Add installation instructions

Signed-off-by: Matias Pan <matipan@hey.com>

Author: matipan

LICENSE

@@ -0,0 +1,54 @@
+# argocd-github-release-generator
+`argocd-github-release-generator` is an [ArgoCD Plugin Generator](https://argo-cd.readthedocs.io/en/stable/operator-manual/applicationset/Generators-Plugin/) for `ApplicationSet`s that generates an ArgoCD application for each Github Release on a given repository.
+
+## Installing
+> [!NOTE]
+> For installing this project we assume that you have a k8s cluster with ArgoCD installed up and running.
+
+This project is composed of 4 components:
+- [Secret](k8s/install.yaml#L1): stores the ArgoCD Token (used to authorize requests coming from ArgoCD) and an optional GITHUB_PAT (used to access private repositories and/or have a bigger rate limit).
+- [ConfigMap](k8s/install.yaml#L13): contains the plugin configuration that ArgoCD reads to know how to communicate and authenticate with it.
+- [Deployment](k8s/install.yaml#L22): deploys the actual plugin that responds to HTTP requests coming from ArgoCD.
+- [Service](k8s/install.yaml#L69): exposes the deployment internally for ArgoCD to reach it.
+
+To install it in your cluster you can run:
+```terminal
+$ ARGOCD_TOKEN="$(echo -n '<strong_password>' | base64)" envsubst < [URL] | k apply -f -
+```
+
+> [!TIP]
+> If you plan to watch private repositories or have a refresh interval lower than 1 per minute then you must specify a GITHUB_PAT.
+> `$ GITHUB_PAT=<YOUR_PAT> ARGOCD_TOKEN="$(echo -n '<strong_password>' | base64)" envsubst < [URL] | k apply -f -`
+
+## Setting up your ApplicationSet
+
+The plugin receives two parameters that you must configure:
+- `repository`: specify the repository that should be used to look for releases.
+- `min_release`: specify the starting point for the releases. This value is useful to control how many applications you generate and remove applications related to old releases.
+
+> [!NOTE]
+> At the moment this project only supports releases that follow `semver` (e.g `v0.1.0`)
+
+With plugin generators you also configure the interval with which ArgoCD polls this plugin. Keep this interval in mind given that each request to the plugin will make a request to Github's API. If you have not configured a GITHUB_PAT then you have a rate limit of 60 requests per hour (one per minute).
+
+An example ApplicationSet that watches the [dagger/dagger](https://github.com/dagger/dagger) repository every minute and creates applications for releases starting at `v0.9.8`:
+```
+apiVersion: argoproj.io/v1alpha1
+kind: ApplicationSet
+metadata:
+  name: <YOUR_APPLICATION_SET_NAME>
+spec:
+  generators:
+    - plugin:
+        configMapRef:
+          # Specify argocd where the configuration of this plugin can be found
+          name: argocd-github-release-generator
+        input:
+          parameters:
+            repository: "dagger/dagger"
+            min_release: v0.9.8
+        requeueAfterSeconds: 60
+
+  template:
+    [Your application configuration]
+```

README.md

@@ -1,3 +1,24 @@
+apiVersion: v1
+kind: Secret
+metadata:
+  name: argocd-github-release-generator
+  namespace: argocd
+  labels:
+    app.kubernetes.io/part-of: argocd
+type: Opaque
+data:
+  plugin.argocd-github-release-generator.token: ${ARGOCD_TOKEN}
+  plugin.argocd-github-release-generator.github_pat: ${GITHUB_PAT}
+---
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: argocd-github-release-generator
+  namespace: argocd
+data:
+  token: "$argocd-github-release-generator:plugin.argocd-github-release-generator.token"
+  baseUrl: "http://argocd-github-release-generator.argocd.svc.cluster.local:8080"
+---
 apiVersion: apps/v1
 kind: Deployment
 metadata:
@@ -33,7 +54,7 @@ spec:
               key: plugin.argocd-github-release-generator.github_pat
               name: argocd-github-release-generator
         image: ghcr.io/matipan/argocd-github-release-generator:test
-        imagePullPolicy: Always
+        imagePullPolicy: IfNotPresent
         name: argocd-github-release-generator
         ports:
         - containerPort: 8080
@@ -44,3 +65,17 @@ spec:
           requests:
             cpu: 150m
             memory: 100Mi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: argocd-github-release-generator
+  namespace: argocd
+spec:
+  type: ClusterIP
+  selector:
+    app: argocd-github-release-generator
+  ports:
+    - port: 8080
+      name: http
+      targetPort: 8080