给定Datomic Cloudformation模板(在这里和这里描述)，我可以在AWS中部署Datomic实例。我也可以使用Terraform来实现自动化。
使用Terraform，我们如何将负载均衡器放在Cloudformation模板中该实例的实例前面？
使用Terraform，我们如何将Route53域名放在Cloudformation模板中的Datomic实例(或负载均衡器)前面？
Datomic Cloudformation模板如下所示：
cf.json
{"Resources":
{"LaunchGroup":
{"Type":"AWS::AutoScaling::AutoScalingGroup",
"Properties":
{"MinSize":{"Ref":"GroupSize"},
"Tags":
[{"Key":"Name",
"Value":{"Ref":"AWS::StackName"},
"PropagateAtLaunch":"true"}],
"MaxSize":{"Ref":"GroupSize"},
"AvailabilityZones":{"Fn::GetAZs":""},
"LaunchConfigurationName":{"Ref":"LaunchConfig"}}},
"LaunchConfig":
{"Type":"AWS::AutoScaling::LaunchConfiguration",
"Properties":
{"ImageId":
{"Fn::FindInMap":
["AWSRegionArch2AMI", {"Ref":"AWS::Region"},
{"Fn::FindInMap":
["AWSInstanceType2Arch", {"Ref":"InstanceType"}, "Arch"]}]},
"UserData":
{"Fn::Base64":
{"Fn::Join":
["n",
["exec > >(tee /var/log/user-data.log|logger -t user-data -s 2>/dev/console) 2>&1",
{"Fn::Join":["=", ["export XMX", {"Ref":"Xmx"}]]},
{"Fn::Join":["=", ["export JAVA_OPTS", {"Ref":"JavaOpts"}]]},
{"Fn::Join":
["=",
["export DATOMIC_DEPLOY_BUCKET",
{"Ref":"DatomicDeployBucket"}]]},
{"Fn::Join":
["=", ["export DATOMIC_VERSION", {"Ref":"DatomicVersion"}]]},
"cd /datomic", "cat <<EOF >aws.properties",
"host=`curl http://169.254.169.254/latest/meta-data/local-ipv4`",
"alt-host=`curl http://169.254.169.254/latest/meta-data/public-ipv4`",
"aws-dynamodb-region=us-east-1naws-transactor-role=datomic-aws-transactor-10naws-peer-role=datomic-aws-peer-10nprotocol=ddbnmemory-index-max=256mnport=4334nmemory-index-threshold=32mnobject-cache-max=128mnlicense-key=naws-dynamodb-table=your-system-name",
"EOF", "chmod 744 aws.properties",
"AWS_ACCESS_KEY_ID="${DATOMIC_READ_DEPLOY_ACCESS_KEY_ID}" AWS_SECRET_ACCESS_KEY="${DATOMIC_READ_DEPLOY_AWS_SECRET_KEY}" aws s3 cp "s3://${DATOMIC_DEPLOY_BUCKET}/${DATOMIC_VERSION}/startup.sh" startup.sh",
"chmod 500 startup.sh", "./startup.sh"]]}},
"InstanceType":{"Ref":"InstanceType"},
"InstanceMonitoring":{"Ref":"InstanceMonitoring"},
"SecurityGroups":{"Ref":"SecurityGroups"},
"IamInstanceProfile":{"Ref":"InstanceProfile"},
"BlockDeviceMappings":
[{"DeviceName":"/dev/sdb", "VirtualName":"ephemeral0"}]}}},
"Mappings":
{"AWSInstanceType2Arch":
{"m3.large":{"Arch":"64h"},
"c4.8xlarge":{"Arch":"64h"},
"t2.2xlarge":{"Arch":"64h"},
"c3.large":{"Arch":"64h"},
"hs1.8xlarge":{"Arch":"64h"},
"i2.xlarge":{"Arch":"64h"},
"r4.4xlarge":{"Arch":"64h"},
"m1.small":{"Arch":"64p"},
"m4.large":{"Arch":"64h"},
"m4.xlarge":{"Arch":"64h"},
"c3.8xlarge":{"Arch":"64h"},
"m1.xlarge":{"Arch":"64p"},
"cr1.8xlarge":{"Arch":"64h"},
"m4.10xlarge":{"Arch":"64h"},
"i3.8xlarge":{"Arch":"64h"},
"m3.2xlarge":{"Arch":"64h"},
"r4.large":{"Arch":"64h"},
"c4.xlarge":{"Arch":"64h"},
"t2.medium":{"Arch":"64h"},
"t2.xlarge":{"Arch":"64h"},
"c4.large":{"Arch":"64h"},
"c3.2xlarge":{"Arch":"64h"},
"m4.2xlarge":{"Arch":"64h"},
"i3.2xlarge":{"Arch":"64h"},
"m2.2xlarge":{"Arch":"64p"},
"c4.2xlarge":{"Arch":"64h"},
"cc2.8xlarge":{"Arch":"64h"},
"hi1.4xlarge":{"Arch":"64p"},
"m4.4xlarge":{"Arch":"64h"},
"i3.16xlarge":{"Arch":"64h"},
"r3.4xlarge":{"Arch":"64h"},
"m1.large":{"Arch":"64p"},
"m2.4xlarge":{"Arch":"64p"},
"c3.4xlarge":{"Arch":"64h"},
"r3.large":{"Arch":"64h"},
"c4.4xlarge":{"Arch":"64h"},
"r3.xlarge":{"Arch":"64h"},
"m2.xlarge":{"Arch":"64p"},
"r4.16xlarge":{"Arch":"64h"},
"t2.large":{"Arch":"64h"},
"m3.xlarge":{"Arch":"64h"},
"i2.4xlarge":{"Arch":"64h"},
"r4.8xlarge":{"Arch":"64h"},
"i3.large":{"Arch":"64h"},
"r3.8xlarge":{"Arch":"64h"},
"c1.medium":{"Arch":"64p"},
"r4.2xlarge":{"Arch":"64h"},
"i2.8xlarge":{"Arch":"64h"},
"m3.medium":{"Arch":"64h"},
"r3.2xlarge":{"Arch":"64h"},
"m1.medium":{"Arch":"64p"},
"i3.4xlarge":{"Arch":"64h"},
"m4.16xlarge":{"Arch":"64h"},
"i3.xlarge":{"Arch":"64h"},
"r4.xlarge":{"Arch":"64h"},
"c1.xlarge":{"Arch":"64p"},
"t1.micro":{"Arch":"64p"},
"c3.xlarge":{"Arch":"64h"},
"i2.2xlarge":{"Arch":"64h"},
"t2.small":{"Arch":"64h"}},
"AWSRegionArch2AMI":
{"ap-northeast-1":{"64p":"ami-eb494d8c", "64h":"ami-81f7cde6"},
"ap-northeast-2":{"64p":"ami-6eb66a00", "64h":"ami-f594489b"},
"ca-central-1":{"64p":"ami-204bf744", "64h":"ami-5e5be73a"},
"us-east-2":{"64p":"ami-5b42643e", "64h":"ami-896c4aec"},
"eu-west-2":{"64p":"ami-e52d3a81", "64h":"ami-55091e31"},
"us-west-1":{"64p":"ami-97cbebf7", "64h":"ami-442a0a24"},
"ap-southeast-1":{"64p":"ami-db1492b8", "64h":"ami-3e90165d"},
"us-west-2":{"64p":"ami-daa5c6ba", "64h":"ami-cb5030ab"},
"eu-central-1":{"64p":"ami-f3f02b9c", "64h":"ami-d564bcba"},
"us-east-1":{"64p":"ami-7f5f1e69", "64h":"ami-da5110cc"},
"eu-west-1":{"64p":"ami-66001700", "64h":"ami-77465211"},
"ap-southeast-2":{"64p":"ami-32cbdf51", "64h":"ami-66647005"},
"ap-south-1":{"64p":"ami-82126eed", "64h":"ami-723c401d"},
"sa-east-1":{"64p":"ami-afd7b9c3", "64h":"ami-ab9af4c7"}}},
"Parameters":
{"InstanceType":
{"Description":"Type of EC2 instance to launch",
"Type":"String",
"Default":"c3.large"},
"InstanceProfile":
{"Description":"Preexisting IAM role / instance profile",
"Type":"String",
"Default":"datomic-aws-transactor-10"},
"Xmx":
{"Description":"Xmx setting for the JVM",
"Type":"String",
"AllowedPattern":"\d+[GgMm]",
"Default":"2625m"},
"GroupSize":
{"Description":"Size of machine group",
"Type":"String",
"Default":"1"},
"InstanceMonitoring":
{"Description":"Detailed monitoring for store instances?",
"Type":"String",
"Default":"true"},
"JavaOpts":
{"Description":"Options passed to Java launcher",
"Type":"String",
"Default":""},
"SecurityGroups":
{"Description":"Preexisting security groups.",
"Type":"CommaDelimitedList",
"Default":"datomic"},
"DatomicDeployBucket":
{"Type":"String",
"Default":"deploy-a0dbc565-faf2-4760-9b7e-29a8e45f428e"},
"DatomicVersion":{"Type":"String", "Default":"0.9.5561.50"}},
"Description":"Datomic Transactor Template"}
samples/cf-template.properties
#################################################################
# AWS instance and group settings
#################################################################
# required
# AWS instance type. See http://aws.amazon.com/ec2/instance-types/ for
# a list of legal instance types.
aws-instance-type=c3.large
# required, see http://docs.amazonwebservices.com/general/latest/gr/rande.html#ddb_region
aws-region=us-east-1
# required
# Enable detailed monitoring of AWS instances.
aws-instance-monitoring=true
# required
# Set group size >1 to create a standby pool for High Availability.
aws-autoscaling-group-size=1
# required, default = 70% of AWS instance RAM
# Passed to java launcher via -Xmx
java-xmx=
#################################################################
# Java VM options
#
# If you set the java-opts property, it will entirely replace the
# value used by bin/transactor, which you should consult as a
# starting point if you are configuring GC.
#
# Note that the single-quoting is necessary due to the whitespace
# between options.
#################################################################
# java-opts='-XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSParallelRemarkEnabled -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly'
#################################################################
# security settings
#
# You must specify at least one of aws-ingress-grops or
# aws-ingress-cidrs to allows peers to connect!
#################################################################
# required
# The transactor needs to run in a security group that opens the
# transactor port to legal peers. If you specify a security group,
# `bin/transactor ensure-cf ...` will ensure that security group
# allows ingress on the transactor port.
aws-security-group=datomic
# Comma-delimited list of security groups. Security group syntax:
# group-name or aws-account-id:group-name
aws-ingress-groups=datomic
# Comma-delimited list of CIDRS.
# aws-ingress-cidrs=0.0.0.0/0
#################################################################
# datomic deployment settings
#################################################################
# required, default = VERSION number of Datomic you deploy from
# Which Datomic version to run.
datomic-version=
# required
# download Datomic from this bucket on startup. You typically will not change this.
datomic-deploy-s3-bucket=some-value
除非你无法轻易避免，否则我不建议将Cloudformation与Terraform混合，因为这会让做很多事情变得很痛苦。通常情况下，我只推荐它用于Cloudformation覆盖资源而不是Terraform的罕见情况。
如果你确实需要这样做，你应该很幸运，因为你的Cloudformation模板向带有实例的自动缩放组添加了一个标记，你可以使用它将负载平衡器链接到自动缩放组，并在创建实例时将实例自身连接到负载平衡器(并在删除实例时分离)。
不幸的是，Cloudformation模板并没有简单地输出自动缩放组名称，因此您可能需要在两个单独的terraform apply操作中执行此操作(可能将配置保存在单独的文件夹中)。
假设你的Cloudformation堆栈是这样的：
resource "aws_cloudformation_stack" "datomic" {
name = "datomic-stack"
...
}
然后一个最小的例子看起来像这样：
data "aws_autoscaling_groups" "datomic" {
filter {
name = "key"
values = ["AWS::StackName"]
}
filter {
name = "value"
values = ["datomic-stack"]
}
}
resource "aws_lb_target_group" "datomic" {
name = "datomic-lb-tg"
port = 80
protocol = "HTTP"
vpc_id = "${var.vpc_id}"
}
resource "aws_lb" "datomic" {
name = "datomic-lb"
internal = false
security_groups = ["${var.security_group_id}"]
subnets = ["${var.subnet_id"]
}
resource "aws_autoscaling_attachment" "asg_attachment" {
autoscaling_group_name = "${data.aws_autoscaling_groups.datomic.names[0]}"
alb_target_group_arn = "${aws_alb_target_group.datomic.arn}"
}
resource "aws_lb_listener" "datomic" {
load_balancer_arn = "${aws_lb.datomic.arn}"
port = "80"
protocol = "HTTP"
default_action {
target_group_arn = "${aws_lb_target_group.datomic.arn}"
type = "forward"
}
}
上面的配置将找到Cloudformation模板创建的自动缩放组，然后将其附加到一个应用程序负载均衡器，该均衡器侦听HTTP流量并将HTTP流量转发到Datomic实例。
从这里开始，将Route53记录添加到负载均衡器是微不足道的，但由于您的实例位于自动缩放组中，您无法轻松为这些实例添加Route53记录(可能不需要)。