: Bearer
        credentials_file: <path_to_credential_file>

With such a configuration the LINE token is stored in a credential file:

Sample Credential File

xjHyPpa8FukJU0EDJpRpP8dzT0G8uEPH13yJZbKnCMG

Mounting Credential File

In order not to be exposed, the credential file can be stored as a secret which the docker image can mount.

---

Running the server

You can run this project in several ways:

1. Docker Image

docker build -t <ImageTag> .
docker run <ImageTag>

Configuration

The docker file included in this project set up the server and uses PM2 process manager to manage the process. A basic PM2 configuraiton is provided in ecosystem.config.cjs, please see PM2 Docker Integration Documentation for more information.

If you want to specify environmental variables add them to your docker run command as needed. For example to specify a proxy:

docker run -e PROXY_URL=<proxy_url> <ImageTag>

Or to specify a request url:

docker run -e REQUEST_URL=<request_url> <ImageTag>

2. Direct Install in Node Environment

1. Run npm install to install packages
2. Run npm start to start server

3. Build project and run in Node Environment

1. Run npm install to install packages
2. Run npm run build to compile the typescript app to ./dist
3. In the ./dist folder run node Server.js to start the server

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Adding colors for severity levels

Colors for severity levels are mapped in src/utils/TextUtils.ts

const SEVERITY_LOOKUP = new Map([
  ["none", "🔵"],
  ["warning", "🟡"],
  ["critical", "🔴"],
  ["default", "⚪"],
]);

For other severity levels, add another mapping:

const SEVERITY_LOOKUP = new Map([
  ["none", "🔵"],
  ["warning", "🟡"],
  ["critical", "🔴"],
  ["default", "⚪"],
  ["resolved", "🟢"]
]);

A similar map for Status icons is present in src/utils/TextUtils.ts as well and can be edited in the same fasion as Severity.

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Tests

This project includes a suite of tests located in the src/tests directory. You can run all tests by running

npm run test

You can also run individual tests with the following commands:

Test	Command
MessageUtils	npm run test-message-utils
TextUtils	npm run test-text-utils
NotifyController	npm run test-notify-controller
LineNotifyService	npm run test-line-notify-service

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Contact Information

Please contact the author Alex Holliday if you have any questions or require assistance