README.md

secretsmanager-sidecar

A simple command line program designed to be run as a sidecar container that writes a secret from AWS SecretsManager to a file.

Example usage

# name of secrets manager secret
export SECRET_ID=my-secret

# where the secret should be written
export SECRET_FILE=/var/secret/my-secret

# run the program
./secretsmanager-sidecar

In this example, the program writes the contents of the decrypted secrets manager secret my-secret to /var/secret/my-secret and then exits.

AWS Access

This program uses the AWS SDK for Go which looks for credentials in the following locations:

1. Environment Variables

2. Shared Credentials File

3. EC2 Instance Profile

For more information see Specifying Credentials in the AWS SDK for Go documentation.

Example Usage with Docker

Edit the included example docker-compose.yml or create one filling in your details. This assumes that your AWS credentials are in the ~/.aws/credentials file, so update the environment variables and region accordingly.

services:
  secrets:
    build: .
    image: secretsmanager-sidecar
    volumes:
      - $HOME/.aws/credentials:/root/.aws/credentials:ro
      - $PWD/secret/:/var/secret/
    environment:      
      AWS_PROFILE: <your profile name>
      AWS_REGION: us-east-1
      SECRET_ID: <your secret>
      SECRET_FILE: /var/secret/my-secret

Then use your new docker-compose file:

docker-compose up

You should see a file created in a new secret directory.

Usage with ECS/Fargate

The following ECS task definition container definitions configure a sidecar that runs this program and then after it exits with a code of 0, starts the app container which will have access to the secret file.

[
  {
    "name": "app",
    "image": "ghcr.io/warnermedia/fargate-default-backend:v0.9.0",
    "essential": true,
    "dependsOn": [
      {
        "containerName": "secrets",
        "condition": "SUCCESS"
      }
    ],
    "portMappings": [
      {
        "protocol": "tcp",
        "containerPort": 8080,
        "hostPort": 8080
      }
    ],
    "environment": [
      {
        "name": "SECRET",
        "value": "/var/secret/my-secret"
      }
    ],
    "mountPoints": [
      {
        "readOnly": true,
        "containerPath": "/var/secret",
        "sourceVolume": "secret"
      }
    ],    
    "logConfiguration": {
      "logDriver": "awslogs",
      "options": {
        "awslogs-group": "/fargate/service/myapp",
        "awslogs-region": "us-east-1",
        "awslogs-stream-prefix": "ecs"
      }
    }
  },
  {
    "name": "secrets",
    "image": "<your hosted repo>/secretsmanager-sidecar:1.0.0",
    "essential": false,
    "environment": [
      {
        "name": "SECRET_ID",
        "value": "my-secret"
      },
      {
        "name": "SECRET_FILE",
        "value": "/var/secret/my-secret"
      }
    ],
    "mountPoints": [
      {
        "readOnly": false,
        "containerPath": "/var/secret",
        "sourceVolume": "secret"
      }
    ],    
    "logConfiguration": {
      "logDriver": "awslogs",
      "options": {
        "awslogs-group": "/fargate/service/myapp",
        "awslogs-region": "us-east-1",
        "awslogs-stream-prefix": "ecs"
      }
    }
  }  
]