diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index b17a6c5..28d63b9 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -11,7 +11,7 @@ Thank you for helping build open cloud security tooling.
 
 1. Fork and clone the repo
 2. Copy `.env.example` to `.env`
-3. Run `docker compose up -d` for local Postgres
+3. Run `docker compose up -d` for local Postgres and the API. Give Docker at least 6 GiB of RAM so the API image build can finish.
 4. Pick an [open issue](https://github.com/OpenSourceOM/core/issues) or an item from [docs/ROADMAP.md](./docs/ROADMAP.md). For a change that is not tracked yet, open a [discussion](https://github.com/OpenSourceOM/core/discussions) with the `roadmap` label.
 
 ## Pull request reviews
diff --git a/README.md b/README.md
index a8e0e37..77f3d2f 100644
--- a/README.md
+++ b/README.md
@@ -120,6 +120,8 @@ go build -o example-collector ./examples/collector
 open http://localhost:8080
 ```
 
+The API image compiles `github.com/aws/aws-sdk-go-v2/service/ec2`. Give Docker at least 6 GiB of RAM.
+
 `.env.example` sets `OM_API_SECRET=change-me-in-production`, and Compose passes that into the API. In the console, paste that value into the API key field and click **Save API key**. The console then sends it as `X-API-Key` on every `/v1` call except health. Leave the secret empty to keep local API calls open.
 
 **API endpoints:** `GET /v1/health`, `POST /v1/ingest`, `GET /v1/findings`, `GET /v1/graph/snapshot`, `POST /v1/rules/run`, `GET /v1/identity/blast-radius`
diff --git a/docker-compose.yml b/docker-compose.yml
index 36ef57e..33ae81b 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -2,6 +2,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # Local dev stack: Postgres + API
 # Usage: cp .env.example .env && docker compose up -d
+# The API image compiles aws-sdk-go-v2/service/ec2. Docker needs at least 6 GiB of RAM.
 
 services:
   postgres: