How Do I Review Plans Across All My Units

terragrunt run --all plan streams output from every unit at once, prefixed by unit name. That is useful while it runs and awkward to read afterwards. To get an answer you can review or act on, save the plans instead of scraping the log.

Save a plan file per unit

The --out-dir flag writes a native plan file per unit, in a directory tree that mirrors your stack:

terragrunt run --all --out-dir /tmp/tfplan -- plan

You can then inspect any single unit's plan on its own:

cd app1
terragrunt run -- show /tmp/tfplan/app1/tfplan.tfplan

Applying those exact plans, rather than re-planning, is the same flag:

terragrunt run --all --out-dir /tmp/tfplan -- apply

If you scoped the plan with --filter, pass the same --filter to the apply. Otherwise apply discovers units that have no saved plan and fails.

Get machine-readable plans

For CI checks, gates, or a change summary, add --json-out-dir to also emit show -json output per unit:

terragrunt run --all --out-dir /tmp/tfplan --json-out-dir /tmp/tfjson -- plan

Each unit gets a tfplan.json you can query. For example, to list every resource address with a change that is not a no-op:

jq -r '(.resource_changes // [])[]
       | select(.change.actions != ["no-op"])
       | "\(.change.actions | join(",")) \(.address)"' \
  /tmp/tfjson/app1/tfplan.json

Across every unit at once:

find /tmp/tfjson -name tfplan.json -exec sh -c '
  echo "== $1"
  jq -r "(.resource_changes // [])[]
         | select(.change.actions != [\"no-op\"])
         | \"  \(.change.actions | join(\",\")) \(.address)\"" "$1"
' _ {} \;

Which units ran at all

The run summary prints after every run --all, reporting how many units succeeded, failed, or were excluded. Add --summary-per-unit to see each unit and its duration. For a structured version of the same data, generate a run report as CSV or JSON.

There is no built-in flag that prints a single combined diff for the whole stack. The JSON plans are the supported path to building one.