AWS Automation

This page describes the functionality of a bash script that automates the setup of SAP Sailing Analytics instances.

Importance

Avoiding misconfiguration of instances due to human mistakes
Allowing fast reaction times to external needs (e.g. horizontal scaling)
Saving time

Scenarios

SAP instance on a dedicated EC2 instance
SAP instance on a shared EC2 instance
SAP instance on a dedicated EC2 instance as a master
SAP instance on a dedicated EC2 instance as a replica

Basics

1. Example setup: SAP instance on a dedicated EC2 instance

Parameters necessary for EC2 instance:

Keypair
Instance type (e.g. t2.medium)
Security group
Image
User Data

Example of content for parameter User Data:

MONGODB_HOST=123.123.123.123
MONGODB_PORT=27017
MONGODB_NAME=wcsantander2017 
SERVER_NAME=wcsantander2017
USE_ENVIRONMENT=live-server
INSTALL_FROM_RELEASE=build-201803302246
SERVER_STARTUP_NOTIFY=leon.radeck@sap.com

2. SAP instance configuration

[image1]

Necessary configuration steps:

Create event in admin console
Create new user account with permissions for that event
Change admin password

If instance home page or event page should be reachable by a specific URL:

Add one of the following lines to /etc/httpd/conf.d/001-events.conf:

Use Home-SSL [instance name].sapsailing.com 127.0.0.1 8888"

Use Event-SSL [instance name].sapsailing.com “[event id]“ 127.0.0.1 8888

Then check and reload apache configuration by entering the commands:

apachectl configtest
sudo service httpd reload

3. Load Balancer configuration

To reach the SAP instance by a specific URL (e.g. wcsantander2017.sapsailing.com), follow these steps:

Create target group with name "S-dedicated-wcsantander2017"
Create rule within HTTPS listener of load balancer. Enter "wcsantander2017.sapsailing.com" as a host name matching rule. Choose target group created in step one.
Configure the health check of the target group
Register instance within the target group

[image2]

AWS Command Line Interface (AWS CLI)

Information about installation and configuration of the AWS CLI can be found here https://aws.amazon.com/de/cli/.

Example command and response of the AWS CLI to get information about all existing EC2 instances of a region:

Command: aws –region eu-west-2 ec2 describe-instances

Response:

{
“Reservations”: [
 {
“Instances”: [
 {
“Monitoring”: {
“State”: “disabled”
 },
“PublicDnsName”: “ec2-35-178-117-16.eu-west-2.compute.amazonaws.com”,
“State”: {
“Code”: 16,
“Name”: “running”
 },
“EbsOptimized”: false,
“LaunchTime”: “2018-04-06T04:09:29.000Z”,
“PublicIpAddress”: “35.178.117.16”,
“PrivateIpAddress”: “172.31.38.162”,
“ProductCodes”: [],
“VpcId”: “vpc-e5ba568c”,
“StateTransitionReason”: “”,
“InstanceId”: “i-066952116fe71fa65”,
“ImageId”: “ami-39f3e25d”,
“PrivateDnsName”: “ip-172-31-38-162.eu-west-2.compute.internal”,
“KeyName”: “leonradeck-keypair”,
[...]

Filtering

Limit instances that are returned by passing a parameter:

aws ec2 describe-instances –instance-ids i-066952116fe71fa65

Querying

Get value of specific attribute:

aws ec2 describe-instances –instance-ids i-066952116fe71fa65 –query ‘Reservations[*].Instances[*]. PublicDnsName’

aws ec2 describe-vpcs –query ‘Vpcs[?IsDefault==true].VpcId’

More syntax information can be found here http://jmespath.org/.

Formatting

Use text as output format:

public_dns_name=$(aws ec2 describe-instances –instance-ids i-066952116fe71fa65 –query ‘Reservations[]. Instances[].PublicDnsName’ –output text)

Script

Files

aws-setup.sh:

Parameter processing
Sourcing of utils.sh, ~/aws-automation/confi g, ~/aws-automation/confi g-[region].sh
Start of scenarios
Helper methods

lib/build-config.sh:

GitHub script to write and read user configuration variables

lib/functions_app.sh:

Functions that relate to SAP instance configuration

lib/functions_ec2.sh:

Functions that relate to EC2 instance configuration

lib/functions_elb.sh:

Functions that relate to Elastic Load Balancing

lib/functions_io.sh:

Input processing (optional input, passwords, value proposals, default initialization)
Creation of user configuration files

lib/functions_wrapper.sh:

Wrapper functions with error handling logic

lib/require_variables.sh:

Declare input variable attributes (optional, required, password, default value, user question)

lib/scenario_associate_alb.sh:

Associate instance with load balancer (target group, health check, rule, apache configuration)

lib/scenario_instance.sh:

Create event
Change admin password
Associate with load balancer (target group, health check, rule, apache configuration)

lib/scenario_master_instance.sh:

Create instance with correct user data to be used as master
Create launch template for replica with matching user data to master

lib/scenario_replica_instance.sh:

Starting of a launch template

lib/scenario_shared_instance.sh:

Creation of a SAP instance on an existing EC2 instance
Check preconditions
Associate SAP instance with load balancer

lib/util_functions.sh:

Helper functions

lib/utils.sh:

Sourcing logic

lib/validation.sh:

Validation functions

lib/variables.sh:

Variables

Preconditions

AWS CLI (configured)
Cygwin with following packages: jq, openssh, wget, curl

User input

Every scenario requires user input for specific variables. For example the setup of a dedicated SAP instance on an EC2 instance requires the following variables:

region
load balancer
instance type (e.g. t2.medium)
security group
image
instance name
instanz short name (e.g. for subdomains)
mongodb host and port
alternative SSH user (default: root)
build version
keypair name
keypair path
event name (optional)
new admin password (optional)

aws-automation