Added slack endpoint for alerting

.gitignore

@@ -35,4 +35,5 @@ terraform.rc
 
 *.zip
 test/
-**/node_modules/*
\ No newline at end of file
+**/node_modules/*
+.vscode/

.gitlab-ci.yml

@@ -111,4 +111,4 @@ Production Destroy:
     - terraform destroy -auto-approve
   rules: 
     - if: '$CI_COMMIT_BRANCH == "production"'
-      when: manual
\ No newline at end of file
+      when: manual

deploy/cloudwatch_alarms.tf

 data "aws_sns_topic" "cloudmon" {
-  name = "edebrye-cloudmon"
+  name = var.sns_topic_name
 }
 
 resource "aws_cloudwatch_metric_alarm" "lambda_throttles_alarm" {
@@ -41,4 +41,46 @@ resource "aws_cloudwatch_metric_alarm" "lambda_error_alarm" {
     FunctionName = aws_lambda_function.crud[each.key].function_name
   }
   tags = local.common_tags
+}
+
+resource "aws_lambda_function" "slack" {
+  filename                       = data.archive_file.lambda_slack_file.output_path
+  function_name                  = "${local.prefix}-slack-messaging"
+  role                           = aws_iam_role.iam_for_lambda.arn
+  handler                        = "slack.lambda_handler"
+  timeout                        = 10
+  source_code_hash               = data.archive_file.lambda_slack_file.output_base64sha256
+  runtime                        = "python3.8"
+  reserved_concurrent_executions = 2
+  layers = [
+    "arn:aws:lambda:eu-west-1:580247275435:layer:LambdaInsightsExtension:14"
+  ]
+
+  environment {
+    variables = {
+      SLACK_WEBHOOK_URL = var.slack_webhook_url
+    }
+  }
+
+  tags = local.common_tags
+}
+
+data "archive_file" "lambda_slack_file" {
+  type        = "zip"
+  output_path = "${local.lambda_loc}/zip/slack.zip"
+  source_file = "${local.lambda_loc}/slack/slack.py"
+}
+
+resource "aws_sns_topic_subscription" "topic_lambda" {
+  topic_arn = data.aws_sns_topic.cloudmon.arn
+  protocol  = "lambda"
+  endpoint  = aws_lambda_function.slack.arn
+}
+
+resource "aws_lambda_permission" "with_sns" {
+  statement_id  = "AllowExecutionFromSNS"
+  action        = "lambda:InvokeFunction"
+  function_name = aws_lambda_function.slack.arn
+  principal     = "sns.amazonaws.com"
+  source_arn    = data.aws_sns_topic.cloudmon.arn
 }
\ No newline at end of file

deploy/lambda/slack/slack.py

+#!/usr/bin/python3.8
+import urllib3
+import json
+import os
+http = urllib3.PoolManager()
+def lambda_handler(event, context):
+    url = os.getenv("SLACK_WEBHOOK_URL")
+    print(json.dumps(event))
+    messages = [json.loads(i.get('Sns',{}).get('Message',"")) for i in event.get('Records',[])]
+    text=[]
+    for m in messages:
+        text.append("ALARM - Details :\n"+ \
+"\t- Name : "+m.get('AlarmName')+"\n"+ \
+"\t- Description : "+m.get('AlarmDescription')+"\n"+ \
+"\t- New State Value : "+m.get('NewStateValue')+"\n"+ \
+"\t- New State Reason : "+m.get('NewStateReason')+"\n"+ \
+"\t- New State Time : "+m.get('StateChangeTime')+"\n")
+    msg = {
+        "text": "\n-------\n".join(text)
+    }
+    
+    encoded_msg = json.dumps(msg).encode('utf-8')
+    resp = http.request('POST',url, body=encoded_msg)
+    print(json.dumps({
+        "messages": messages,
+        "status_code": resp.status,
+        "response": resp.data.decode("utf-8")
+        })
+    )
\ No newline at end of file

deploy/variables.tf

@@ -18,4 +18,12 @@ variable "aws_region" {
   default = "eu-west-1"
 }
 
+variable "slack_webhook_url" {
+  sensitive = true
+  type      = string
+}
 
+variable "sns_topic_name" {
+  default = "edebrye-cloudmon"
+  type    = string
+}