Deploy Flagsmith on AWS using CloudFormation

In this post, we'll deploy Flagsmith on AWS using CloudFormation. Flagsmith is an open-source feature flag and remote configuration service. It allows you to manage feature flags and remote configuration for your applications.

What are feature flags?

Feature flags, also known as feature toggles, are a software development practice that allows teams to modify system behavior without changing code. They act as switches that can turn features on or off in a live environment, providing a high level of control over a software's functionality.

Imagine a light switch in your home; you can easily turn the lights on or off without rewiring the electrical system. Similarly, feature flags enable developers to toggle features for users without deploying new code. This approach is especially useful for testing new features, performing A/B testing, or enabling a gradual rollout to users.

At their core, feature flags are implemented through conditional statements in the code that check the status of a flag. If the flag is active, the new feature is presented to the user; if not, the system defaults to the existing functionality. The status of these flags is typically controlled through a feature management system that can be updated in real-time.

Example use cases for feature flags include:

• Testing in Production: Feature flags allow developers to test new features in the production environment with a subset of users. This is known as canary releasing. By exposing the feature to a small group, you can gather valuable feedback and ensure stability before a wider release.
• Gradual Rollouts: Instead of launching a feature to all users at once, feature flags enable a gradual rollout. This helps in monitoring the feature's impact on system performance and user experience, and quickly rolling it back if issues arise.
• User Segmentation: Feature flags can be used to enable features for specific user segments. For example, you might roll out a new feature only to premium users or to users in a particular geographic location.
• A/B Testing: By employing feature flags, teams can perform A/B testing to compare different user experiences and determine which version performs better in terms of user engagement, conversion rates, and other metrics.
• Emergency Kill Switch: If a newly released feature causes unexpected issues, feature flags serve as an emergency kill switch. Developers can quickly disable the problematic feature, mitigating any negative impact on the user experience.

Architecture

We'll deploy Flagsmith on AWS using a CloudFormation. The architecture consists of the following components:

• Amazon Certificate Manager: We'll use ACM to provision SSL/TLS certificates for securing the application's traffic.
• Amazon Route 53: We'll use Route 53 to manage the DNS records for the application's domain name.
• Amazon RDS (Relational Database Service): We'll use RDS to host the PostgreSQL database for storing feature flags and configuration data. We are using RDS PostgreSQL Cluster with Multi-AZ deployment for high availability and fault tolerance, deployed in private subnets.
• Amazon Application Load Balancer: We'll use an ALB to route incoming traffic to the ECS service. The ALB will be configured with a listener for HTTPS traffic, deployed in a public subnet.
• Flagsmith API: The Flagsmith API is a RESTful service that provides endpoints for managing feature flags and configurations. This service is deployed as a Docker container on ECS in a private subnet.
• Flagsmith Processor: The Flagsmith Processor is a background worker that processes feature flag evaluations and updates the database. This service is also deployed as a Docker container on ECS in a private subnet, subscribing to events from the RDS database.
• Auto-scaling: Both the API and Processor services are deployed as ECS tasks behind an Application Load Balancer. The ECS service is configured to auto-scale based on CPU utilization.

The following diagram illustrates the architecture:

Now, let's deploy Flagsmith on AWS using CloudFormation.

Prerequisites

Before we begin, make sure you have the following prerequisites:

• An AWS account with the necessary permissions to create resources using CloudFormation.
• The AWS CLI installed and configured with your AWS account credentials.

Deployment Steps

Elastic Container Registry (ECR)

We must begin by creating an ECR repository for the Flagsmith Docker image. We need to do this in order to avoid throttling issues when pulling the image from Docker Hub.

Type the following command in your terminal to create the ECR repository:

aws ecr create-repository --repository-name flagsmith

warning

The following build command must be run on an X86 system. If you are using an M1 Mac, you can use a virtual machine to run the command.

Let's pull the flagsmith image from Docker Hub:

docker pull flagsmith/flagsmith:latest

Tag the image with the ECR repository URI:

docker push {account-id}.dkr.ecr.us-east-1.amazonaws.com/flagsmith:latest

info

Replace {account-id} with your AWS account ID and us-east-1 with your preferred AWS region.

Login to ECR:

aws ecr get-login-password --region us-east-1 | docker login --username AWS --password-stdin {account-id}.dkr.ecr.us-east-1.amazonaws.com

And finally, push the image to ECR:

docker push {account-id}.dkr.ecr.us-east-1.amazonaws.com/flagsmith:latest

Great! We have successfully mirrored the flagsmith image on ECR. Now, let's deploy the CloudFormation template.

CloudFormation

Create a new file named stack-params.json with the following content:

[
    {
        "ParameterKey": "AllowedHosts",
        "ParameterValue": "*"
    },
    {
        "ParameterKey": "DatabasePassword",
        "ParameterValue": "{password}"
    },
    {
        "ParameterKey": "DatabasePort",
        "ParameterValue": "5432"
    },
    {
        "ParameterKey": "FlagsmithImage",
        "ParameterValue": "{account-id}.dkr.ecr.us-east-1.amazonaws.com/flagsmith:latest"
    },
    {
        "ParameterKey": "FlagsmithServiceSize",
        "ParameterValue": "1"
    },
    {
        "ParameterKey": "ServiceName",
        "ParameterValue": "flagsmith"
    },
    {
        "ParameterKey": "StageName",
        "ParameterValue": "prod"
    },
    {
        "ParameterKey": "ApexDomain",
        "ParameterValue": "{domain.tld}"
    },
    {
        "ParameterKey": "SendgridApiKey",
        "ParameterValue": "{api-key}"
    }
]

Replace the placeholders with the appropriate values:

• {password}: A strong password for the RDS database.
• {account-id}: Your AWS account ID.
• {domain.tld}: Your domain name.
• {api-key}: Your SendGrid API key.

The CloudFormation template

Create a new file named cloudformation.yml with the following content:

AWSTemplateFormatVersion: '2010-09-09'
Description: CloudFormation template for Flagsmith Platform

Parameters:
  ApexDomain:
    Description: The domain name for the Flagsmith Platform (e.g., "example.com")
    Type: String
    Default: example.com
  StageName:
    Description: The environment for the Flagsmith Platform (e.g., "prod")
    Type: String
    Default: prod
    AllowedValues:
      - dev
      - prod
      - staging
  ServiceName:
    Description: "Service name"
    Type: String
    Default: "flagsmith"
  AllowedHosts:
    Type: String
    Description: Django allowed hosts (e.g., "*")
    Default: "*"
  DatabasePassword:
    Type: String
    Description: Password for the PostgreSQL database
    NoEcho: True
  DatabasePort:
    Type: Number
    Description: Port for the PostgreSQL database
    Default: 3306
  FlagsmithImage:
    Type: String
    Description: Docker image for the Flagsmith service
    Default: flagsmith/flagsmith:latest
  FlagsmithServiceSize:
    Type: Number
    Description: Number of ECS tasks to run for the Flagsmith service
    Default: 1
  SendgridApiKey:
    Type: String
    Description: API key for Sendgrid
    NoEcho: True
    Default: ""
  EnableAdminPasswordAccess:
    Type: String
    Description: Enable admin password access
    Default: "False"
    AllowedValues:
      - "True"
      - "False"

Conditions:
  CreateProdResources: !Equals
    - !Ref StageName
    - prod
  CreateDevResources: !Not
    - !Equals
      - !Ref StageName
      - prod

Resources:
  #
  # CloudWatch Logs
  #
  CloudWatchLogsGroup:
    Type: AWS::Logs::LogGroup
    Properties:
      LogGroupName: !Ref AWS::StackName
      RetentionInDays: 365
  
  #
  # TLS Certificate
  #
  FlagsmithCertificate:
    Type: AWS::CertificateManager::Certificate
    Properties:
      DomainName: !Sub flagsmith.${ApexDomain}
      ValidationMethod: DNS
      DomainValidationOptions:
        - DomainName: !Sub flagsmith.${ApexDomain}
          ValidationDomain: !Sub flagsmith.${ApexDomain}

  #
  # ALB Target Group and Listener Rules
  #
  LoadBalancer:
    Type: AWS::ElasticLoadBalancingV2::LoadBalancer
    Properties:
      Name: !Sub ${AWS::StackName}
      Scheme: internet-facing
      Subnets:
        - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PublicSubnet1" ] ] }
        - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PublicSubnet2" ] ] }
        - !If
          - CreateProdResources
          - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PublicSubnet3" ] ] }
          - !Ref AWS::NoValue
        - !If
          - CreateProdResources
          - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PublicSubnet4" ] ] }
          - !Ref AWS::NoValue
      SecurityGroups:
        - { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "LoadBalancerSecurityGroup" ] ] }
      LoadBalancerAttributes:
        - Key: idle_timeout.timeout_seconds
          Value: 60
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName
  LoadBalancerListener:
    Type: AWS::ElasticLoadBalancingV2::Listener
    Properties:
      LoadBalancerArn: !Ref LoadBalancer
      Port: 80
      Protocol: HTTP
      DefaultActions:
        - Type: redirect
          RedirectConfig:
            Protocol: "HTTPS"
            Port: "443"
            Host: "#{host}"
            Path: "/#{path}"
            Query: "#{query}"
            StatusCode: "HTTP_301"
  LoadBalancerSecureListener:
    Type: AWS::ElasticLoadBalancingV2::Listener
    Properties:
      LoadBalancerArn: !Ref LoadBalancer
      Port: 443
      Protocol: HTTPS
      Certificates:
        - CertificateArn: !Ref FlagsmithCertificate
      DefaultActions:
        - Type: forward
          TargetGroupArn: !Ref DefaultTargetGroup
  DefaultTargetGroup:
    Type: AWS::ElasticLoadBalancingV2::TargetGroup
    Properties:
      Name: !Sub ${AWS::StackName}-1
      VpcId: { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "VPC" ] ] }
      Port: 80
      Protocol: HTTP
  TargetGroup:
    Type: AWS::ElasticLoadBalancingV2::TargetGroup
    DependsOn: LoadBalancer
    Properties:
      Name: !Sub ${AWS::StackName}-2
      VpcId: { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "VPC" ] ] }
      Port: 80
      Protocol: HTTP
      Matcher:
        HttpCode: 200-299
      HealthCheckIntervalSeconds: 30
      HealthCheckPath: /health
      HealthCheckProtocol: HTTP
      HealthCheckTimeoutSeconds: 5
      HealthyThresholdCount: 2
      UnhealthyThresholdCount: 6
      TargetType: ip
      TargetGroupAttributes:
        - Key: deregistration_delay.timeout_seconds
          Value: 120
  ListenerRuleSecure:
    Type: AWS::ElasticLoadBalancingV2::ListenerRule
    Properties:
      ListenerArn: !Ref LoadBalancerSecureListener
      Priority: 5
      Conditions:
        - Field: path-pattern
          Values:
            - "/*"
      Actions:
        - TargetGroupArn: !Ref TargetGroup
          Type: forward
  ListenerRule:
    Type: AWS::ElasticLoadBalancingV2::ListenerRule
    Properties:
      ListenerArn: !Ref LoadBalancerListener
      Priority: 5
      Conditions:
        - Field: path-pattern
          Values:
            - "/*"
      Actions:
        - TargetGroupArn: !Ref TargetGroup
          Type: forward

  #
  # Roles
  #
  TaskExecutionRole:
    Type: AWS::IAM::Role
    Properties:
      Path: /
      RoleName: !Sub ${AWS::StackName}-task-exec-role-${AWS::Region}
      ManagedPolicyArns:
        - 'arn:aws:iam::aws:policy/service-role/AmazonEC2ContainerServiceAutoscaleRole'
      AssumeRolePolicyDocument: |
        {
            "Statement": [{
                "Action": "sts:AssumeRole",
                "Effect": "Allow",
                "Principal": {
                    "Service": "ecs-tasks.amazonaws.com"
                }
            }]
        }
      Policies:
        - PolicyName: !Sub ${AWS::StackName}-task-exec-policy-${AWS::Region}
          PolicyDocument:
            Version: "2012-10-17"
            Statement:
              - Effect: Allow
                Resource: "*"
                Action:
                  - logs:CreateLogStream
                  - logs:CreateLogGroup
                  - logs:PutLogEvents
                  - logs:DescribeLogStreams
                  - ecr:GetDownloadUrlForLayer
                  - ecr:GetAuthorizationToken
                  - ecr:BatchCheckLayerAvailability
                  - ecr:GetRepositoryPolicy
                  - ecr:BatchGetImage
                  - ecs:ListClusters
                  - ecs:ListContainerInstances
                  - ecs:DescribeContainerInstances
              - Effect: Allow
                Resource: !Join [ "", [ "arn:aws:s3:::", { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "AutohostBucket" ] ] }, "/", !Ref StageName, ".env" ] ]
                Action:
                  - s3:GetObject
              - Effect: Allow
                Resource: !Join [ "", [ "arn:aws:s3:::", { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "AutohostBucket" ] ] } ] ]
                Action:
                  - s3:GetBucketLocation

  TaskRole:
    Type: AWS::IAM::Role
    Properties:
      RoleName: !Sub ${AWS::StackName}-${AWS::Region}
      Path: /
      AssumeRolePolicyDocument: |
        {
            "Statement": [{
                "Action": "sts:AssumeRole",
                "Effect": "Allow",
                "Principal": {
                    "Service": "ecs-tasks.amazonaws.com"
                }
            }]
        }
      Policies:
        - PolicyName: !Sub ${AWS::StackName}-${AWS::Region}
          PolicyDocument:
            {
              "Statement": [ {
                "Effect": "Allow",
                "Action": [
                  "iam:PassRole",
                  "ssmmessages:CreateControlChannel",
                  "ssmmessages:CreateDataChannel",
                  "ssmmessages:OpenControlChannel",
                  "ssmmessages:OpenDataChannel"
                ],
                "Resource": "*"
              },
              {
                "Effect": "Allow",
                "Action": [
                  "dynamodb:*",
                ],
                "Resource": [
                  { "Fn::GetAtt": [ "EnvironmentsTable", "Arn" ] },
                  { "Fn::GetAtt": [ "IdentitiesTable", "Arn" ] }
                ]
              } ]
            }

  #
  # RDS subnets, security group, and cluster
  #
  PostgresSecurityGroup:
    Type: AWS::EC2::SecurityGroup
    Properties:
      GroupDescription: Security group for the PostgreSQL instance
      VpcId: { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "VPC" ] ] }
      SecurityGroupIngress:
        - IpProtocol: tcp
          FromPort: !Ref DatabasePort
          ToPort: !Ref DatabasePort
          SourceSecurityGroupId: { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "FargateContainerSecurityGroup" ] ] }
        - IpProtocol: "-1"
          SourceSecurityGroupId: { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "FargateContainerSecurityGroup" ] ] }
      SecurityGroupEgress:
        - IpProtocol: "-1"
          CidrIp: "0.0.0.0/0"
  PostgresSubnetGroup:
    Type: AWS::RDS::DBSubnetGroup
    Properties:
      DBSubnetGroupDescription: Subnets available for the Flagsmith PostgreSQL instance
      DBSubnetGroupName: !Sub ${AWS::StackName}
      SubnetIds:
        - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet1" ] ] }
        - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet2" ] ] }
        - !If
          - CreateProdResources
          - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet3" ] ] }
          - !Ref AWS::NoValue
        - !If
          - CreateProdResources
          - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet4" ] ] }
          - !Ref AWS::NoValue
  PostgresCluster:
    Type: AWS::RDS::DBInstance
    Condition: CreateProdResources
    DependsOn:
      - PostgresSecurityGroup
    Properties:
      DBInstanceIdentifier: !Sub ${AWS::StackName}
      DBInstanceClass: db.t3.medium
      DBName: flagsmith
      Engine: postgres
      EngineVersion: "15.3"
      Port: !Ref DatabasePort
      AllocatedStorage: 40
      StorageType: gp2
      StorageEncrypted: true
      MasterUsername: postgres
      MasterUserPassword: !Ref DatabasePassword
      DBSubnetGroupName: !Ref PostgresSubnetGroup
      VPCSecurityGroups:
        - !Ref PostgresSecurityGroup
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName
  PostgresInstance:
    Type: AWS::RDS::DBInstance
    Condition: CreateDevResources
    DependsOn:
      - PostgresSecurityGroup
    Properties:
      DBInstanceIdentifier: !Sub ${AWS::StackName}
      DBInstanceClass: db.t3.medium
      DBName: flagsmith
      Engine: postgres
      EngineVersion: "15.3"
      Port: !Ref DatabasePort
      AllocatedStorage: 20
      StorageType: gp2
      StorageEncrypted: true
      MasterUsername: postgres
      MasterUserPassword: !Ref DatabasePassword
      DBSubnetGroupName: !Ref PostgresSubnetGroup
      VPCSecurityGroups:
        - !Ref PostgresSecurityGroup
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName

  #
  # DynamoDB Tables
  #
  EnvironmentsTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: !Sub "${AWS::StackName}-environments"
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      BillingMode: PAY_PER_REQUEST
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName
  IdentitiesTable:
    Type: AWS::DynamoDB::Table
    Properties:
      TableName: !Sub "${AWS::StackName}-identities"
      AttributeDefinitions:
        - AttributeName: id
          AttributeType: S
      KeySchema:
        - AttributeName: id
          KeyType: HASH
      BillingMode: PAY_PER_REQUEST
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName

  #
  # Service Discovery
  #
  FlagsmithDiscoveryService:
    Type: AWS::ServiceDiscovery::Service
    Properties:
      Name: !Sub ${AWS::StackName}
      DnsConfig:
        DnsRecords: [ { Type: A, TTL: "10" } ]
        NamespaceId: { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "ServiceDiscoveryNamespaceId" ] ] }

  #
  # ECS Services
  #
  FlagsmithService:
    Type: AWS::ECS::Service
    DependsOn:
      - TargetGroup
      - ListenerRuleSecure
    Properties:
      LaunchType: FARGATE
      Cluster: { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "ECSClusterArn" ] ] }
      DesiredCount: !Ref FlagsmithServiceSize
      TaskDefinition: !Ref FlagsmithTaskDefinition
      EnableExecuteCommand: true
      NetworkConfiguration:
        AwsvpcConfiguration:
          AssignPublicIp: DISABLED
          SecurityGroups:
            - { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "FargateContainerSecurityGroup" ] ] }
          Subnets:
            - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet1" ] ] }
            - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet2" ] ] }
            - !If
              - CreateProdResources
              - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet3" ] ] }
              - !Ref AWS::NoValue
            - !If
              - CreateProdResources
              - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet4" ] ] }
              - !Ref AWS::NoValue
      DeploymentConfiguration:
        MaximumPercent: 200
        MinimumHealthyPercent: 75
      LoadBalancers:
        - ContainerName: "flagsmith"
          ContainerPort: 8000
          TargetGroupArn: !Ref TargetGroup
      ServiceRegistries:
        - RegistryArn: !GetAtt FlagsmithDiscoveryService.Arn
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName
  FlagsmithTaskDefinition:
    Type: AWS::ECS::TaskDefinition
    DependsOn:
      - TargetGroup
      - ListenerRuleSecure
    Properties:
      Family: Flagsmith
      ExecutionRoleArn: !Ref TaskExecutionRole
      TaskRoleArn: !Ref TaskRole
      NetworkMode: awsvpc
      Memory: 2048
      Cpu: 1024
      RequiresCompatibilities:
        - FARGATE
      ContainerDefinitions:
        - Name: flagsmith
          Essential: true
          Image: !Ref FlagsmithImage
          Environment:
            - Name: AWS_REGION
              Value: !Ref AWS::Region
            - Name: ENV
              Value: !Ref StageName
            - !If
              - CreateProdResources
              - Name: ENVIRONMENT
                Value: production
              - Name: ENVIRONMENT
                Value: !Ref StageName
            - Name: STAGE_NAME
              Value: !Ref StageName
            - Name: DJANGO_ALLOWED_HOSTS
              Value: !Ref AllowedHosts
            - !If
              - CreateProdResources
              - Name: DATABASE_URL
                Value: !Sub "postgresql://postgres:${DatabasePassword}@${PostgresCluster.Endpoint.Address}:${DatabasePort}/flagsmith"
              - Name: DATABASE_URL
                Value: !Sub "postgresql://postgres:${DatabasePassword}@${PostgresInstance.Endpoint.Address}:${DatabasePort}/flagsmith"
            - Name: USE_POSTGRES_FOR_ANALYTICS
              Value: "True"
            - Name: DJANGO_SECRET_KEY
              Value: !Ref DatabasePassword
            - Name: USE_X_FORWARDED_HOST
              Value: "True"
            - Name: SENDGRID_API_KEY
              Value: !Ref SendgridApiKey
            - Name: SENDER_EMAIL
              Value: !Sub "noreply@flagsmith.${ApexDomain}"
            - Name: ENABLE_ADMIN_ACCESS_USER_PASS
              Value: !Ref EnableAdminPasswordAccess
            - Name: ENVIRONMENTS_TABLE_NAME_DYNAMO
              Value: !Ref EnvironmentsTable
            - Name: IDENTITIES_TABLE_NAME_DYNAMO
              Value: !Ref IdentitiesTable
            - Name: GUNICORN_KEEP_ALIVE
              Value: "90"
            - Name: DOMAIN_OVERRIDE
              Value: !Sub "flagsmith.${ApexDomain}"
            - Name: CSRF_TRUSTED_ORIGINS
              Value: !Sub "flagsmith.${ApexDomain}"
          Command:
            # Run migrations and then start the server (use 'serve' to skip migrations)
            - migrate-and-serve
          PortMappings:
            - ContainerPort: 8000
          LogConfiguration:
            LogDriver: awslogs
            Options:
              awslogs-group: !Sub ${AWS::StackName}
              awslogs-region: !Ref AWS::Region
              awslogs-stream-prefix: 'service'
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName

  # Autoscaling rules for web service
  FlagsmithAutoscalingTarget:
    Type: AWS::ApplicationAutoScaling::ScalableTarget
    Condition: CreateProdResources
    DependsOn:
      - FlagsmithService
      - TaskExecutionRole
    Properties:
      MinCapacity: !Ref FlagsmithServiceSize
      MaxCapacity: 5
      ResourceId: !Join [ '/', [ service, { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "ECSClusterName" ] ] }, !GetAtt FlagsmithService.Name ] ]
      ScalableDimension: ecs:service:DesiredCount
      ServiceNamespace: ecs
      RoleARN: !GetAtt TaskExecutionRole.Arn
  FlagsmithAutoscalingPolicy:
    Type: AWS::ApplicationAutoScaling::ScalingPolicy
    Condition: CreateProdResources
    DependsOn:
      - FlagsmithService
      - FlagsmithAutoscalingTarget
    Properties:
      PolicyName: !Sub ${AWS::StackName}
      PolicyType: TargetTrackingScaling
      ScalingTargetId: !Ref FlagsmithAutoscalingTarget
      TargetTrackingScalingPolicyConfiguration:
        PredefinedMetricSpecification:
          PredefinedMetricType: ECSServiceAverageCPUUtilization
        ScaleInCooldown: 900
        ScaleOutCooldown: 30
        # Keep things at or lower than 50% CPU utilization
        TargetValue: 75

  # Flagsmith processor service
  FlagsmithProcessorService:
    Type: AWS::ECS::Service
    DependsOn:
      - PostgresSecurityGroup
    Properties:
      LaunchType: FARGATE
      Cluster: { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "ECSClusterArn" ] ] }
      DesiredCount: 1
      TaskDefinition: !Ref FlagsmithProcessorTaskDefinition
      EnableExecuteCommand: true
      NetworkConfiguration:
        AwsvpcConfiguration:
          AssignPublicIp: DISABLED
          SecurityGroups:
            - { "Fn::ImportValue": !Join [ "-", [ "autohost-app", !Ref StageName, "FargateContainerSecurityGroup" ] ] }
          Subnets:
            - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet1" ] ] }
            - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet2" ] ] }
            - !If
              - CreateProdResources
              - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet3" ] ] }
              - !Ref AWS::NoValue
            - !If
              - CreateProdResources
              - { "Fn::ImportValue": !Join [ "-", [ "autohost-resources", !Ref StageName, "PrivateSubnet4" ] ] }
              - !Ref AWS::NoValue
      DeploymentConfiguration:
        MaximumPercent: 200
        MinimumHealthyPercent: 75
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName
  FlagsmithProcessorTaskDefinition:
    Type: AWS::ECS::TaskDefinition
    DependsOn:
      - PostgresSecurityGroup
    Properties:
      Family: FlagsmithProcessor
      ExecutionRoleArn: !Ref TaskExecutionRole
      TaskRoleArn: !Ref TaskRole
      NetworkMode: awsvpc
      Cpu: 512
      Memory: 1024
      RequiresCompatibilities:
        - FARGATE
      ContainerDefinitions:
        - Name: flagsmith_processor
          Image: !Ref FlagsmithImage
          Environment:
            - !If
              - CreateProdResources
              - Name: DATABASE_URL
                Value: !Sub "postgresql://postgres:${DatabasePassword}@${PostgresCluster.Endpoint.Address}:${DatabasePort}/flagsmith"
              - Name: DATABASE_URL
                Value: !Sub "postgresql://postgres:${DatabasePassword}@${PostgresInstance.Endpoint.Address}:${DatabasePort}/flagsmith"
            - Name: USE_POSTGRES_FOR_ANALYTICS
              Value: "True"
            - Name: DJANGO_SECRET_KEY
              Value: !Ref DatabasePassword
            - Name: USE_X_FORWARDED_HOST
              Value: "True"
            - Name: SENDGRID_API_KEY
              Value: !Ref SendgridApiKey
            - Name: SENDER_EMAIL
              Value: !Sub "noreply@flagsmith.${ApexDomain}"
            - Name: ENABLE_ADMIN_ACCESS_USER_PASS
              Value: !Ref EnableAdminPasswordAccess
            - Name: ENVIRONMENTS_TABLE_NAME_DYNAMO
              Value: !Ref EnvironmentsTable
            - Name: IDENTITIES_TABLE_NAME_DYNAMO
              Value: !Ref IdentitiesTable
            - Name: DOMAIN_OVERRIDE
              Value: !Sub "flagsmith.${ApexDomain}"
            - Name: CSRF_TRUSTED_ORIGINS
              Value: !Sub "flagsmith.${ApexDomain}"
            - !If
              - CreateProdResources
              - Name: ENVIRONMENT
                Value: production
              - Name: ENVIRONMENT
                Value: !Ref StageName

          Command:
            - run-task-processor
          LogConfiguration:
            LogDriver: awslogs
            Options:
              awslogs-group: !Sub ${AWS::StackName}
              awslogs-region: !Ref AWS::Region
              awslogs-stream-prefix: 'service'
      Tags:
        - Key: service
          Value: !Ref ServiceName
        - Key: Environment
          Value: !Ref StageName

  #
  # Route 53
  #
  DNS:
    Type: AWS::Route53::RecordSetGroup
    Properties:
      HostedZoneName: !Sub ${ApexDomain}.
      RecordSets:
        - Name: !Sub flagsmith.${ApexDomain}
          Type: A
          AliasTarget:
            HostedZoneId: !GetAtt LoadBalancer.CanonicalHostedZoneID
            DNSName: !GetAtt LoadBalancer.DNSName

Outputs:
  FlagsmithServiceUrl:
    Description: URL for accessing the Flagsmith service
    Value: !Sub "https://flagsmith.${ApexDomain}"
    Export:
      Name: !Sub ${AWS::StackName}-ServiceUrl

This CloudFormation template creates the necessary resources for deploying Flagsmith on AWS, including the RDS database, ECS services, ALB, Route 53 records, and more.

warning

This template makes use of the autohost CloudFormation stack outputs that define the VPC, subnets, and security groups. You must replace these references with your own VPC and subnet IDs.

tip

You can use tools such as ChatGPT to replace imported values with your own VPC and subnet IDs, or create the missing resources.

Now, deploy the CloudFormation stack using the following command:

aws cloudformation create-stack \
    --stack-name flagsmith \
    --capabilities CAPABILITY_NAMED_IAM \
    --tags Key=service,Value=flagsmith Key=environment,Value=dev \
    --parameters file://$(pwd)/stack-params.json \
    --template-body file://$(pwd)/cloudformation.yml \
    --profile default

After the stack is created, you can access the Flagsmith service using the URL provided in the CloudFormation stack outputs.

Retrieve the API URL:

aws cloudformation describe-stacks \
    --stack-name flagsmith \
    --query "Stacks[].Outputs[?OutputKey=='ServiceUrl'][] | [0].OutputValue"

You can now access the Flagsmith service using the URL provided.

When you access the URL, you should see the Flagsmith login page.

Usage

To start using Flagsmith, you need to create an account and log in. Once logged in, you can create feature flags, manage user segments, and more.

You can use this sample code to create an API client for Flagsmith:

import Flagsmith from 'flagsmith-nodejs';

/**
 * Export the Flagsmith client
 */

let flagsmithInstance = null;
export const client = () => {
    if (flagsmithInstance) {
        return flagsmithInstance;
    }

    if (!process.env.FLAGSMITH_ENVIRONMENT_KEY || !process.env.FLAGSMITH_API_URL) {
        console.log('WARNING: Flagsmith environment key or API URL is missing');
        return null;
    } else {
        // initialize Flagsmith client
        flagsmithInstance = new Flagsmith({
            environmentKey: process.env.FLAGSMITH_ENVIRONMENT_KEY,
            apiUrl: process.env.FLAGSMITH_API_URL,
        });

        return flagsmithInstance;
    }
};

export const isKeyConfigured = () => {
    return !!process.env.FLAGSMITH_ENVIRONMENT_KEY || !!process.env.FLAGSMITH_API_URL;
};

The expected environment variables are:

• FLAGSMITH_ENVIRONMENT_KEY: The environment key for Flagsmith.
• FLAGSMITH_API_URL: The API URL for the Flagsmith service (e.g., https://flagsmith.example.com/api/v1/).

Conclusion

In this tutorial, we deployed Flagsmith on AWS using CloudFormation. We created an ECR repository for the Flagsmith Docker image, and then deployed the CloudFormation stack to create the necessary resources for running the Flagsmith service. We also retrieved the API URL to access the Flagsmith service. You can now start using Flagsmith to manage feature flags and configurations for your applications.

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