Merritt Admin Sinatra

This lambda is part of the Merritt Preservation System.

Purpose

This web application allows members of the Merritt Team to manage the Merritt Digital Preservation System.

• Ruby Docs

Application Framework

This application is built on the sinatra framework.

• HTTP requests are made to the application
• Requests are matched to a "route"

Sinatra apps are typically run inside a puma webserver using rack.

Application Configuration

• Merritt Admin Rack Config
  • Initialization Code
• Main Acct Rack Config
  • Initialization Code

Merritt Admin Tool Framework

• Request handling utilizes an admin tool client to satisify the request
  • query client: queries the Merritt inventory and billing databases
  • zookeeper client: queries the Merritt queuing system
  • ldap client: queries the Merritt user permission directory
  • code client: queries GitHub, CodeArtifact and Elastic Container Registry for information about Merritt code
• Response are returned to the user
  • some responses are returned to the user in JSON format
  • most responses are returned in the user as HTML, preferable containing a table of data

Merritt Admin Tool Config Files

Menu File

The menu system for the Merritt Admin Tool is configured in a yaml file: menu.yml.

The hierarchy of the menu entries is used to generate breadcrumbs for each page that is displayed in the application.

Lookup Files

Merritt configuration is resloved using a lookup file.

The top level keys of the yaml file allow different application configurations to be defined (ecs-prd, ecs-dev, docker).

Lookup values can be resolved in 3 ways

• ssm: ssm lookup, note that this is not appropriate for a docker compose stack
• env: env lookup
• val: hard coded

When running in docker-compose, most values are resolved to a simple hard-coded value.

Query Files

• All of the SQL run by the Merritt Admin Tool is defined in a query yaml file.
• Where possible, the keys within the yaml file match the route paths for the application.
• To reduce code repetition, some queries are assembled using mustache templates
• Some query columns have a special properties that are tied to the column name
  • these properties are used to format the column, to create hyperlinks, and to assign CSS classes
• Other queries have a special query resolver that can combine columns or generate action buttons
• The Query definitions map named url parameters to positional parameters in an SQL prepared statement
• A query definition might contain a markdown section that defines the purpose of a particular query

Admin Tool Deployments

• This application is deployed as a web applications to the 5 Merritt ECS stacks.
  • Merritt team members must authenticate with AWS cognito to access the application.
• This application can be run on a developer desktop using docker-compose.
• A pared down version of this application is also deployed to the CDL "main account" as a lambda.
  • Merritt team members must authenticate with AWS cognito to access the application.
  • Because of the mysql dependency within the application, the lambda code is deployed as a docker image.

Local Testing

The Merritt Admin tool can be run as a standalone ruby application although the standalone application will not be able to connect to other Merritt microservices.

Merritt app

MERRITT_ECS=desktop bundle exec puma app/config_mrt.ru

UC3-focuesed app

MERRITT_ECS=desktop bundle exec puma app/config_uc3.ru