Update example app to include a loadbalancer.

experimental/example/Makefile

@@ -1,7 +1,7 @@
 CC=gcc
 CFLAGS=-g -lpthread
 
-all: qotd.marker app.marker client.marker searchapp.marker shout.marker
+all: qotd.marker app.marker client.marker searchapp.marker shout.marker frontend.marker
 
 qotd/qotd: qotd/qotd.o
 	gcc -o $@ $< $(CFLAGS)
@@ -20,6 +20,7 @@ app.marker: app/*
 client.marker: client/*
 searchapp.marker: searchapp/* searchapp/searchapp
 shout.marker: shout/* shout/shout
+frontend.marker: frontend/*
 %.marker:
 	docker build -t tomwilkie/$(<D) $(<D)/
 	touch $@

experimental/example/README.md

@@ -10,9 +10,9 @@ make all
 # "architecture"
 
 ```
-curl -> app --> searchapp -> elasticsearch
-            |
-            --> qotd -> internet
-            |
-            --> redis
+curl -> frontend --> app --> searchapp -> elasticsearch
+         (nginx) |
+                 --> qotd -> internet
+                 |
+                 --> redis
 ```

experimental/example/app/app.py

@@ -57,4 +57,4 @@ def hello():
 if __name__ == "__main__":
   logging.basicConfig(format='%(asctime)s %(levelname)s %(filename)s:%(lineno)d - %(message)s', level=logging.INFO)
   WSGIRequestHandler.protocol_version = "HTTP/1.1"
-  app.run(host="0.0.0.0", port=5000, debug=True)
+  app.run(host="0.0.0.0", port=80, debug=True)

experimental/example/client/client.py

@@ -3,21 +3,28 @@ import random
 import threading
 import time
 import logging
+import socket
 import sys
 
-app = 'http://app:5000/'
+frontend = 'frontend'
 concurrency = 2
 
+def do_request(s):
+  addrs = socket.getaddrinfo(frontend, 80)
+  if len(addrs) <= 0:
+    return
+  addr = random.choice(addrs)
+  s.get("http://%s:%d" % addr[4], timeout=1.0)
+
 def do_requests():
   s = requests.Session()
   while True:
     try:
-      s.get(app, timeout=1.0)
-      logging.info("Did request")
-      time.sleep(1)
+      do_request(s)
     except:
       logging.error("Error doing request", exc_info=sys.exc_info())
-      time.sleep(1)
+
+    time.sleep(1)
     logging.info("Did request")
 
 def main():

experimental/example/frontend/Dockerfile

@@ -0,0 +1,11 @@
+FROM ubuntu
+MAINTAINER Weaveworks Inc <help@weave.works>
+RUN apt-get update && \
+  apt-get install -y nginx && \
+  rm -rf /var/lib/apt/lists/*
+RUN rm /etc/nginx/sites-available/default && \
+  ln -sf /dev/stdout /var/log/nginx/access.log && \
+  ln -sf /dev/stderr /var/log/nginx/error.log
+COPY default.conf /etc/nginx/conf.d/
+EXPOSE 80
+CMD ["nginx", "-g", "daemon off;"]

experimental/example/frontend/default.conf

@@ -0,0 +1,8 @@
+server {
+    listen 80;
+    resolver dns.weave.local:53;
+
+    location / {
+        proxy_pass http://app.weave.local$request_uri;
+    }
+}

experimental/example/run.sh

@@ -2,24 +2,27 @@
 
 set -eux
 
-REPLICAS=${REPLICAS:-1}
+eval $(weave env)
 
 start_container() {
-    IMAGE=$1
-    BASENAME=${2:-$1}
+    IMAGE=$2
+    BASENAME=$3
+    REPLICAS=$1
+    shift 3
     HOSTNAME=$BASENAME.weave.local
 
     for i in $(seq $REPLICAS); do
         if docker inspect $BASENAME$i >/dev/null 2>&1; then
             docker rm -f $BASENAME$i
         fi
-        weave run --with-dns --name=$BASENAME$i --hostname=$HOSTNAME $IMAGE
+        docker run -d --name=$BASENAME$i --hostname=$HOSTNAME $@ $IMAGE
     done
 }
 
-start_container elasticsearch
-start_container tomwilkie/searchapp searchapp
-start_container redis
-start_container tomwilkie/qotd qotd
-start_container tomwilkie/app app
-start_container tomwilkie/client client
+start_container 1 elasticsearch elasticsearch
+start_container 2 tomwilkie/searchapp searchapp
+start_container 1 redis redis
+start_container 1 tomwilkie/qotd qotd
+start_container 2 tomwilkie/app app
+start_container 2 tomwilkie/frontend frontend --add-host=dns.weave.local:$(weave docker-bridge-ip)
+start_container 1 tomwilkie/client client