launch-dev-rds-instance-from-snapshot.sh

#!/usr/bin/env bash


cd
set -e


####################
# parameters
####################
# dev-env-db-subnet-group: RDS subnet group of subnets
#   subnet-35760642: subnet for VPC 'vpc-89b6fbec' in 'us-west-2a'
#   subnet-ef7d2f8a: subnet for VPC 'vpc-89b6fbec' in 'us-west-2b'
#   subnet-a9901af0: subnet for VPC 'vpc-89b6fbec' in 'us-west-2c'
db_subnet_group_name="dev-env-db-subnet-group"

# AWS account number not returned by `aws rds describe-db-instances`
aws_account_number="837173812892"

# region not returned by `aws rds describe-db-instances`
db_instance_region="us-west-2"

# db.t2.micro: the cheapest type
db_instance_class="db.t2.micro"

# rds_snapshot
if [ "$1" == "" ]; then
	echo "snapshot ID (e.g. 'rds:instagis2015-2015-09-23-07-23)' is required as first argument"
	exit 1
fi
rds_snapshot=$1

# http://www.howtogeek.com/howto/30184/10-ways-to-generate-a-random-password-from-the-command-line/
rand_hex_value=$(< /dev/urandom tr -dc a-f0-9 | head -c5)
rds_instance_id="ig-dev-$rand_hex_value"

master_username="pgadmin"
# note: password in lowercase
#   http://stackoverflow.com/questions/32762426/what-are-the-limitations-of-postgres-master-password-in-rds
master_user_password=$(< /dev/urandom tr -dc a-z0-9 | head -c32)


####################
# create instance
####################
echo "creating instance from snapshot $rds_snapshot ..."
db_instance_id=$(\
	aws rds restore-db-instance-from-db-snapshot \
	--db-instance-identifier $rds_instance_id --db-snapshot-identifier $rds_snapshot \
	--db-instance-class $db_instance_class --no-multi-az \
	--db-subnet-group-name $db_subnet_group_name \
	--query 'DBInstance.DBInstanceIdentifier' \
	--output text)

echo "db instance id: $db_instance_id"
# e.g. ig-dev-d30b4


echo "waiting for the instance to be available (at least a few minutes) ..."
aws rds wait db-instance-available --db-instance-identifier $db_instance_id
db_instance_arn="arn:aws:rds:$db_instance_region:$aws_account_number:db:$db_instance_id"
# e.g. arn:aws:rds:us-west-2:837173812892:db:ig-dev-7c8d8

db_instance_address=$(
	aws rds describe-db-instances --db-instance-identifier $db_instance_id \
	--query 'DBInstances[*].Endpoint.Address' \
	--output text)

echo "instance arn: $db_instance_arn"
echo "instance endpoint address: $db_instance_address"


####################
# modify instance
####################
echo ""
echo "requesting instance modifications ..."
# note: we may not request modifications when the instance is not available
#   "A client error (InvalidDBInstanceState) occurred when calling the
#   ModifyDBInstance operation: Database instance is not in available state."

echo "db instance values pending to be modified:"
aws rds modify-db-instance --db-instance-identifier $db_instance_id \
--master-user-password $master_user_password \
--backup-retention-period 0 --no-auto-minor-version-upgrade --apply-immediately \
--query 'DBInstance.PendingModifiedValues'

echo "waiting for the modifications to be applied ..."
aws rds wait db-instance-available --db-instance-identifier $db_instance_id
aws rds add-tags-to-resource --resource-name $db_instance_arn --tags Key=env,Value=dev

echo ""
echo "instance master username: $master_username"
echo "instance master user password: $master_user_password"


echo ""
echo "command for connecting to Postgres:"
echo "(you may omit the password and enter it when prompted)"
echo "    psql postgresql://$master_username:$master_user_password@$db_instance_address:5432/pstn_db"