add AGENT.md for creating apps

charts/apps/AGENT.md

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+# Agent Documentation
+
+This document describes how to create a new application chart for the homelab operator.
+
+## Chart Structure
+
+Each application has its own chart located in a directory under `charts/apps`. The chart should contain the following files:
+
+- `Chart.yaml`: The chart metadata.
+- `values.yaml`: The default values for the chart.
+- `templates/`: A directory containing the Kubernetes resource templates.
+
+## Custom Resources
+
+The homelab operator uses several custom resources to manage applications. These resources are defined in the `templates` directory of the chart.
+
+### `PostgresDatabase`
+
+If the application requires a PostgreSQL database, you can create a `PostgresDatabase` resource. The operator will automatically create a database and a secret containing the connection details. The secret will have the same name as the release with a `-pg-connection` postfix.
+
+Example:
+
+```yaml
+# templates/database.yaml
+apiVersion: homelab.mortenolsen.pro/v1
+kind: PostgresDatabase
+metadata:
+  name: "{{ .Release.Name }}"
+spec:
+  environment: "{{ .Values.globals.environment }}"
+```
+
+The secret has the following values:
+
+- `database`: name of the created database
+- `host`: the hostname of the postgres server
+- `port`: the port of the postgres server
+- `url`: combined url in the format `postgresql://{user}:{password}@{host}:{port}/{database}`
+
+### `OidcClient`
+
+If the application requires OIDC authentication, you can create an `OidcClient` resource. The operator will automatically create an OIDC client and a secret containing the client ID and secret. The secret will have the same name as the release with a `-client` postfix.
+
+You need to specify the redirect URIs for the OIDC client. The subdomain is taken from the `values.yaml` file.
+
+Example:
+
+```yaml
+# templates/client.yaml
+apiVersion: homelab.mortenolsen.pro/v1
+kind: OidcClient
+metadata:
+  name: "{{ .Release.Name }}"
+spec:
+  environment: "{{ .Values.globals.environment }}"
+  redirectUris:
+    - path: /user/oauth2/Authentik/callback
+      subdomain: "{{ .Values.subdomain }}"
+      matchingMode: strict
+```
+
+The secret has the following value:
+
+- `authorization`: Authorization endpoint
+- `clientId`
+- `clientSecret`
+- `configuration`: autodiscovery endpoint
+- `configurationIssuer`: issuer url
+- `endSession`: end session endpoint
+- `jwks`: jwks endpoint
+- `token`: token endpoint
+- `userinfo`: user info endpoint
+
+### `HttpService` and `ExternalHttpService`
+
+To expose the application, you can use either an `HttpService` or an `ExternalHttpService` resource.
+
+- `HttpService`: This will expose the application through the Istio gateway. This is for internal access only.
+- `ExternalHttpService`: This will expose the application through a CloudFlare tunnel. This is for external access.
+
+Both resources take a `subdomain` and a `destination` as parameters. The `destination` is the Kubernetes service to route traffic to.
+
+Example of `HttpService`:
+
+```yaml
+# templates/http-service.yaml
+apiVersion: homelab.mortenolsen.pro/v1
+kind: HttpService
+metadata:
+  name: "{{ .Release.Name }}"
+spec:
+  environment: "{{ .Values.globals.environment }}"
+  subdomain: "{{ .Values.subdomain }}"
+  destination:
+    host: "{{ .Release.Name }}.{{ .Release.Namespace }}.svc.cluster.local"
+    port:
+      number: 80
+```
+
+Example of `ExternalHttpService`:
+
+```yaml
+# templates/external-http-service.yaml
+apiVersion: homelab.mortenolsen.pro/v1
+kind: ExternalHttpService
+metadata:
+  name: "{{ .Release.Name }}"
+spec:
+  environment: "{{ .Values.globals.environment }}"
+  subdomain: "{{ .Values.subdomain }}"
+  destination:
+    host: "{{ .Release.Name }}.{{ .Release.Namespace }}.svc.cluster.local"
+    port:
+      number: 80
+```
+
+## `values.yaml`
+
+The `values.yaml` file should contain the following values:
+
+- `globals.environment`: The environment the application is running in (e.g., `prod`, `dev`).
+- `image.repository`: The Docker image repository.
+- `image.tag`: The Docker image tag.
+- `subdomain`: The subdomain for the application.
+
+Example:
+
+```yaml
+# values.yaml
+globals:
+  environment: prod
+image:
+  repository: docker.gitea.com/gitea
+  tag: latest
+subdomain: gitea
+```