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https://github.com/felipecruz91/spinner
Serverless functions built with OpenFaaS to spin new servers on Hetzner Cloud and shut them down automatically when they are unutilized.
https://github.com/felipecruz91/spinner
faasd hetzner hetzner-cloud openfaas serverless
Last synced: 25 days ago
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Serverless functions built with OpenFaaS to spin new servers on Hetzner Cloud and shut them down automatically when they are unutilized.
- Host: GitHub
- URL: https://github.com/felipecruz91/spinner
- Owner: felipecruz91
- License: mit
- Created: 2020-12-28T13:01:33.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2020-12-31T14:34:30.000Z (almost 4 years ago)
- Last Synced: 2023-03-06T04:52:48.396Z (almost 2 years ago)
- Topics: faasd, hetzner, hetzner-cloud, openfaas, serverless
- Language: Go
- Homepage:
- Size: 146 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# spinner ⚡🔄
## Introduction
Serverless functions built with [OpenFaaS](https://www.openfaas.com/) to spin new servers on Hetzner Cloud and shut them down automatically when they are unutilized.
## Use-cases
- Scaling nodes horizontally for video-encoding based on incoming HTTP requests.
## Benefits
- Saving costs for large and expensive servers in Hetzner Cloud provider.
## Prerequisites
- Docker
- [faas-cli](https://github.com/openfaas/faas-cli)
- Terraform
## Provision infrastructure
As of today, the cheapest server type on Hetzner Cloud is `cx11` (1vCPU, 2GB RAM for 3EUR/month). Learn more about the wide range of server types [here](https://www.hetzner.com/cloud).
Let's provision a `cx11` server with `faasd` installed. We'll be using [cloud-init](https://cloudinit.readthedocs.io/en/latest/) to initialize the server with `faasd`, as per the [cloud-config.tpl](cloud-config.tpl) file.
## Overview
To make it easier to provide all prerequisites like the OpenFaaS and Terraform command line utilities, we provide a container image and use it for bootstrapping now.
```cli
docker run --rm -it \
-e TF_VAR_hcloud_token= \
-v ~/.ssh:/root/.ssh \
felipecruz/spinner-infra-boostrap
```
- The `-e TF_VAR_hcloud_token=` env. var is required to authenticate to Hetzner Cloud and provision the infrastructure.
- The `-v ~/.ssh:/root/.ssh` parameter is required to configure the Hetzner server with your SSH key so that you can SSH into it if needed.
Or you could build and run it yourself:
```cli
# Clone the repository
git clone https://github.com/felipecruz91/spinner.git
cd spinner
# Build the bootstrap container
docker build -t spinner-infra-boostrap .
# Exec into the bootstrap container
docker run --rm -it \
-e TF_VAR_hcloud_token= \
-v ~/.ssh:/root/.ssh \
spinner-infra-boostrap
```
## Bootstrap the infrastructure
```cli
# Initialize Terraform
/work # terraform init
# Create the infrastructure in Hetzner Cloud
/work # terraform apply -auto-approve
```
If everything went well, you should see the following output:
```
gateway_url = http://:8080
login_cmd = faas-cli login -g http://:8080 -p
password =
```
Then, access the OpenFaaS UI at http://$FAASD_NODE_IP:8080/ using the username `admin` and the random password generated previously.
As you can see in the picture above, there are two functions already deployed:
- The [spinner](spinner) function serves an endpoint to create a new server to process HTTP requests. It will serve the request by creating a new server of type `cx21` with image `Ubuntu 20.04` located on `nbg1` (Nuremberg) on Hetzner Cloud and will perform a `301 Redirect` to the caller. Replace the `X-Api-Key` value with your own.
```cli
curl -v \
--header "X-Api-Key: " \
http://$FAASD_NODE_IP:8080/function/spinner?server_type=cx21&image_name=ubuntu-20.04&location=nbg1
```
- The [spinner-controller](spinner-controller) function is triggered based on the cron expression defined in [spinner-controller.yml](spinner-controller.yml#L12) and is responsible for deleting any running servers that are not doing any work based on the [provided criteria](spinner-controller.yml#L18-L20).
For instance, if we want to delete any servers whose CPU load is below under 50% in the last 5 minutes, set the following values:
```yaml
metric_name: "cpu"
metric_threshold: "50"
last_minutes: 5
```
and deploy the spinner-controller function again:
```cli
faas-cli login -g http://:8080 -p
faas-cli deploy -g http://:8080 -f spinner-controller.yml
```
Once deployed, it will be automatically called based on the cron schedule.
## Clean up
```cli
# Destroy the infrastructure in Hetzner Cloud
/work # terraform destroy -auto-approve
exit
```
## Troubleshooting
The server should have initialized with the cloud-init configuration right after it has booted. If needed, you could SSH into the server and check the status of the `faasd` service. It should say `active (running)`.
```cli
ssh root@$FAASD_NODE_IP 'systemctl status faasd'
systemctl status faasd
● faasd.service - faasd
Loaded: loaded (/lib/systemd/system/faasd.service; enabled; vendor preset: enabled)
Active: active (running) since Mon 2020-12-28 15:14:15 CET; 12min ago
...
(ommited lines)
...
```
The cloud-init output log file (/var/log/cloud-init-output.log) captures console output so it is easy to debug your scripts following a launch if the instance does not behave the way you intended.
```
ssh root@
cat /var/log/cloud-init-output.log
```