Plan

Lono runs a “plan” that provides a preview of what will be deployed by showing the differences.

You are shown what will change. There are 3 plan previews:

  1. Template: This is a diff of the already deployed Template YAML vs the newly built one.
  2. Parameter: This is a diff of the already deployed Parameters vs the new ones.
  3. Changeset: This is a AWS CloudFormation ChangeSet. It provides a high-level overview of what resources will be Modified, Created, and Deleted.

These are all configurable with config/app.rb.

Example

$ lono up demo
Deploying demo-dev stack
...
Template Diff:
=> diff /tmp/lono/diff/template/existing.yml output/demo/template.yml
    4 insertions(+), 9 deletions(-)

Parameter Diff:
Added:
    Parameter1: Value1
Removed:
    Parameter2: Value2
Modified:
    GroupDescription: desc 1 -> desc 2

Change Set Diff:
Calculating Change Set.......
    Modify AWS::EC2::SecurityGroup: SecurityGroup demo-dev-SecurityGroup-10RCAAYLFSKT6
Changes to outputs
Added:
    SecurityGroup
...
Updated demo-dev stack.