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DEVELOPING.md

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Developing with vpn-check

The layout of this repo more or less follows this layout and the principles in https://peter.bourgon.org/go-for-industrial-programming/

The entry point for the code is at cmd/vpnck.go. Hopefully reading through that should show the general structure.

The core functionality is set up in a SEDA style, with stages implemented with go routines and the events sent down channels.

Essentially AWS is polled for VPN status, which is passed down to a stage that exposes those metrics for Prometheus to collect. They are then passed down to a stage that makes them available to show in the HTML pages rendered by handlers.

Running locally

As the code interacts with AWS API and uses assume role we use hoverfly to replay captured traffic for local use.

Install hoverfly by brew install SpectoLabs/tap/hoverfly

Use the hoverfly_captures/start.sh script to start hoverfly and load the happy path API interaction

Make a note of the HTTP_PROXY setting the script shows at the end

As we're replaying captured traffic we don't need real AWS credentials, but something that looks valid must be present for the code to run. So to run our code we set a fake AWS key and set a fake role to assume and trust any TLS server (to speak with hoverfly)

HTTP_PROXY="http://localhost:8500" \
  AWS_REGION="eu-west-1" \
  AWS_ACCESS_KEY_ID="abcdfrehgewwedsa" \
  AWS_SECRET_ACCESS_KEY="9087kfjxhb92387kjfdh21123113" \
   go run cmd/vpnck.go \
    -interval 10s \
    -debug \
    -insecure

Now hitting http://localhost:8080/ should show a happy VPN.

Running tests

From the root of the project

go test -timeout 300ms -count=1  -v ./...

Other simulations

Simulations of different AWS responses are in the hoverfly_captures directory. See the README

Using skaffold

You can use skaffold to iterate quickly by detecting code changes and deploying to a k8s cluster. Be aware this will push docker images to the ECR repo and have other side effects. If unsure ask for help.

See the README for minimal instructions.