RealtimeSigns

Here's a general overview of the realtime_signs (RTS) application which should be helpful for getting oriented to how things work. Please keep this up to date -- if you change something major in the code (build process, renaming modules, significant functionality changes, new configuration, etc.) document it here!

Prerequisites

• asdf
• direnv

Development

• If it's your first time using asdf, run asdf plugin add erlang && asdf plugin add elixir.
• Run asdf install from the repository root.
• mix deps.get to fetch dependencies.
• At this point you should be able to run mix test and get a clean build.
• Copy .envrc.template to .envrc, then edit .envrc and make sure all required environment variables are set. When finished, run direnv allow to activate them.
• To start the server, run mix run --no-halt.

Developing locally with signs_ui

First, ensure you have a basic working environment as described above, and in the signs_ui README.

1. Start signs_ui and tell it what API key to accept: MESSAGES_API_KEYS=realtime_signs:a6975e41192b888c NODE_ENV=development mix run --no-halt. The key is arbitrary but it must match what you provide in the next step.
2. Edit .envrc and ensure that SIGN_UI_URL, SIGN_UI_API_KEY, and SIGN_CONFIG_FILE are configured to point to the local signs_ui.
3. Start realtime_signs.
4. Open up http://localhost:5000 and you should see the signs data being populated by your local app.

Environment variables

The application needs several environment variables to access external services. See .envrc.template for documentation. When running locally, these variables are provided by direnv. In deployed environments, they are provided by AWS Secrets Manager. When adding new environment variables, make sure to add them to both locations, as appropriate.

Deploying

Realtime Signs runs on on-prem servers. Deployments are managed with ECS Anywhere, which allows us to manage RTS deployments on those on-prem servers. Deployments are initiated through the following GitHub Actions:

• Deploy to Dev Green
• Deploy to Dev
• Deploy to Prod

Deployment actions require the following repository secrets to be set in GitHub:

AWS_ROLE_ARN
DOCKER_REPO (the ECR repository to push images into)
SLACK_WEBHOOK