demo: add flask and k3s deployment files

To enable demonstrations of application container builds, and deployment
to k*s clusters, we introduce a simple recipes-demo/ structure with a
sample flask application and deployment yaml.

i.e. ensure that "helloworld-flask-deploy" is installed on your image,
and then:

 % kubectl apply -f /etc/flask-app.yaml
 % kubectl label pods zeddii-pod new-label=yoctorule
 % kubectl expose pod zeddii-pod  --port=9000  --target-port=9000 --type=LoadBalancer --name=my-service

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

recipes-demo/helloworld-flask/helloworld-flask/flask-app

@@ -0,0 +1,21 @@
+#!/usr/bin/python3
+
+# Example flask application for containerization
+#
+# Copyright (C) 2021 Bruce Ashfield <bruce.ashfield@gmail.com>
+# License: MIT (see COPYING.MIT at the root of the repository for terms)
+
+from flask import Flask
+
+app = Flask(__name__)
+
+@app.route('/yocto/', methods=['GET', 'POST'])
+def welcome():
+    return "Hello from Yocto!"
+
+@app.route('/oe/', methods=['GET', 'POST'])
+def welcometooe():
+    return "Hello from OpenEmbedded!"
+
+if __name__ == '__main__':
+    app.run(host='0.0.0.0', port=9000)

recipes-demo/helloworld-flask/helloworld-flask/flask-app-service.yaml

@@ -0,0 +1,32 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: @NAME@
+spec:
+  selector:
+    matchLabels:
+      app: @APPNAME@
+  replicas: 1
+  template:
+    metadata:
+      labels:
+        app: @APPNAME@
+    spec:
+      containers:
+      - name: @CONTAINERNAME@
+        image: @CONTAINERIMAGE@
+        ports:
+          - containerPort: @CONTAINERPORT@
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: yocto-flask-service
+spec:
+  ports:
+  - port: @EXTERNALPORT@
+    targetPort: @CONTAINERPORT@
+    name: http
+  selector:
+    app: @APPNAME@
+

recipes-demo/helloworld-flask/helloworld-flask/flask-app.yaml

@@ -0,0 +1,12 @@
+apiVersion: v1
+kind: Pod
+metadata:
+   name: @NAME@
+spec:
+   containers:
+   - name: @CONTAINERNAME@
+     image: @CONTAINERIMAGE@
+     ports:
+     - containerPort: @CONTAINERPORT@
+
+

recipes-demo/helloworld-flask/helloworld-flask_0.1.bb

@@ -0,0 +1,44 @@
+DESCRIPTION = "Demo flask application"
+HOMEPAGE = "https://yoctoproject.org"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
+
+SRC_URI = "file://flask-app \
+           file://flask-app.yaml \
+           file://flask-app-service.yaml"
+
+DEPLOY_TYPE ?= "pod"
+
+NAME ?= "demo"
+APPNAME ?= "yocto-app"
+CONTAINERNAME ?= "yocto-container"
+CONTAINERIMAGE ?= "zeddii/app-container:latest"
+CONTAINERPORT ?= "9000"
+EXTERNALPORT ?= "10000"
+
+do_install() {
+
+    for tgt in flask-app.yaml flask-app-service.yaml; do
+	sed -i 's%\@NAME\@%${NAME}%g' ${WORKDIR}/$tgt
+	sed -i 's%\@APPNAME\@%${APPNAME}%g' ${WORKDIR}/$tgt
+	sed -i 's%\@CONTAINERNAME\@%${CONTAINERNAME}%g' ${WORKDIR}/$tgt
+	sed -i 's%\@CONTAINERIMAGE\@%${CONTAINERIMAGE}%g' ${WORKDIR}/$tgt
+	sed -i 's%\@CONTAINERPORT\@%${CONTAINERPORT}%g' ${WORKDIR}/$tgt
+	sed -i 's%\@EXTERNALPORT\@%${EXTERNALPORT}%g' ${WORKDIR}/$tgt
+    done
+    
+    install -d ${D}${bindir}/
+    install -m 755 ${WORKDIR}/flask-app ${D}${bindir}/
+
+    install -d ${D}${sysconfdir}/deploy
+    install -m 644 ${WORKDIR}/flask-app.yaml ${D}${sysconfdir}/
+    install -m 644 ${WORKDIR}/flask-app-service.yaml ${D}${sysconfdir}/
+}
+
+RDEPENDS:${PN} += "python3-core python3-flask"
+
+PACKAGES:prepend = "${PN}-deploy "
+FILES:${PN}-deploy = "${sysconfdir}/*"
+
+# this rdepends should be conditional on a debug PACKAGECONFIG
+# RDEPENDS:${PN} += "busybox"

recipes-demo/images/app-container.bb

@@ -0,0 +1,10 @@
+SUMMARY = "Basic Application container image"
+LICENSE = "MIT"
+LIC_FILES_CHKSUM = "file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
+
+include container-base.bb
+
+OCI_IMAGE_ENTRYPOINT = "/usr/bin/flask-app"
+CONTAINER_SHELL = "busybox"
+
+IMAGE_INSTALL:append = "helloworld-flask"