Using aws ecs with s3storageread

Question

Pulumi · Accepted Answer

To implement a scenario where you use AWS Elastic Container Service (ECS) with an S3 bucket readable from the ECS tasks, we'll write a Pulumi program to accomplish the following:

1. Create an ECS cluster to organize and manage the ECS services and tasks.
2. Define a task definition that describes how the tasks should run, including the container images and resource requirements.
3. Specify the necessary IAM roles to allow our ECS tasks to read from an S3 bucket.
4. Create an S3 bucket that our ECS tasks will access.
5. Create an ECS service to run and maintain the desired number of tasks based on the task definition.
6. Lastly, output the relevant information, such as the S3 bucket name, that the ECS tasks will interact with.

We'll use the `awsx` and `aws` packages from Pulumi, which will provide us with the higher-level abstractions (through `awsx`) and the ability to fine-tune resource properties (when needed) via the `aws` package.

Here's a Pulumi program in TypeScript that sets this up:

```typescript
import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";
import * as awsx from "@pulumi/awsx";

// Create an ECS cluster
const cluster = new awsx.ecs.Cluster("my-cluster", {});

// Create an IAM Policy that allows read-only access to a specific S3 bucket
const readOnlyS3Policy = new aws.iam.Policy("readOnlyS3Policy", {
    description: "A policy that allows read-only access to a specific S3 bucket",
    policy: pulumi.interpolate`{
        "Version": "2012-10-17",
        "Statement": [{
            "Effect": "Allow",
            "Action": ["s3:Get*", "s3:List*"],
            "Resource": ["arn:aws:s3:::my-bucket", "arn:aws:s3:::my-bucket/*"]
        }]
    }`,
});

// Create an IAM Role and attach the read-only policy
const taskExecutionRole = new aws.iam.Role("task-execution-role", {
    assumeRolePolicy: `{
        "Version": "2012-10-17",
        "Statement": [{
            "Action": "sts:AssumeRole",
            "Effect": "Allow",
            "Principal": {"Service": "ecs-tasks.amazonaws.com"}
        }]
    }`,
});

// Attach the read-only policy to the execution role
new aws.iam.RolePolicyAttachment("read-only-s3-policy-attachment", {
    role: taskExecutionRole.name,
    policyArn: readOnlyS3Policy.arn,
});

// Define an ECS task definition that uses the execution role and has read access to S3
const taskDefinition = new awsx.ecs.FargateTaskDefinition("my-task-def", {
    executionRole: taskExecutionRole,
    containers: {
        my_container: {
            image: "my-docker-image", // Replace with your docker image
            memory: 512,
            portMappings: [new awsx.ecs.PortMapping()],
        },
    },
});

// Create an S3 bucket
const bucket = new aws.s3.Bucket("my-bucket", {
    acl: "private",
});

// Create an ECS Service based on the task definition, and run within the cluster
const service = new awsx.ecs.FargateService("my-service", {
    cluster,
    taskDefinition: taskDefinition,
    desiredCount: 2, // Specify the number of tasks to run
});

// Export the S3 bucket name
export const bucketName = bucket.id;

// Export the ECS cluster name
export const ecsClusterName = cluster.id;
```

### Explanation

- **ECS Cluster**: We start by creating an ECS cluster, which allows us to organize our services and tasks.

- **IAM Role and Policy**: We define an IAM role that grants the ECS tasks the necessary permissions to read from an S3 bucket. We also create a policy specifying what actions are allowed (read operations) on which resources (our S3 bucket).

- **ECS Task Definition**: This is where we describe the configuration of our ECS tasks, including the container image, memory allocation, and IAM role for execution.

- **S3 Bucket**: We create an S3 bucket with private access, which will store the data our ECS tasks will read.

- **ECS Service**: This service manages the tasks based on the task definition, ensuring that the desired number of tasks are always running.

- **Exposing Outputs**: The `export` statements make key resource identifiers available outside of Pulumi for other systems and tools to use.

The Pulumi program we've written assumes that you have Docker images available for deploying into the ECS task. Replace `"my-docker-image"` with the appropriate image for your use case.

To use this code, ensure you have Pulumi and AWS CLI set up, and then deploy it using Pulumi's CLI tools.

Please note that in the IAM policy, `"arn:aws:s3:::my-bucket"` should be replaced with the actual ARN of your S3 bucket after its creation if you need fine-grained permissions. For simplicity, we're creating a new S3 bucket and using its name directly within the IAM policy statement here.

Remember to manage sensitive information, such as IAM policies and other credentials, with care, using strategies such as Pulumi's secret management or other means to keep your infrastructure secure.