Create and configure subcommands using YAML

[nitrocode]

Problem:

• I want to modify terraform init to add a new flag -upgrade. I can do it by contributing a new atmos env var, atmos flag, and golang code, and tests.
• I want to integrate opa before a terraform apply -auto-approve
• I want to integrate other hooks like checkov and tfsec

Or I can do it in workflows which are a good escape hatch https://github.com/cloudposse/atmos#workflows

Or I can use the deep merging from atmos to create my tfvars, the workspace name it generates, and the terraform backend it generates in json and run raw terraform from outside of atmos using choria-io appbuilder. 😄

Ref:

• choria-io AppBuilder - docs - recent updates!
• ahoy - Last release is 2017 and does not support arguments well

Here's an example using choria-io appbuilder and it has a pretty decent interface

On mac

Install

brew install atmos yq
brew tap choria-io/tap
brew install choria-io/tap/appbuilder

Setup

mkdir -p ~/Library/Application\ Support/appbuilder/
ln -s $(which appbuilder) /usr/local/bin/atmos-sub
vim ~/Library/Application\ Support/appbuilder/atmos-sub-app.yaml

See configuration below

On geodesic

Install

apt update && apt install -y atmos yq
wget https://github.com/choria-io/appbuilder/releases/download/v0.0.9/appbuilder-0.0.9-amd64.deb
dpkg -i appbuilder-0.0.9-amd64.deb
rm appbuilder-0.0.9-amd64.deb

Setup

mkdir -p /etc/appbuilder
ln -s $(which appbuilder) /usr/local/bin/atmos-sub
vim /etc/appbuilder/atmos-sub-app.yaml

See configuration below

Configuration

name: atmos-sub
description: atmos
author: https://github.com/choria-io/appbuilder
type: parent

commands:
  - name: terraform
    description: terraform subcommands
    type: parent
    commands:
    - name: plan
      description: plan
      arguments:
        - name: component
          description: Name of the component
          required: true
      flags:
        - name: stack
          description: Name of the stack
          required: true
          short: s
      type: exec
      script: |
        set -x
        ATMOS_STACK={{ .Flags.stack | escape }}
        ATMOS_COMPONENT={{ .Arguments.component | escape }}
        ATMOS_BASE_COMPONENT=$(atmos describe component $ATMOS_COMPONENT --stack=$ATMOS_STACK | yq .metadata.component)
        # logic to get the correct terraform workspace
        ATMOS_WORKSPACE=$(atmos describe component $ATMOS_COMPONENT --stack $ATMOS_STACK | yq .workspace)
        # TODO: make the `rm -f` command safer by replacing it with a `find` and `-delete` command
        # The following uses &&s so the command will not continue if a former command fails
        atmos terraform generate backend $ATMOS_COMPONENT --stack $ATMOS_STACK \
        && atmos terraform generate varfile $ATMOS_COMPONENT --stack $ATMOS_STACK \
        && rm -f components/terraform/$ATMOS_BASE_COMPONENT/.terraform.lock.hcl \
        && terraform -chdir=components/terraform/$ATMOS_BASE_COMPONENT \
          init -reconfigure -upgrade \
        && terraform -chdir=components/terraform/$ATMOS_BASE_COMPONENT \
          workspace list \
        && terraform -chdir=components/terraform/$ATMOS_BASE_COMPONENT \
          workspace select $ATMOS_WORKSPACE || terraform -chdir=components/terraform/$ATMOS_BASE_COMPONENT workspace new $ATMOS_WORKSPACE \
        && terraform -chdir=components/terraform/$ATMOS_BASE_COMPONENT \
          plan -out=$ATMOS_WORKSPACE.planfile -var-file=$ATMOS_WORKSPACE.terraform.tfvars.json

This command

atmos-sub terraform plan aws-backup-common --stack mgmt-uw2-sandbox

Would run the following

atmos terraform generate backend aws-backup-common --stack mgmt-uw2-sandbox
terraform -chdir=components/terraform/aws-backup init -reconfigure -upgrade
terraform -chdir=components/terraform/aws-backup workspace list
terraform -chdir=components/terraform/aws-backup workspace select mgmt-uw2-sandbox-aws-backup-common || terraform -chdir=components/terraform/aws-backup workspace new mgmt-uw2-sandbox-aws-backup-common
atmos terraform generate backend aws-backup-common --stack mgmt-uw2-sandbox
atmos terraform generate varfile aws-backup-common --stack mgmt-uw2-sandbox
terraform -chdir=components/terraform/aws-backup plan -out=mgmt-uw2-sandbox-aws-backup-common.planfile -var-file=mgmt-uw2-sandbox-aws-backup-common.terraform.tfvars.json

NOTE:

• If working outside of geodesic, then ATMOS_BASE_PATH and the atmos.yaml will have to be set in order to use the custom provider in the remote-state.tf
• One can optionally prefix the command with BUILDER_DRY_RUN=true in order to see a dump of the commands that would be run and it would resolve the flags passed in.

[nitrocode]

This PR cloudposse/atmos#168 should close this feature request but I have not played with the new feature yet.

[nitrocode]

cc: @osterman @mcalhoun