[Nexthop] Add a Distro Image demo container example

fboss-image/examples/demo_container/README.md

@@ -0,0 +1 @@
+This example shows how to build a docker container to be run on a device inside the Distro Image.

fboss-image/examples/demo_container/build.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+set -e
+
+dnf builddep -y --spec rpmbuild/SPECS/demo_container.spec
+
+rpmdir=$(pwd)/rpmbuild
+mkdir -p ${rpmdir}/{RPMS,SRPMS,BUILD,BUILDROOT}
+
+rpmbuild -bb --define "_topdir ${rpmdir}" ${rpmdir}/SPECS/demo_container.spec
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd -P)"
+mkdir -p ${SCRIPT_DIR}/dist
+cp ${rpmdir}/RPMS/*/*.rpm ${SCRIPT_DIR}/dist

fboss-image/examples/demo_container/rpmbuild/SOURCES/Dockerfile

@@ -0,0 +1,9 @@
+FROM python:alpine
+
+RUN mkdir /output
+
+RUN pip install cowsay
+
+COPY time.py /time.py
+
+CMD ["python", "/time.py"]

fboss-image/examples/demo_container/rpmbuild/SOURCES/demo_container.service

@@ -0,0 +1,15 @@
+# /usr/lib/systemd/system/demo_container.service
+[Unit]
+Description=Demo Container
+After=network.target
+
+[Service]
+Type=simple
+Restart=on-failure
+TimeoutStartSec=180s
+TimeoutStopSec=10s
+ExecStart=/usr/bin/docker run --rm --name demo_container -v /var/clock:/output --net none demo_container
+ExecStop=/usr/bin/docker stop demo_container
+
+[Install]
+WantedBy=multi-user.target

fboss-image/examples/demo_container/rpmbuild/SOURCES/time.py

@@ -0,0 +1,10 @@
+#!/usr/bin/env python3
+import cowsay
+import time
+
+while True:
+    time.sleep(1)
+
+    s = cowsay.get_output_string("trex", "Current time is " + time.ctime()) + "\n"
+    with open("/output/time.txt", "w") as f:
+        f.write(s)

fboss-image/examples/demo_container/rpmbuild/SPECS/demo_container.spec

@@ -0,0 +1,35 @@
+Name: demo_container
+Version: 1.0
+Release: 1
+Summary: Demo Container
+License: GPL
+BuildRequires: podman-docker
+Requires: podman-docker
+
+%description
+Demo building, installing, and running a container on a device inside the Distro Image.
+
+%prep
+cp %{_sourcedir}/Dockerfile .
+cp %{_sourcedir}/time.py .
+
+%build
+docker build . -t demo_container
+rm -f demo_container.tar
+docker save demo_container -o demo_container.tar
+
+%install
+%{__install} -D -m 644 demo_container.tar %{buildroot}/usr/share/demo_container/demo_container.tar
+%{__install} -D -m 644 %{_sourcedir}/demo_container.service %{buildroot}/usr/lib/systemd/system/demo_container.service
+mkdir -p %{buildroot}/var/clock
+
+%files
+%defattr(-,root,root,-)
+/var/clock
+%config(missingok) /usr/share/demo_container/demo_container.tar
+/usr/lib/systemd/system/demo_container.service
+
+%post
+docker load -i /usr/share/demo_container/demo_container.tar
+rm -rf /usr/share/demo_container
+systemctl enable demo_container.service