feat: add sample for CronJobs

Signed-off-by: Thorsten Hans <[email protected]>

README.md

@@ -10,6 +10,9 @@ If you haven't used Spin before, we highly recommend exploring the [Fermyon Deve
 
 ## Architectures & Patterns in this Repository
 
+### CronJobs in Kubernetes
+- [HTTP APIs and CronJob](./api-with-cronjob)
+
 ### CRUD APIs
 - [Go CRUD API with persistence in SQLite](./http-crud-go-sqlite/)
 - [JavaScript CRUD API with persistence in PostgreSQL](./http-crud-js-pg/)

api-with-cronjob/.gitignore

@@ -0,0 +1,2 @@
+main.wasm
+.spin/

api-with-cronjob/README.md

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+# HTTP API with CronJob
+
+This sample illustrates how you can use the [Spin Command Trigger](https://github.com/fermyon/spin-trigger-command) to one time commands with Spin.
+
+In the context of Kubernetes we can turn one-time commands into Jobs and CronJobs to perform individual tasks once or on a schedule.
+
+The sample consists of two Spin Apps:
+
+* API: A simple HTTP API that interacts with a key-value store
+* CRON: A command app which wipes data from the key-value store
+
+The API exposes the following endpoints
+
+* `GET /value` - Returns the value of a counter from key-value store
+* `POST /value` - Increments the counter in key-value store by `1`
+* `DELETE /value` - Removes the counter from the key-value store
+* `GET /` - Prints available API endpoints
+
+The Command App leverages Spin's key-value store API to load all keys available in the key-value store and deletes them.
+
+## Supported Platforms
+
+- Local (`spin up`)
+- SpinKube
+- Fermyon Platform for Kubernetes
+
+## Prerequisites
+
+To use this sample you must have
+
+- [Rust](https://www.rust-lang.org/) installed on your machine
+  - The `wasm32-wasi` target for Rust installed (`rustup target add wasm32-wasi`)
+- [Spin](https://developer.fermyon.com/spin/v2/index) CLI installed on your machine
+- [Command Trigger Plugin](https://github.com/fermyon/spin-trigger-command) must be installed
+
+
+## Running the Sample
+
+### Local (`spin up`)
+
+Follow the steps outlined below to run the API and the Command App:
+
+- Start the API using `spin up -f spin.toml --runtime-config-file ./local.rtc.toml`
+- Increment the counter by sending `POST` requests to `/value`: `curl -X POST localhost:3000/value`
+- Check the value of the counter using `curl localhost:3000/value` (you should see a value other than `0`)
+- Run the Command App from a clean terminal instance using `spin up -f spin-cron.toml --runtime-config-file ./local.rtc.toml`
+- Check the value of the counter using `curl localhost:3000/value` (it should now return `0`)
+
+### Running on Kubernetes with SpinKube
+
+The [`k8s`](./k8s) folder contains a `deploy.sh` script that you can use to deploy the sample to your Kubernetes cluster.
+
+> You must have [SpinKube](https://spinkube.dev) installed
+
+The script itself deploys the following artifacts to your cluster:
+
+- Redis will be deployed to the `redis` namespace
+- The Runtime Configuration File will be stored in the `rtc` secret in the `default` namespace
+- The API will be deployed to the `default` namespace
+- The Command App will be deployed as a CronJob to the `default` namespace and will be executed every 2nd minute

api-with-cronjob/api/.gitignore

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+target/
+.spin/