package main

import (
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"net/http"
	"net/url"
	"os"
)

const (
	iconEmoji string = ":mega:"
	userName  string = "Hello ECS Job"
	channel   string = "dev"
)

type payload struct {
	Text      string `json:"text"`
	IconEmoji string `json:"icon_emoji"`
	UserName  string `json:"username"`
	Channel   string `json:"channel"`
}

func getWebhookURL() (string, error) {
	webhookURL := os.Getenv("SLACK_WEBHOOK_URL")
	if webhookURL == "" {
		return "", errors.New("The environment value SLACK_WEBHOOK_URL is required.")
	}
	return webhookURL, nil
}

func postToSlack(message, webhookURL string) error {
	p, err := json.Marshal(payload{
		Text:      message,
		IconEmoji: iconEmoji,
		UserName:  userName,
		Channel:   channel,
	})
	if err != nil {
		return err
	}
	resp, err := http.PostForm(webhookURL, url.Values{"payload": {string(p)}})
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	return nil
}

func main() {
	m := flag.String("m", "Hello ECS!!!", "Message posted to Slack")
	flag.Parse()

	webhookUrl, err := getWebhookURL()
	if err != nil {
		fmt.Println("Failed to get Slack Webhook URL.", err.Error())
		return
	}

	if err := postToSlack(*m, webhookUrl); err != nil {
		fmt.Println("Failed to post message to Slack.", err.Error())
	}
}

FROM golang:1.15.5-alpine3.12 as build

ADD . .
RUN go build -o /main

FROM golang:1.15.5-alpine3.12

COPY --from=build /main /main
ENTRYPOINT [ "/main" ]

$ brew install aws/tap/copilot-cli
$ copilot version
version: v1.1.0, built for darwin

$ copilot init
Welcome to the Copilot CLI! We're going to walk you through some questions
to help you get set up with an application on ECS. An application is a collection of
containerized services that operate together.

Application name: hello-ecs
Workload type: Scheduled Job
Job name: hello-ecs-job
Dockerfile: ./Dockerfile
Custom Schedule: */5 * * * *
Your job will run at the following times: Every 5 minutes
Would you like to use this schedule? Yes
Ok great, we'll set up a Scheduled Job named hello-ecs-job in application hello-ecs running on the schedule */5 * * * *.

✔ Created the infrastructure to manage services and jobs under application hello-ecs.

✔ Wrote the manifest for job hello-ecs-job at copilot/hello-ecs-job/manifest.yml
Your manifest contains configurations like your container size and job schedule (*/5 * * * *).

✔ Created ECR repositories for job hello-ecs-job.

All right, you're all set for local development.
Deploy: No

No problem, you can deploy your service later:
- Run `copilot env init --name test --profile default --app hello-ecs` to create your staging environment.
- Update your manifest copilot/hello-ecs-job/manifest.yml to change the defaults.
- Run `copilot job deploy --name hello-ecs-job --env test` to deploy your job to a test environment.

$ .
├── Dockerfile
├── copilot
│   └── hello-ecs-job
│       └── manifest.yml
└── main.go

$ aws ssm put-parameter \
--name /test/slack-webhook \
--value "https://hooks.slack.com/services/XXXXXXXXXXX" \
--type String \
--tags Key=copilot-environment,Value=test Key=copilot-application,Value=hello-ecs

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Condition": {
                "StringEquals": {
                    "ssm:ResourceTag/copilot-environment": "test",
                    "ssm:ResourceTag/copilot-application": "hello-ecs"
                }
            },
            "Action": [
                "ssm:GetParameters"
            ],
            "Resource": [
                "arn:aws:ssm:ap-northeast-1:000000000000:parameter/*"
            ],
            "Effect": "Allow"
        },
        {
            "Condition": {
                "StringEquals": {
                    "secretsmanager:ResourceTag/copilot-application": "hello-ecs",
                    "secretsmanager:ResourceTag/copilot-environment": "test"
                }
            },
            "Action": [
                "secretsmanager:GetSecretValue"
            ],
            "Resource": [
                "arn:aws:secretsmanager:ap-northeast-1:000000000000:secret:*"
            ],
            "Effect": "Allow"
        },
        {
            "Action": [
                "kms:Decrypt"
            ],
            "Resource": [
                "arn:aws:kms:ap-northeast-1:000000000000:key/*"
            ],
            "Effect": "Allow"
        }
    ]
}

- #secrets:                      # Pass secrets from AWS Systems Manager (SSM) Parameter Store.
- #  GITHUB_TOKEN: GITHUB_TOKEN  # The key is the name of the environment variable, the value is the name of the SSM parameter.
+ secrets:                      # Pass secrets from AWS Systems Manager (SSM) Parameter Store.
+  SLACK_WEBHOOK_URL: "/test/slack-webhook"  # The key is the name of the environment variable, the value is the name of the SSM parameter.

$ copilot job deploy --name hello-ecs-job --env test
✘ get environment test configuration: couldn't find environment test in the application hello-ecs

$ copilot env init --name test --profile default --default-config
✔ Proposing infrastructure changes for the hello-ecs-test environment.
- Creating the infrastructure for the hello-ecs-test environment.                    [rollback complete]  [37.1s]0s]
  The following resource(s) failed to create: [InternetGateway, Cluster,                                  
   VPC]. Rollback requested by user.                                                                      
  - An IAM Role for AWS CloudFormation to manage resources                           [not started]         
  - An ECS cluster to group your services.                                           [delete complete]    [2.1s]
    Resource creation cancelled                                                                           
  - An IAM Role to describe resources in your environment                            [not started]         
  - A security group to allow your containers to talk to each other                  [not started]         
  - An Internet Gateway to connect to the public internet                            [delete complete]    [14.4s]
    Resource creation cancelled                                                                           
  - Private subnet 1 for resources with no internet access                           [not started]         
  - Private subnet 2 for resources with no internet access                           [not started]         
  - Public subnet 1 for resources that can access the internet                       [not started]         
  - Public subnet 2 for resources that can access the internet                       [not started]         
  - A Virtual Private Cloud to control networking of your AWS resources              [delete complete]    [2.1s]
    The maximum number of VPCs has been reached. (Service: AmazonEC2; Stat                                
    us Code: 400; Error Code: VpcLimitExceeded; Request ID: 9571d86e-a7e6-                                
    496b-ae4f-5a4797c1c7a0; Proxy: null)                                                                  
✘ stack hello-ecs-test did not complete successfully and exited with status ROLLBACK_COMPLETE

$ copilot env init --name test --profile default --default-config
...
...
✔ Created environment test in region ap-northeast-1 under application hello-ecs.

$ copilot job deploy --name hello-ecs-job --env test
...
...
✔ Deployed hello-ecs-job.