Weather Function Sample

This is a Serverless Function that fetches the current weather information from the Open Weather Map service via HTTP. Part of the Function's output includes HTTP response headers, and the HTTP response body. This sample is designed to be deployed on OpenFaaS via a Docker image, in conjunction with Docker Swarm.

Initial Setup

If the ~/.konan/cache directory doesn't exist then you will need to compile a basic Linux amd64 program with konan before proceeding.

1. Clone the Kotlin Native Git repository: git clone https://github.com/JetBrains/kotlin-native ~/repos/kotlin-native
2. Change working directory to the sample: cd ~/repos/kotlin-native/samples/weather_function
3. Copy the Konan cache to the sample: mkdir -p function/.konan || cp -R ~/.konan/cache function/.konan
4. Copy the Gradle Wrapper to the sample: cp ../gradle function
5. Copy the gradlew file to the sample: cp ../gradlew function
6. Create the openweathermap_key.txt file in the function directory: touch function/openweathermap_key.txt
7. Append your Open Weather Map API key to function/openweathermap_key.txt

Building Docker Image

It will be assumed that Docker, and OpenFaaS is already installed along with the OpenFaaS CLI. Build the weather Docker image using the fass-cli tool: faas-cli build -f weather.yml

Usage

Make sure that you have completed the Building Docker Image section before proceeding.

1. Start OpenFaaS
2. Deploy the weather image using the faas-cli tool: faas-cli deploy --image weather --name weather
3. Invoke the weather function (including passing through the location argument) by running the following: echo '-l="christchurch,nz"' | faas-cli invoke weather

Note: The program (weather) can print weather information from a JSON file, eg: ./weather -f="current_weather.json". This functionality isn't available in the Serverless Function unless the file is generated in the ~/repos/kotlin-native/samples/weather_function/function directory, the Dockerfile is updated to include the file in the Docker image, and the image is built (refer to the Building Docker Image section) before deploying the image (refer to the Usage section).