ppaskaris-d2l / tf-output

Obtain terraform outputs

tf-output

Fetches terraform outputs and lets you:

• print them to stdout in different formats
• call another command with them exposed in the environment
• export them to your current shell

Getting Started

You need to install this module and then run it's command from somewhere that has a property initialized terraform environment.

Install

npm install -g tf-output

Usage

Assuming you have a module called database.tf with an output called DATABASE_URL in a folder called terraform/database and you have already set up terraform...

Examples

tf-output database

Would print out something like:

DATABASE_URL="http://database.totallysecure.com"

And:

tf-output database -- node src/app.js

Would call node src/app.js with the DATABASE_URL available in the process environment.

You can also

export $(tf-output database)

Which will populate outputs in to your current shell.

Configuration

Module

-m or --module specifies which module to obtain output from. -m alone uses the dir name as the value. So

tf-output api -m

calls terraform output -m api in terraform/api

Output Format

-f or --format allows you to specify an alternate output format, currently json is supported. This flag is ignored if a command is specified.

Backend Initialization

-a or --auto-init allows you to auto-initialize terraform (terraform init) prior to copying outputs.

-g or --auto-init-get will pull down modules mentioned in the root module during auto-initialization.

Advanced Configuration

Plan Check

-c or --check-plan checks if terraform plan has any unapplied changes (and aborts if it does).

Path Template

-p or -path specifies a path template. tf-output looks for modules according to a path template, which by default is terraform/{dir} - so tf-output api database would look for a module in two directories:

• terraform/database
• terraform/api

You can use more complex path templates. Imagine you deploy your app using the following command:

deploy --stage=dev --region=us-east-1

You might organize your terraform definitions in a number of ways and you can customize where tf-output looks to suit your needs.

tf-output database -p {stage}/{region}/terraform/{dir}

This command would fail, because while it knows the module you are trying to load, it doesn't know what stage and region should be.

You can specify them:

tf-output database api -p {stage}/{region}/terraform/{dir} --stage=dev --region=us-east-1

This would cause tf-output to load modules from:

• dev/us-east-1/terraform/api
• dev/us-east-1/terraform/database

If you run a command through tf-output, it will look ahead for substitution values. This works the same:

tf-output database api -p {stage}/{region}/terraform/{dir} -- deploy --stage=dev --region=us-east-1

Except instead of printing the outputs out to stdout, it would exec deploy --stage=dev --region=us-east-1 with environment variables set, and the path template would still be substituted wtih the right stage and region. This saves you havin to repeat region, stage, etc.