Courier

Courier is a messaging gateway for text-based messaging channels. It abstracts out various different texting mediums and providers, allowing applications to focus on the creation and processing of those messages.

Currently it supports over 50 different channel types, ranging for SMS aggregators like Twilio to IP channels like Facebook and Telegram messenger. The goal is for Courier to support every popular messaging channels and aggregator and we are happy to accept pull requests to help accomplish that.

Courier is currently used to power RapidPro and TextIt but the backend is pluggable, so you can add your own backend to read and write messages.

Deploying

As a Go application, it compiles to a binary and that binary along with the config file is all you need to run it on your server. You can find bundles for each platform in the releases directory. We recommend running it behind a reverse proxy such as nginx or Elastic Load Balancer that provides HTTPs encryption.

Configuration

The service uses a tiered configuration system, each option takes precendence over the ones above it:

1. The configuration file
2. Environment variables starting with COURIER_
3. Command line parameters

We recommend running courier with no changes to the configuration and no parameters, using only environment variables to configure it. You can use % courier --help to see a list of the environment variables and parameters and for more details on each option.

RapidPro

For use with RapidPro, you will want to configure these settings:

• COURIER_DOMAIN: The root domain which courier is exposed as (ex textit.in)
• COURIER_SPOOL_DIR: A local path where courier can spool files if the database is down, should be writable. (ex: /home/courier/spool)
• COURIER_DB: Details parameters used to connect to the Postgres RapidPro database (ex: postgres://textit:fooman@rds.courier.io/5432/textit)
• COURIER_REDIS: Details parameters to use to connect to Redis RapidPro database (ex: redis://redis-internal.courier.io:6379/13)

For writing of message attachments, Courier needs access to an S3 bucket, you can configure access to your bucket via:

• COURIER_S3_REGION: The region for your S3 bucket (ex: ew-west-1)
• COURIER_S3_MEDIA_BUCKET: The name of your S3 bucket (ex: dl-courier)
• COURIER_S3_MEDIA_PREFIX: The prefix to use for filenames of attachments added to your bucket (ex: attachments)
• COURIER_AWS_ACCESS_KEY_ID: The AWS access key id used to authenticate to AWS
• COURIER_AWS_SECRET_ACCESS_KEY The AWS secret access key used to authenticate to AWS

Recommended settings for error and performance monitoring:

• COURIER_LIBRATO_USERNAME: The username to use for logging of events to Librato
• COURIER_LIBRATO_TOKEN: The token to use for logging of events to Librato
• COURIER_SENTRY_DSN: The DSN to use when logging errors to Sentry

Development

Once you've checked out the code, you can build it with:

go install github.com/nyaruka/courier/cmd/courier

This will create a new executable in $GOPATH/bin called courier.

To run the tests you need to create the test database:

$ createdb courier_test
$ createuser -P -E courier
$ psql -d courier_test -f backends/rapidpro/schema.sql
$ psql -d courier_test -c "GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO courier;"
$ psql -d courier_test -c "GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA public TO courier;"

To run all of the tests including benchmarks:

go test ./... -p=1 -bench=.