main.tf

gistfile1.txt

provider "aws" {
  access_key = "ASDF"
  secret_key = "ASDF"

  region = "us-east-1"
}

resource "aws_security_group" "no_modifications_single_ingress" {
  name = "no_modifications_single_ingress"
  description = "this security group causes NO modifications each run"

  vpc_id = "vpc-abc123"

  ingress {
      from_port = 22
      to_port = 22
      protocol = "tcp"
      cidr_blocks = ["10.0.0.1/32","10.0.0.2/32"]
  }

}

resource "aws_security_group" "causes_modifications_multiple_ingress_same_ports" {
  name = "causes_modifications_multiple_ingress_same_ports"
  description = "this security group CAUSES modifications each run"

  vpc_id = "vpc-abc123"

  ingress {
      from_port = 22
      to_port = 22
      protocol = "tcp"
      cidr_blocks = ["10.0.0.1/32"]
  }

  ingress {
      from_port = 22
      to_port = 22
      protocol = "tcp"
      cidr_blocks = ["10.0.0.2/32"]
  }

}

resource "aws_security_group" "no_modifications_multiple_ingress_different_ports" {
  name = "no_modifications_multiple_ingress_different_ports"
  description = "this security group causes NO modifications each run"

  vpc_id = "vpc-abc123"

  ingress {
      from_port = 22
      to_port = 22
      protocol = "tcp"
      cidr_blocks = ["10.0.0.1/32"]
  }

  ingress {
      from_port = 23
      to_port = 23
      protocol = "tcp"
      cidr_blocks = ["10.0.0.2/32"]
  }

}

output

$ terraform version
Terraform v0.5.3

$ terraform apply
aws_security_group.no_modifications_single_ingress: Creating...
  description:                          "" => "this security group causes NO modifications each run"
  egress.#:                             "" => "<computed>"
  ingress.#:                            "" => "1"
  ingress.3090059975.cidr_blocks.#:     "" => "2"
  ingress.3090059975.cidr_blocks.0:     "" => "10.0.0.1/32"
  ingress.3090059975.cidr_blocks.1:     "" => "10.0.0.2/32"
  ingress.3090059975.from_port:         "" => "22"
  ingress.3090059975.protocol:          "" => "tcp"
  ingress.3090059975.security_groups.#: "" => "0"
  ingress.3090059975.self:              "" => "0"
  ingress.3090059975.to_port:           "" => "22"
  name:                                 "" => "no_modifications_single_ingress"
  owner_id:                             "" => "<computed>"
  vpc_id:                               "" => "vpc-ABC123"
aws_security_group.causes_modifications_multiple_ingress_same_ports: Creating...
  description:                          "" => "this security group CAUSES modifications each run"
  egress.#:                             "" => "<computed>"
  ingress.#:                            "" => "2"
  ingress.1829659312.cidr_blocks.#:     "" => "1"
  ingress.1829659312.cidr_blocks.0:     "" => "10.0.0.1/32"
  ingress.1829659312.from_port:         "" => "22"
  ingress.1829659312.protocol:          "" => "tcp"
  ingress.1829659312.security_groups.#: "" => "0"
  ingress.1829659312.self:              "" => "0"
  ingress.1829659312.to_port:           "" => "22"
  ingress.716052576.cidr_blocks.#:      "" => "1"
  ingress.716052576.cidr_blocks.0:      "" => "10.0.0.2/32"
  ingress.716052576.from_port:          "" => "22"
  ingress.716052576.protocol:           "" => "tcp"
  ingress.716052576.security_groups.#:  "" => "0"
  ingress.716052576.self:               "" => "0"
  ingress.716052576.to_port:            "" => "22"
  name:                                 "" => "causes_modifications_multiple_ingress_same_ports"
  owner_id:                             "" => "<computed>"
  vpc_id:                               "" => "vpc-ABC123"
aws_security_group.no_modifications_multiple_ingress_different_ports: Creating...
  description:                          "" => "this security group causes NO modifications each run"
  egress.#:                             "" => "<computed>"
  ingress.#:                            "" => "2"
  ingress.1829659312.cidr_blocks.#:     "" => "1"
  ingress.1829659312.cidr_blocks.0:     "" => "10.0.0.1/32"
  ingress.1829659312.from_port:         "" => "22"
  ingress.1829659312.protocol:          "" => "tcp"
  ingress.1829659312.security_groups.#: "" => "0"
  ingress.1829659312.self:              "" => "0"
  ingress.1829659312.to_port:           "" => "22"
  ingress.3305596422.cidr_blocks.#:     "" => "1"
  ingress.3305596422.cidr_blocks.0:     "" => "10.0.0.2/32"
  ingress.3305596422.from_port:         "" => "23"
  ingress.3305596422.protocol:          "" => "tcp"
  ingress.3305596422.security_groups.#: "" => "0"
  ingress.3305596422.self:              "" => "0"
  ingress.3305596422.to_port:           "" => "23"
  name:                                 "" => "no_modifications_multiple_ingress_different_ports"
  owner_id:                             "" => "<computed>"
  vpc_id:                               "" => "vpc-ABC123"
aws_security_group.no_modifications_multiple_ingress_different_ports: Creation complete
aws_security_group.no_modifications_single_ingress: Creation complete
aws_security_group.causes_modifications_multiple_ingress_same_ports: Creation complete

Apply complete! Resources: 3 added, 0 changed, 0 destroyed.

The state of your infrastructure has been saved to the path
below. This state is required to modify and destroy your
infrastructure, so keep it safe. To inspect the complete state
use the `terraform show` command.

State path: terraform.tfstate
$ terraform apply
aws_security_group.no_modifications_multiple_ingress_different_ports: Refreshing state... (ID: sg-20f11847)
aws_security_group.causes_modifications_multiple_ingress_same_ports: Refreshing state... (ID: sg-2ef11849)
aws_security_group.no_modifications_single_ingress: Refreshing state... (ID: sg-2ff11848)
aws_security_group.causes_modifications_multiple_ingress_same_ports: Modifying...
  ingress.#:                            "1" => "2"
  ingress.1829659312.cidr_blocks.#:     "0" => "1"
  ingress.1829659312.cidr_blocks.0:     "" => "10.0.0.1/32"
  ingress.1829659312.from_port:         "" => "22"
  ingress.1829659312.protocol:          "" => "tcp"
  ingress.1829659312.security_groups.#: "0" => "0"
  ingress.1829659312.self:              "" => "0"
  ingress.1829659312.to_port:           "" => "22"
  ingress.716052576.cidr_blocks.#:      "0" => "1"
  ingress.716052576.cidr_blocks.0:      "" => "10.0.0.2/32"
  ingress.716052576.from_port:          "" => "22"
  ingress.716052576.protocol:           "" => "tcp"
  ingress.716052576.security_groups.#:  "0" => "0"
  ingress.716052576.self:               "" => "0"
  ingress.716052576.to_port:            "" => "22"
aws_security_group.causes_modifications_multiple_ingress_same_ports: Modifications complete

Apply complete! Resources: 0 added, 1 changed, 0 destroyed.

The state of your infrastructure has been saved to the path
below. This state is required to modify and destroy your
infrastructure, so keep it safe. To inspect the complete state
use the `terraform show` command.

State path: terraform.tfstate
$ terraform apply
aws_security_group.no_modifications_single_ingress: Refreshing state... (ID: sg-2ff11848)
aws_security_group.causes_modifications_multiple_ingress_same_ports: Refreshing state... (ID: sg-2ef11849)
aws_security_group.no_modifications_multiple_ingress_different_ports: Refreshing state... (ID: sg-20f11847)
aws_security_group.causes_modifications_multiple_ingress_same_ports: Modifying...
  ingress.#:                            "1" => "2"
  ingress.1829659312.cidr_blocks.#:     "0" => "1"
  ingress.1829659312.cidr_blocks.0:     "" => "10.0.0.1/32"
  ingress.1829659312.from_port:         "" => "22"
  ingress.1829659312.protocol:          "" => "tcp"
  ingress.1829659312.security_groups.#: "0" => "0"
  ingress.1829659312.self:              "" => "0"
  ingress.1829659312.to_port:           "" => "22"
  ingress.716052576.cidr_blocks.#:      "0" => "1"
  ingress.716052576.cidr_blocks.0:      "" => "10.0.0.2/32"
  ingress.716052576.from_port:          "" => "22"
  ingress.716052576.protocol:           "" => "tcp"
  ingress.716052576.security_groups.#:  "0" => "0"
  ingress.716052576.self:               "" => "0"
  ingress.716052576.to_port:            "" => "22"
aws_security_group.causes_modifications_multiple_ingress_same_ports: Modifications complete

Apply complete! Resources: 0 added, 1 changed, 0 destroyed.

The state of your infrastructure has been saved to the path
below. This state is required to modify and destroy your
infrastructure, so keep it safe. To inspect the complete state
use the `terraform show` command.

State path: terraform.tfstate
$