Skate
Skate is a web-based dispatch tool for bus inspectors, built by the MBTA. Imagine an app that helps you track the one bus you want to catch, but instead it’s helping us track all the buses that everyone wants to catch! It has the rich location data driving our mbta.com and rider apps, but also info that matters for keeping things running smoothly (operator names, bus numbers, shift schedules). For background, read our “Skate: Building a better bus dispatch app (and how it will improve your ride)” blog post.
Community
The MBTA Customer Technology Department supports a shared Slack channel that transit agencies and partners adapting the Skate code can use to collaborate and ask questions. To be invited to the Slack channel, email [email protected].
Setup
Prerequisites
Doing development on Skate requires Elixir, Erlang, and node, as described in .tool-versions. Most developers use asdf to help manage the required versions, but that isn't required.
Skate also requires Postgres. If you don't already have Postgres installed, and you're on a Mac, Postgres.app is an easy way to get started. However, any Postgres instance to which you can connect and in which you have sufficient privileges should work.
Configuring to run in a new environment
There are a number of configuration details defined in environment variables. These define where data sources live, as well as authentication and CDN details. In our AWS environments these are all set and managed via Terraform.
To avoid having to set these manually in your local development environment, direnv is strongly recommended. A .envrc.template
file is provided to fill out; simply copy it over to .envrc
and fill in the values, then follow the direnv documentation to load it.
The environment variables are documented in the Skate .envrc.template
file.
Here are the values you'll need to be prepared to update to run Skate locally:
- Your local Postgres server username and password
- Your personal API key from MBTA Realtime API; request one if you don't have one
- API key from Swiftly Transitime API
Quick Setup
- Install language dependencies with
asdf install
- Setup project with
mix setup
- This command will create the database, so you must first ensure your Postgres server is running and you've updated your credentials in
.envrc
as described in "Configuration" above.
- This command will create the database, so you must first ensure your Postgres server is running and you've updated your credentials in
- (not necessary to run the application)
- The
test
command will automatically setup the database when run. - You can setup the the testing database manually by running
mix ecto.setup
in thetest
envrionment specified viaMIX_ENV
$ MIX_ENV=test mix ecto.setup
- The
Updating
After updating merged changes or checking out a new branch (e.g. to test a new feature), you may need to do the following to update the dependencies:
- Update Elixir and Node.js dependencies at the same time by rerunning
mix setup
OR
Update them independently with the following commands
- Update Elixir dependencies with
mix deps.get
- Install Node.js dependencies with
cd assets && npm ci
Running the application
- Start Phoenix endpoint with
mix phx.server
- Visit
localhost:4000
from your browser.
If you see the “data outage” banner when you open your local version of Skate, it means the software can’t get certain info, like crowding, which you need to be on the MBTA network for. Most features would work locally without network access.
Running tests
- Run Elixir tests with
mix test
- Run Javascript tests with
cd assets && npm test
Browser Support Policy
We strive to support all users – but the variety of browsers, operating systems and devices available necessitates a more intentioned approach. These differences could potentially cause bugs and harm your experience with Skate. Ensure you have the best possible experience with Skate by updating your browser to the latest version.
Compatible Browsers
Generally speaking, Skate supports the stable latest releases of all major web browsers:
- Chrome (version 84+)
- Safari (version 14+)
- Firefox (version 78+)
- Microsoft Edge (version 84+)
Other interfaces using the underlying engines of the aforementioned browsers – that's WebKit, Blink, Gecko – are not explicitly supported but are expected to function correctly.
- Windows 10 - Edge
- Android - Chrome
- MacOS / iOS - Safari
Incompatible Browsers
Skate does not work with:
- Internet Explorer
- Opera
- Developer or Beta versions of supported browsers
Use of Skate on these browsers will potentially lead to bugs and a poor experience with the app. We encourage you to use one of our compatible browsers instead.
Team Conventions
Editing Code
- Create each new feature in its own branch named with the following naming format: initials_description (for example, Jane Smith writing a search function might create a branch called JS_searchfunction)
- Before commiting changes, format Elixir code with
mix format
- Follow Conventional Commit guidelines, by prefacing your commit message with one of the following structural elements:
feat:
(new feature for the user)fix:
(bugfix)chore:
(a housekeeping task; no visible change to user)docs
: (change to documentation)style
: (stylistic change, e.g. formatting of text)test
: (only updates automated tests)
- You can add as many commits as you'd like. If you use the "Squash & Commit" function when deploying to production, you will have the opportunity to consolidate them.
Code Review
All new features are required to be reviewed by a team member. To request a code review after checking in a new branch:
- Create a pull request on your new branch. Edit the description to include a link to the Asana ticket describing the change.
- New pull requests will automatically kick off testing. Wait for the tests to finish (about 10 minutes.)
- Once all the the automated tests pass, request a review from a team member. Update the Asana ticket to "In Review."
Development Deploys
Merge Branch
When a new feature has passed review, you can merge the code to the main branch. Using the "Squash and Merge" button will give you the opportunity to consolidate multiple branch commits with one message.
Delete the branch after merging has completed.
Deploy to Skate-Dev
After merging, using Github Actions or the button in your email, approve and deploy to dev (process takes about 10 minutes.) If the deploy ran successfully, update the Asana ticket to "To be released to prod."
New changes can now be found on Skate dev.
We normally allow a day or two before deploying to prod to ensure everything looks good on dev and to give an opportunity to check for errors in the logfiles.
Optional: Deploy to Skate-Dev-Blue
Use Github Actions to deploy a specific branch to Skate-Dev-Blue to stage changes that are expected to have visible front-facing consequences.
Production Deploys
Prior to releasing a new version to prod, we create an annotated Git tag documenting what's being deployed.
- Find all the git commit logs since the last production update for the body of the description. This will be the output of the following command:
git log --abbrev-commit --pretty=format:'%h:%s' [tag name or hash of previous prod version]..HEAD
To find out the tag name of the most recent production release:
git describe --tags --abbrev=0
Or, to run both commands as one line:
git log --abbrev-commit --pretty=format:'%h:%s' $(git describe --tags --abbrev=0)..HEAD
- The tag name should be in the format
YYYY-MM-DD-N
, whereN
is used to differentiate between multiple releases in a given day and starts at 1. Create the tag with this command:
git tag -a [tag name]
This will prompt you to enter the annotation from the previous step via your editor.
- Once this is done, you can push using:
git push origin --tags
- In Skate's GitHub Releases Page
- Click the "
Draft new release
" button. - Select the tag you just made.
- Click "
Generate release notes
" to auto-generate a description of the release. - Click "
Publish Release
."
- Click the "
- Deploy the created tag to
production
using the "Deploy to Prod (ECS)" GitHub Action. - Mark the Asana Tickets related to the released PR's as completed.
- Find the new changes live at skate.mbta.com