Blacklister

This application does the following:

• It responds to the URL like 'http://host/?n=x' and returns n*n.
• It responds to the URL 'http://host/blacklisted' with conditions:
  • return error code 444 to the visitor
  • block the IP of the visitor
  • send an email with IP address to "[email protected]"
  • insert into PostgreSQL table information: path, IP address of the visitor and datetime when he got blocked

Dependencies

• Docker
• Go-migrate
• Golang
• Helm
• Kind
• Kubectl
• Make

You can check dependency versions in .tool-versions file.

Install dependencies

Suggested way to install dependencies is to use 'asdf' tool (except 'docker' and 'make'). If you have the tool installed, run:

# make sure all relevant plugins are installed
cat .tool-versions |\
  while read p; do
    asdf plugin add ${p%% *}
  done

# install dependencies
asdf install

Check docker manual for docker installation instructions: get docker.

Running

IMPORTANT: Make sure you have all dependencies available (see instructions above).

Use the following command to run the application:

make all

This will perform the following actions:

• Start a local Kubernetes cluster using Kind
• Start a local Docker registry
• Build Docker images and push them to local registry
• Deploy Helm chart

Clean-up

You can use this helper to remove Helm release and Kind cluster:

make delete-all

Using application

1. Calculate the square of a number:

curl -XPOST http://localhost:8080/?n=2

2. Blacklist your IP:

curl -XGET http://localhost:8080/blacklisted

3. Get logs:

kubectl logs --context kind-dev -n dev-blacklister -l 'app.kubernetes.io/name=blacklister' -f

Development

You can run the application locally and use the database from the local Kind cluster. To do that you will need to set DB_HOST to localhost and get the DB credentials from secret:

export DB_HOST=localhost
export DB_USER="$(kubectl get secret --context kind-dev -n dev-blacklister "blacklister-blacklister-writer-user.ops-dev-blacklister-db.credentials.postgresql.acid.zalan.do" -o go-template='{{.data.username|base64decode}}')"
export DB_PASSWORD="$(kubectl get secret  --context kind-dev -n dev-blacklister "blacklister-blacklister-writer-user.ops-dev-blacklister-db.credentials.postgresql.acid.zalan.do" -o go-template='{{.data.password|base64decode}}')"

# Run the application
./build/blacklister-darwin-amd64 -log-level debug -dev -listen-address "0.0.0.0:8081"

Here is a list of helpers to aid development process:

• make migrate-up - Run DB migrations
• make migrate-down - Rollback last DB migration
• make migrate-drop - Drop all migrations
• make psql - Login into the database with psql (must have psql installed)
• make build-all - Build code locally
• make test - Run tests
• make docker - Build docker images and push to local registry
• make deploy - Deploy Helm chart
• make help - Display help message

You can also access code reference documentation with: make godoc - this will start a local godoc webserver (see link in the command output).

Versioning

Please maintain application version in VERSION file. Use semantic versioning.