diff --git a/README.md b/README.md
index d44141c..d4abb08 100644
--- a/README.md
+++ b/README.md
@@ -2,29 +2,43 @@
 
 ## What is this
 
-This module contains reusable terraform modules to reduce boilerplate code. Mainly for M3 company but anyone can use this under [LICENSE](./LICENSE).
+Reusable terraform modules. They are made for M3,Inc.'s internal use. But, anyone able to use them under [LICENSE](./LICENSE).
 
-For example, you can setup ECS cluster + AutoScailing with [ecs_ec2_cluster_template](./ecs_ec2_cluster_template), no need to write many terraform for every applications.
+## Modules
 
-## Documents
+**Setting up services**:
 
-Look `README.md` and `variables.tf` of each module to know it's detail. For example, [ecs_ec2_cluster_template/README.md](./ecs_ec2_cluster_template/README.md) and [ecs_ec2_cluster_template/variables.tf](./ecs_ec2_cluster_template/variables.tf).
+| Module | Description |
+| -------------: | :------------- |
+| [alb_template](./alb_template) | ALB + SSL certificate. |
+| [ecr_repository_template](./ecr_repository_template) | ECR repository with Lifecycle policy. |
+| [ecs_ec2_cluster_template](./ecs_ec2_cluster_template) | ECS nodes with EC2 + AutoScaling. |
+| [ecs_web_service_template](./ecs_web_service_template) | ECS service + ALB target/listener + Route53 record.|
 
-## How to use
+**Monitoring**:
 
-You can load this module from [GitHub registry](https://www.terraform.io/docs/modules/sources.html#github).
+| Module | Description |
+| -------------: | :------------- |
+| [guardduty_slack](./guardduty_slack) | GuardDuty alerts in Slack. |
+| [lambda_monitoring](./lambda_monitoring) | CloudWatch monitoring (alarm) for AWS lambda. |
 
-Only what you need to do is to write following:
+See `README.md` and `variables.tf` of each module for detail.
+
+## Install
+
+We can use modules with `module` blocks:
 
 ```
 module "esc_ec2_cluster_template" {
   source = "github.com/m3dev/m3-terraform-modules//ecs_ec2_cluster_template?ref=495ff58"
 
-  // ... set input variables, see `variables.tf` of the module.
+  // ... set input variables, see `variables.tf` of the mo.
 }
 ```
 
-Note that there are some key points in the `source` URL (see [official document for detail](https://www.terraform.io/docs/modules/sources.html)):
+Note:
+
+- You have to use double slash (`//`) to split repository URL and path from repository root.
+- You should specify tag/branch/revision with `ref`, or your code might be broken when the `master` branch changed.
 
-- Use double slash (`//`) to split repository URL and path from repository root
-- Use `ref` to specify tag/branch/revision to use
+See [the official document](https://www.terraform.io/docs/modules/sources.html)) for detail.
diff --git a/alb_template/README.md b/alb_template/README.md
index 2afa3ab..4e4e87f 100644
--- a/alb_template/README.md
+++ b/alb_template/README.md
@@ -1,6 +1,6 @@
 # AWS ALB template
 
-Create ALB + SSL certificate.
+ALB + SSL certificate.
 
 This module also setup [DNS record](aws_route53_record.tf) and [aws_acm_certificate_validation](aws_acm_certificate_validation.tf) with DNS validation. So that this module requires Route53 hosted zone.
 
diff --git a/ecr_ecs_deploy/README.md b/ecr_ecs_deploy/README.md
new file mode 100644
index 0000000..c80a2de
--- /dev/null
+++ b/ecr_ecs_deploy/README.md
@@ -0,0 +1,19 @@
+# ecr_ecs_deploy
+
+Updates ECS service to force a new deployment when new Docker image is pushed to ECR repository.
+
+It must be useful for a case that ECS task definition refers docker image with ":latest" (or other fixed) tag.
+
+## Inputs
+
+| Name | Description | Type | Default | Required |
+|------|-------------|------|---------|:-----:|
+| docker\_image\_tags | Docker image tag to watch. | `string` | `"latest"` | no |
+| ecr\_repository\_name | Name of ECR repository to watch. | `string` | n/a | yes |
+| ecs\_cluster\_name | Name of ECS cluster which the ECS service belongs to | `string` | n/a | yes |
+| ecs\_service\_name | Arn of ECS service to update | `string` | n/a | yes |
+| name\_prefix | Prefix which is added for some resources. | `string` | `""` | no |
+
+## Outputs
+
+No output.
diff --git a/ecr_ecs_deploy/aws_cloudwatch_event_rule.tf b/ecr_ecs_deploy/aws_cloudwatch_event_rule.tf
new file mode 100644
index 0000000..600db95
--- /dev/null
+++ b/ecr_ecs_deploy/aws_cloudwatch_event_rule.tf
@@ -0,0 +1,28 @@
+resource "aws_cloudwatch_event_rule" "ecr_deploy" {
+  name_prefix = "${var.name_prefix}ecr-put-image"
+  description = "ECR PutImage"
+
+  event_pattern = jsonencode({
+    source = [
+      "aws.ecr"
+    ]
+    "detail" = {
+      eventName = [
+        "PutImage"
+      ]
+      "requestParameters": {
+        "repositoryName": [
+          var.ecr_repository_name
+        ],
+        "imageTag": [
+          var.docker_image_tags
+        ]
+      }
+    }
+  })
+}
+
+resource "aws_cloudwatch_event_target" "slack" {
+  rule = aws_cloudwatch_event_rule.ecr_deploy.name
+  arn = aws_lambda_function.update_ecs_service.arn
+}
diff --git a/ecr_ecs_deploy/aws_iam_role.tf b/ecr_ecs_deploy/aws_iam_role.tf
new file mode 100644
index 0000000..5b6af4f
--- /dev/null
+++ b/ecr_ecs_deploy/aws_iam_role.tf
@@ -0,0 +1,50 @@
+resource "aws_iam_role" "lambda_execution" {
+  name_prefix = "${var.name_prefix}lambda_execution"
+  assume_role_policy = data.aws_iam_policy_document.lambda_execution_assume_role_policy.json
+}
+
+data "aws_iam_policy_document" "lambda_execution_assume_role_policy" {
+  statement {
+    actions = [
+      "sts:AssumeRole"
+    ]
+    principals {
+      type = "Service"
+      identifiers = [
+        "lambda.amazonaws.com"
+      ]
+    }
+  }
+}
+
+
+resource "aws_iam_role_policy_attachment" "lambda_execution" {
+  role = aws_iam_role.lambda_execution.name
+  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
+}
+
+resource "aws_iam_role_policy_attachment" "update_ecs_service" {
+  role = aws_iam_role.lambda_execution.name
+  policy_arn = aws_iam_policy.update_ecs_service.arn
+}
+
+resource "aws_iam_policy" "update_ecs_service" {
+  name = "${var.name_prefix}update_ecs_service"
+  policy = data.aws_iam_policy_document.update_ecs_service.json
+}
+
+resource "random_id" "sid" {
+  byte_length = 8
+}
+
+data "aws_iam_policy_document" "update_ecs_service" {
+  statement {
+    sid = random_id.sid.hex
+    actions = [
+      "ecs:UpdateService"
+    ]
+    resources = [
+      var.ecs_service_arn
+    ]
+  }
+}
diff --git a/ecr_ecs_deploy/aws_lambda_function.tf b/ecr_ecs_deploy/aws_lambda_function.tf
new file mode 100644
index 0000000..a626341
--- /dev/null
+++ b/ecr_ecs_deploy/aws_lambda_function.tf
@@ -0,0 +1,42 @@
+resource "random_id" "suffix" {
+  byte_length = 8
+}
+
+data "aws_ecs_cluster" "cluster" {
+  cluster_name = var.ecs_cluster_name
+}
+
+data "aws_ecs_service" "service" {
+  cluster_arn = data.aws_ecs_cluster.cluster.arn
+  service_name = var.ecs_service_name
+}
+
+resource "aws_lambda_function" "update_ecs_service" {
+  filename = data.archive_file.lambda.output_path
+  function_name = "${var.name_prefix}-update_ecs_service-${random_id.suffix.hex}"
+  role = aws_iam_role.lambda_execution.arn
+  handler = "main.lambda_handler"
+  source_code_hash = data.archive_file.lambda.output_base64sha256
+  runtime = "python3.8"
+  memory_size = 128
+  timeout = 30
+
+  environment {
+    variables = {
+      "EcsServiceArn" = data.aws_ecs_service.service.arn
+      "EcsClusterName" = var.ecs_cluster_name
+    }
+  }
+
+  lifecycle {
+    ignore_changes = [
+      filename,
+    ]
+  }
+}
+
+data "archive_file" "lambda" {
+  type = "zip"
+  source_dir = "${abspath(path.module)}/lambda"
+  output_path = "${abspath(path.module)}/.upload/slack.zip"
+}
diff --git a/ecr_ecs_deploy/aws_lambda_permission.tf b/ecr_ecs_deploy/aws_lambda_permission.tf
new file mode 100644
index 0000000..4de1978
--- /dev/null
+++ b/ecr_ecs_deploy/aws_lambda_permission.tf
@@ -0,0 +1,6 @@
+resource "aws_lambda_permission" "ecr_deploy" {
+  source_arn = aws_cloudwatch_event_rule.ecr_deploy.arn
+  action = "lambda:InvokeFunction"
+  function_name = aws_lambda_function.update_ecs_service.function_name
+  principal = "events.amazonaws.com"
+}
diff --git a/ecr_ecs_deploy/lambda/main.py b/ecr_ecs_deploy/lambda/main.py
new file mode 100644
index 0000000..0a2bc5d
--- /dev/null
+++ b/ecr_ecs_deploy/lambda/main.py
@@ -0,0 +1,32 @@
+import json
+import logging
+import os
+
+import boto3
+
+
+class JsonFormatter:
+    def format(self, record):
+        return json.dumps(record.__dict__)
+
+
+logging.basicConfig()
+logging.getLogger().handlers[0].setFormatter(JsonFormatter())
+logger = logging.getLogger(__name__)
+logger.setLevel(os.environ.get('LOG_LEVEL', 'INFO'))
+
+
+def lambda_handler(event, context):
+    try:
+        service = os.environ['EcsServiceArn']
+        cluster = os.environ['EcsClusterName']
+    except KeyError as e:
+        logger.exception(f'Environment variable not set: {e}')
+        raise
+
+    client = boto3.client("ecs")
+    response = client.update_service(
+        cluster=cluster,
+        service=service,
+        forceNewDeployment=True,
+    )
diff --git a/ecr_ecs_deploy/variables.tf b/ecr_ecs_deploy/variables.tf
new file mode 100644
index 0000000..d1c9b6b
--- /dev/null
+++ b/ecr_ecs_deploy/variables.tf
@@ -0,0 +1,27 @@
+variable "ecr_repository_name" {
+  type = string
+  description = "Name of ECR repository to watch."
+}
+
+variable "ecs_cluster_name" {
+  type = string
+  description = "Name of ECS cluster which the ECS service belongs to"
+}
+
+variable "ecs_service_name" {
+  type = string
+  description = "Arn of ECS service to update"
+}
+
+variable "docker_image_tags" {
+  type = string
+  description = "Docker image tag to watch."
+  default = "latest"
+}
+
+variable "name_prefix" {
+  type = string
+  description = "Prefix which is added for some resources."
+  default = ""
+}
+
diff --git a/ecr_repository_template/README.md b/ecr_repository_template/README.md
index 6ecf0a1..606df6e 100644
--- a/ecr_repository_template/README.md
+++ b/ecr_repository_template/README.md
@@ -1,6 +1,6 @@
 # ecr_repository_template
 
-Create ECR repository with Lifecycle policy.
+ECR repository with Lifecycle policy.
 
 ## Variables
 
diff --git a/ecs_ec2_cluster_template/README.md b/ecs_ec2_cluster_template/README.md
index e571fd2..f8a61de 100644
--- a/ecs_ec2_cluster_template/README.md
+++ b/ecs_ec2_cluster_template/README.md
@@ -1,6 +1,6 @@
 # ecs_ec2_cluster_template
 
-Setup ECS nodes with EC2 + AutoScaling.
+ECS nodes with EC2 + AutoScaling.
 
 Also enable [SSM](https://docs.aws.amazon.com/AmazonECS/latest/developerguide/ec2-run-command.html) so that you can manage instance with it.
 
diff --git a/ecs_web_service_template/README.md b/ecs_web_service_template/README.md
index d3bfd7f..b3248be 100644
--- a/ecs_web_service_template/README.md
+++ b/ecs_web_service_template/README.md
@@ -1,6 +1,6 @@
 # ecs_service_template
 
-Create ECS service + ALB target/listener + Route53 record.
+ECS service + ALB target/listener + Route53 record.
 
 ## Prerequisite
 
diff --git a/guardduty_slack/README.md b/guardduty_slack/README.md
index b638ab7..2ff05eb 100644
--- a/guardduty_slack/README.md
+++ b/guardduty_slack/README.md
@@ -1,5 +1,7 @@
 # guardduty_slack
 
+Notification of GuardDuty for Slack.
+
 This module setups:
 
 - AWS GuardDuty