appserver
Description
This example leverages private load balancing to enable a small number of pay-as-you-go virtual machines running nginx to serve an application.
The load balancer registers itself into a private dns zone that is created as part of the example.
The web servers simply return their name to show which server responded to a request. The front end of the balancer listens to port 80, and the back end of the balancer delivers all traffic to the nginx web servers.
This example also creates a jump host which can be used to issue a curl request against the private balancer front-end (this is how we validate the behavior in our continuous integration environment at Tuono).
This currently only supports AWS - Azure load balancing support will be added here once it is supported.
Concepts
The following concepts are present in this example:
DNS
HTTP
Linux
Load Balancing
Nginx
Userdata
Variables
Virtual Machine
Venues
This example is regularly tested against:
Release Notes
2.0
Added a private DNS zone, and configured balancer to register a record in it. On AWS this is an A record ALIAS to the balancer for both public and private hosted zones.
1.0
Initial release.
Blueprint
---
variables:
admin_username:
description: >-
The administrative username for SSH access to the linux virtual machines.
Note that the web servers are not publicly accessible however they still
require an administrative user configuration.
type: string
default: adminuser
admin_public_key:
description: >-
The administrative public key for SSH access to the linux virtual machines.
Note that the web servers are not publicly accessible however they still
require an administrative user configuration.
type: string
availability_zones:
description: >-
Indicates how many availability zones to spread the virtual machines across.
type: integer
default: 2
min: 1
app_servers:
description: >-
The number of web servers to create.
type: integer
default: 2
min: 1
location:
region:
my-region:
aws: eu-west-3
azure: northeurope
folder:
tuono-appserver:
region: my-region
networking:
network:
appserver:
dns: testzone
range: 10.0.0.0/16
scope: public
dns:
testzone:
fqdn: ci.eng.tuono.dev
subnet:
appzone-(( count )):
# application servers live here
count: (( availability_zones ))
range: 10.0.10(( count )).0/24
network: appserver
firewall: backend-access
zone: (( count ))
jumpzone:
# jumphost lives here
range: 10.0.1.0/24
network: appserver
firewall: jumpzone-access
scope: public
firewall:
backend-access:
rules:
- services: internal-http-dev
from: networking.network.appserver
to: self
- services: internal-http-dev
from: self
to: networking.network.appserver
jumpzone-access:
rules:
- from: any
to: self
protocols: jumpaccess
protocol:
jumpaccess:
ports:
- port: 22
proto: tcp
service:
dmz-http:
# local traffic (from the jump host)
port: 80
protocol: http
internal-http-dev:
# traffic for the app servers internally
port: 8080
protocol: http
balancer:
appserver-balancer:
network: appserver
scope: private
purpose: testing
routes:
- from: dmz-http
to: internal-http-dev
dns:
# server.ci.eng.tuono.dev
domain: testzone
hostname: server
compute:
image:
bitnami:
publisher: bitnami
product: nginxstack
sku: 1-9
venue:
aws:
image_id: ami-06491c3a2d933c1ca
vm:
appserver:
count: (( app_servers ))
cores: 1
memory: 1 GB
image: bitnami
nics:
default:
ips:
- private:
type: dynamic
firewall: backend-access
provides: internal-http-dev
subnet: appzone-(( 1 + ((count - 1) % availability_zones) ))
# until ch3883 is resolved on azure you also need to specify the zone here
zone: (( 1 + ((count - 1) % availability_zones) ))
configure:
admin:
# required to initiate a deploy on Azure, but ignored on AWS
# when userdata is present
username: (( admin_username ))
public_key: (( admin_public_key ))
userdata:
# why not use cloud-init?
# answer: the azure bitnami nginx marketplace image has disabled cloud-init
# so we have to use a shell script to make a portable example
type: shell
content: |
#!/bin/sh
### debugging mode so we can see what is happening in the logs
set -x
### set up administrative user (idempotent)
userid=$(id -u (( admin_username )))
if [ -z "$userid" ]; then
set -e
adduser --gecos "" --disabled-password (( admin_username ))
cd ~(( admin_username ))
mkdir .ssh
chmod 700 .ssh
echo "(( admin_public_key ))" > .ssh/authorized_keys
chmod 600 .ssh/authorized_keys
chown -R (( admin_username )).(( admin_username )) .ssh
usermod -aG sudo (( admin_username ))
echo "(( admin_username )) ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
set +e
fi
### set up nginx by replacing the home page
echo 'appserver-(( count ))' > /opt/bitnami/nginx/html/index.html
### make it run on port 8080
sed -i 's/listen 80;/listen 8080;/' /opt/bitnami/nginx/conf/nginx.conf
### restart nginx due to the port change
/opt/bitnami/ctlscript.sh restart nginx
jumphost:
# Right now this is really just a SSH target for a curl command to check the balancer
# Eventually we want to use DNS so this becomes a proxy to the private balancer for testing
cores: 1
memory: 1 GB
image: bitnami
nics:
default:
ips:
- private:
type: dynamic
public:
type: dynamic
firewall: jumpzone-access
consumes: networking.service.dmz-http
subnet: jumpzone
configure:
admin:
# required to initiate a deploy on Azure, but ignored on AWS
# when userdata is present
username: (( admin_username ))
public_key: (( admin_public_key ))
userdata:
# why not use cloud-init?
# answer: the azure bitnami nginx marketplace image has disabled cloud-init
# so we have to use a shell script to make a portable example
type: shell
content: |
#!/bin/sh
### debugging mode so we can see what is happening in the logs
set -x
### set up administrative user (idempotent)
userid=$(id -u (( admin_username )))
if [ -z "$userid" ]; then
set -e
adduser --gecos "" --disabled-password (( admin_username ))
cd ~(( admin_username ))
mkdir .ssh
chmod 700 .ssh
echo "(( admin_public_key ))" > .ssh/authorized_keys
chmod 600 .ssh/authorized_keys
chown -R (( admin_username )).(( admin_username )) .ssh
usermod -aG sudo (( admin_username ))
echo "(( admin_username )) ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers
set +e
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