As an example:
I am deploying Terraform module in us-east-1 which will build the infrastructure + cloudfront distribution. Now the same module will be deployed in us-west-1 as part of the Disaster Recovery region. Now since cloudfront it is a global service, how I can point in Terraform module which will be deployed in us-west-1 to use the existing cloudfront?
If these are two modules within the same configuration (i.e. both modules are applied with the same terraform apply command), then you simply pass the aws_cloudfront_distribution resource out of the module where it's created as an output, and pass it into the other module as an input parameter. E.g.:
module1/main.tf
resource "aws_cloudfront_distribution" "mydist" {
...
}
output "mydist" {
value = aws_cloudfront_distribution.mydist
}
module2/main.tf
variable "mydist" {}
main.tf
module "mod1" {
...
}
module "mod2" {
...
mydist = mod1.mydist
}
And now you can access the CloudFront distribution resource from within module2 by using var.mydist.
If these are two modules in entirely separate Terraform configurations, you can either:
Use the aws_cloudfront_distribution data source to get the details about a distribution that was created in a separate configuration
output the distribution from the configuration where it's created, then use the terraform_remote_state data source to retrieve the output from the remote state file.
Related
I am trying to get some references from terraform remote state, and have noticed some differences between terraform state resources / data, and using a terraform_remote_state data object.
For example, I have a terraform module that created an AWS managed directory, with no outputs. Within that module, I can see all resources in the state - e.g. terraform state show aws_directory_service_directory.ad gives me details on the directory - the directory ID, DNS server addresses, etc.
$ terraform state list
aws_directory_service_directory.ad
$ terraform state show aws_directory_service_directory.ad
# aws_directory_service_directory.ad:
resource "aws_directory_service_directory" "ad" {
access_url = "REDACTED"
alias = "REDACTED"
dns_ip_addresses = []
.... etc ....
}
If I then create a new module and add a terraform_remote_state data object, i cannot access any properties of the directory - data.terraform_remote_state.ad.outputs is empty. From within this new module, if I only have the remote state data object, and apply (with no resources), and then use terraform console and show data.terraform_remote_state.ad, it looks like:
$ terraform console
> data.terraform_remote_state.ad
{
"backend" = ".."
"config" = { remote_state config shown here }
"outputs" = {}
}
So the resources are in the state, but not accessible directly. Is this expected behaviour? Is there any way to access the resources in the remote state, or would I need to add attributes into outputs and use data.terraform_remote_state.ad.outputs.whatever_attributes?
You can only access outputs. From docs:
terraform_remote_state only exposes output values
You have to modify the parent module of the other setup and add required outputs.
The other way would be to develop your own, fully custom data source to provide info that you need.
Multiple resources (S3, lambda, etc.) in AWS are created by different teams via Terraform scripts;
I’ve developed my Terraform scripts for CloudWatch monitoring, they require AWS ARN as input;
Is it possible to use my monitoring terraform scripts by each team without copying them to their repos?
Yes you can let each team make use of your terraform scripts by creating them as a module. Then the teams can load them into their own scripts using the module configuration section If you do not use git, or you have all terraform in one repository, there are other ways to load a module
This is how we make and use a large number of modules to have a consistent setup across all teams. We have a git repository for each module like (module_cloudwatch_monitoring). There is nothing special about defining a module, you only need to have variables and outputs defined.
When a team wants to use that module, they can use the module syntax like:
module "cloudwatch_monitoring" {
source = "git::http://your-git-repository-url.git?ref=latest"
resource_arn = "${aws_s3_bucket.my_bucket.id}"
}
If the module was in a local path in the same repository, you could do something like:
module "cloudwatch_monitoring" {
source = "../../modules/cloudwatch_monitoring"
resource_arn = "${aws_s3_bucket.my_bucket.id}"
}
Ok, so I have three .tf-files: main.tf where I state azure as provider, resources.tf where all the my resources are claimed, and variables.tf.
I use variables.tf to store keys used by resources.tf.
However, I want to use variables stored in my variable file to fill in the fields in the backend scope like this:
main.tf:
provider "azurerm" {
version = "=1.5.0"
}
terraform {
backend "azurerm" {
storage_account_name = "${var.sa_name}"
container_name = "${var.c_name}"
key = "${var.key}"
access_key = "${var.access_key}"
}
}
Variables stored in variables.tf like this:
variable "sa_name" {
default = "myStorageAccount"
}
variable "c_name" {
default = "tfstate"
}
variable "key" {
default = "codelab.microsoft.tfstate"
}
variable "access_key" {
default = "weoghwoep489ug40gu ... "
}
I got this when running terraform init:
terraform.backend: configuration cannot contain interpolations
The backend configuration is loaded by Terraform extremely early,
before the core of Terraform can be initialized. This is necessary
because the backend dictates the behavior of that core. The core is
what handles interpolation processing. Because of this, interpolations
cannot be used in backend configuration.
If you'd like to parameterize backend configuration, we recommend
using partial configuration with the "-backend-config" flag to
"terraform init".
Is there a way of solving this? I really want all my keys/secrets in the same file... and not one key in the main which I preferably want to push to git.
Terraform doesn't care much about filenames: it just loads all .tf files in the current directory and processes them. Names like main.tf, variables.tf, and outputs.tf are useful conventions to make it easier for developers to navigate the code, but they won't have much impact on Terraform's behavior.
The reason you're seeing the error is that you're trying to use variables in a backend configuration. Unfortunately, Terraform does not allow any interpolation (any ${...}) in backends. Quoting from the documentation:
Only one backend may be specified and the configuration may not contain interpolations. Terraform will validate this.
So, you have to either hard-code all the values in your backend, or provide a partial configuration and fill in the rest of the configuration via CLI params using an outside tool (e.g., Terragrunt).
There are some important limitations on backend configuration:
A configuration can only provide one backend block.
A backend block cannot refer to named values (like input variables, locals, or data source attributes).
Terraform backends configurations one can see at below link:
https://www.terraform.io/docs/configuration/backend.html
I have 2 repos for my project. A Static website and server. I want the website to be hosted by cloudfront and s3 and the server on elasticbeanstalk. I know these resources will need to know about a route53 resource at least to be under the same domain name for cors to work. Among other things such as vpcs and stuff.
So my question is how do I manage terraform with multiple repos.
I'm thinking I could have a seperate infrastructure repo that builds for all repos.
I could also have them seperate and pass in the arns/names/ids as variables (annoying).
You can use terraform remote_state for this. It lets you read the output variables from another terraform state file.
Lets assume you save your state files remotely on s3 and you have your website.tfstate and server.tfstate file. You could output your hosted zone ID of your route53 zone as hosted_zone_id in your website.tfstate and then reference that output variable directly in your server state terraform code.
data "terraform_remote_state" "website" {
backend = "s3"
config {
bucket = "<website_state_bucket>"
region = "<website_bucket_region>"
key = "website.tfstate"
}
}
resource "aws_route53_record" "www" {
zone_id = "${data.terraform_remote_state.website.hosted_zone_id}"
name = "www.example.com"
type = "A"
ttl = "300"
records = ["${aws_eip.lb.public_ip}"]
}
Note, that you can only read output variables from remote states. You cannot access resources directly, as terraform treats other states/modules as black boxes.
Update
As mentioned in the comments, terraform_remote_state is a simple way to share explicitly published variables across multiple states. However, it comes with 2 issues:
Close coupling between code components, i.e., producer of the variable cannot change easily.
It can only be used by terraform, i.e., you cannot easily share those variables across different layers. Configuration tools such as Ansible cannot use .tfstate natively without some additional custom plugin/wrapper.
The recommended HashiCorp way is to use a central config store such as Consul. It comes with more benefits:
Consumer is decoupled from the variable producer.
Explicit publishing of variables (like in terraform_remote_state).
Can be used by other tools.
A more detailed explanation can be found here.
An approach I've used in the past is to have a single repo for all of the Infrastructure.
An alternative is to have 2 separate tf configurations, each using remote state. Config 1 can use output variables to store any arns/ids as necessary.
Config 2 can then have a remote_state data source to query for the relevant arns/ids.
E.g.
# Declare remote state
data "terraform_remote_state" "network" {
backend = "s3"
config {
bucket = "my-terraform-state"
key = "network/terraform.tfstate"
region = "us-east-1"
}
}
You can then use output values using standard interpolation syntax
${data.terraform_remote_state.network.some_id}
How can I get Terraform 0.10.1 to support two different providers without having to run 'terraform init' every time for each provider?
I am trying to use Terraform to
1) Provision an API server with the 'DigitalOcean' provider
2) Subsequently use the 'Docker' provider to spin up my containers
Any suggestions? Do I need to write an orchestrating script that wraps Terraform?
Terraform's current design struggles with creating "multi-layer" architectures in a single configuration, due to the need to pass dynamic settings from one provider to another:
resource "digitalocean_droplet" "example" {
# (settings for a machine running docker)
}
provider "docker" {
host = "tcp://${digitalocean_droplet.example.ipv4_address_private}:2376/"
}
As you saw in the documentation, passing dynamic values into provider configuration doesn't fully work. It does actually partially work if you use it with care, so one way to get this done is to use a config like the above and then solve the "chicken-and-egg" problem by forcing Terraform to create the droplet first:
$ terraform plan -out=tfplan -target=digitalocean_droplet.example
The above will create a plan that only deals with the droplet and any of its dependencies, ignoring the docker resources. Once the Docker droplet is up and running, you can then re-run Terraform as normal to complete the setup, which should then work as expected because the Droplet's ipv4_address_private attribute will then be known. As long as the droplet is never replaced, Terraform can be used as normal after this.
Using -target is fiddly, and so the current recommendation is to split such systems up into multiple configurations, with one for each conceptual "layer". This does, however, require initializing two separate working directories, which you indicated in your question that you didn't want to do. This -target trick allows you to get it done within a single configuration, at the expense of an unconventional workflow to get it initially bootstrapped.
Maybe you can use a provider instance within your resources/module to set up various resources with various providers.
https://www.terraform.io/docs/configuration/providers.html#multiple-provider-instances
The doc talks about multiple instances of same provider but I believe the same should be doable with distinct providers as well.
A little bit late...
Well, got the same Problem. My workaround is to create modules.
First you need a module for your docker Provider with an ip variable:
# File: ./docker/main.tf
variable "ip" {}
provider "docker" {
host = "tcp://${var.ip}:2375/"
}
resource "docker_container" "www" {
provider = "docker"
name = "www"
}
Next one is to load that modul in your root configuration:
# File: .main.tf
module "docker01" {
source = "./docker"
ip = "192.169.10.12"
}
module "docker02" {
source = "./docker"
ip = "192.169.10.12"
}
True, you will create on every node the same container, but in my case that's what i wanted. I currently haven't found a way to configure the hosts with an individual configuration. Maybe nested modules, but that didn't work in the first tries.