Introduction

We use the AWS Cloud Development Kit (CDK) to deploy this Trello Backup application to AWS.

The enumerateBoards Lambda function runs on a schedule and iterates over the Trello boards accessible to the user identified by the TRELLO_KEY and TRELLO_TOKEN. It publishes a message about each board using the Simple Notification Service (SNS).

The backupBoard Lambda function subscribes to the messages published by enumerateBoards and, for each Trello board, downloads the recent data from that board and stores the data to an S3 bucket.

The checkBoardBackups Lambda function is scheduled to run after we expect the backup to have completed and checks that the backups have been created as expected. It updates our monitoring service (healthchecks.io) with the success or failure of the backup job. It additionally sends us an email if the backup failed.

Requirements

• bash
• node
• npm
• ruby
• bundler

Setup

Install ruby

rbenv install

NOTE. If you're not using rbenv then be sure to install the version in .ruby-version.

Install node

nvm install

NOTE. If you're not using nvm then be sure to install the version in .nvmrc.

Install node packages

npm ci

Configure AWS

You need the credentials of an AWS IAM user that has permission to create, modify and delete all the AWS resources used in this CDK application.

aws configure

Getting a Trello API key

NOTE. If you're modifying an existing stack then you'll want to get the existing value from the deployed version. See the section on Environment Variables below for more information.

Ensure you're signed in to Trello as a user with access to the relevant boards.

$ open "https://trello.com/1/appKey/generate"
# Copy the Key (under Developer API Keys) to the clipboard

# Temporarily store the Trello API key in an environment variable
$ export TRELLO_KEY=`pbpaste`

# Store the Trello API key in .env
$ echo "TRELLO_KEY=$TRELLO_KEY" >> .env

Getting a Trello API token

NOTE. If you're modifying an existing stack then you'll want to get the existing value from the deployed version. See the section on Environment Variables below for more information.

Ensure you're signed in to Trello as a user with access to the relevant boards. It's safe to do this step multiple times as you'll get the same token back even if it's already been generated.

$ open "https://trello.com/1/connect?key=$TRELLO_KEY&name=$TRELLO_APP_NAME&expiration=never&response_type=token"
# Allow the Trello backup "app" to read our Trello account

# Copy the token from the resulting page

# Temporarily store the Trello token in an environment variable
$ export TRELLO_TOKEN=`pbpaste`

# Store the Trello token in .env
$ echo "TRELLO_TOKEN=$TRELLO_TOKEN" >> .env

Environment variables

In the .env file, set the following environment variables:

• TRELLO_TOKEN - used in all 3 Lambda functions to authenticate with Trello
• TRELLO_KEY - used in all 3 Lambda functions to authenticate with Trello
• TRELLO_BACKUP_CARD_MODIFIED_SINCE - used in the backupBoard function to query Trello for cards modified since a certain date
• TRELLO_BACKUP_OLDEST_ALLOWED_BACKUP_IN_SECONDS - used by checkBoardBackups to determine whether the latest backup is recent enough e.g. 1800 only allows backups to be 30 minutes old; older backups trigger an error
• HEALTHCHECKS_ENDPOINT_URL - used by checkBoardBackups function to record the success/failure of the function
• TRELLO_BACKUP_MONITORING_EMAIL_ADDRESS - the email address where monitoring emails will be sent (an email will be sent on first deployment to ask you to confirm the subscription)
• TRELLO_BACKUP_SCHEDULE_FOR_BACKUP - specifies how often/when the backup is performed, e.g. cron(0 2 * * ? *) runs daily at 2am (see Schedule Expressions for Rules for details)
• TRELLO_BACKUP_SCHEDULE_FOR_CHECK - specifies how often/when the post-backup check is performed, e.g. cron(30 2 * * ? *) runs daily at 2.30am; should typically be run some time after the backup phase is expected to complete

Retrieving existing values from AWS

If you're modifying an existing CDK application then you'll want to retrieve the values that are being used in production. You can use the aws cli to populate your .env with the production values:

echo "TRELLO_TOKEN=$(aws lambda list-functions | jq '.Functions | .[] | select(.FunctionName | test("TrelloBackupStack-checkBoardBackups")) | .Environment | .Variables | .TRELLO_TOKEN')" >> .env
echo "TRELLO_KEY=$(aws lambda list-functions | jq '.Functions | .[] | select(.FunctionName | test("TrelloBackupStack-checkBoardBackups")) | .Environment | .Variables | .TRELLO_KEY')" >> .env
echo "TRELLO_BACKUP_CARD_MODIFIED_SINCE=$(aws lambda list-functions | jq '.Functions | .[] | select(.FunctionName | test("TrelloBackupStack-backupBoard")) | .Environment | .Variables | .TRELLO_BACKUP_CARD_MODIFIED_SINCE')" >> .env
echo "TRELLO_BACKUP_OLDEST_ALLOWED_BACKUP_IN_SECONDS=$(aws lambda list-functions | jq '.Functions | .[] | select(.FunctionName | test("TrelloBackupStack-checkBoardBackups")) | .Environment | .Variables | .TRELLO_BACKUP_OLDEST_ALLOWED_BACKUP_IN_SECONDS')" >> .env
echo "HEALTHCHECKS_ENDPOINT_URL=$(aws lambda list-functions | jq '.Functions | .[] | select(.FunctionName | test("TrelloBackupStack-checkBoardBackups")) | .Environment | .Variables | .HEALTHCHECKS_ENDPOINT_URL')" >> .env
echo "TRELLO_BACKUP_MONITORING_EMAIL_ADDRESS=$(aws sns list-subscriptions | jq '.Subscriptions | .[] | select(.SubscriptionArn | test("TrelloBackupStack-monitoringTopic")) | .Endpoint')" >> .env
echo "TRELLO_BACKUP_SCHEDULE_FOR_BACKUP=$(aws events list-rules | jq '.Rules | .[] | select(.Name | test("TrelloBackupStack-RuleForBackup")) | .ScheduleExpression')" >> .env
echo "TRELLO_BACKUP_SCHEDULE_FOR_CHECK=$(aws events list-rules | jq '.Rules | .[] | select(.Name | test("TrelloBackupStack-RuleForCheck")) | .ScheduleExpression')" >> .env

Build

npm run build

Compare the local version to production

npx cdk diff

Deploy the application

npx cdk deploy

Execute CDK commands

cdk --profile <aws-profile-name> <cdk-command>

• See Command-line Toolkit for a list of commands and options to use with the cdk command-line tool.

• The cdk.json file defines an appropriate value for the --app option, so there is no need to specify this unless you want to override that value.

• When a stack uses assets (e.g. via a call to aws-lambda.Code.asset()), before using the cdk command-line tool to deploy to an AWS environment for the first time, the environment must be bootstrapped using: cdk bootstrap.