polish the readme

Signed-off-by: Josh Dolitsky <[email protected]>

README.md

@@ -1,15 +1,93 @@
 # wolfi-act
-Dynamic GitHub Actions from Wolfi packages
+Dynamic GitHub Actions from [Wolfi](https://wolfi.dev/) packages
+
+Never worry again about installing your favorite tools using upstream "installer"
+actions or whatever is available in GitHub via `apt-get`.
+
+This action builds an emphermeral container image from the latest Wolfi packages
+and runs your command inside of it.
 
 ## Usage
 
-For example, run a grype scan:
+Pass in `packages` with a comma-separated list of packages available in
+Wolfi, along with a `command` you wish to run.
+
+For example, run a grype and trivy scan on an image:
 
 ```yaml
 - uses: jdolitsky/wolfi-act@main
-    with:
-    packages: grype
-    command: grype cgr.dev/chainguard/nginx
+  with:
+    packages: grype,trivy
+    command: |
+      grype cgr.dev/chainguard/nginx
+      trivy image cgr.dev/chainguard/nginx
 ```
 
-TODO: pass in the github env
+Here's a full Github Actions workflow example which does the following (source [here](./.github/workflows/build.yml)):
+
+1. Installs tools: `curl`, `apko`, `cosign`, `crane`, `grype`, `trivy`
+2. Downloads an apko config file using `curl`
+3. Logs into GHCR using `crane`
+4. Publishes a container image using `apko`
+5. Signs the image using `cosign`
+6. Scans the image with `grype` and `trivy`
+7. Tags the image using `crane`
+8. Ensure that the tagged image runs using `docker`
+
+```yaml
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch: {}
+env:
+  IMAGE_REPO: ghcr.io/${{ github.repository }}/wolfi-act-test
+  APKO_CONFIG: https://raw.githubusercontent.com/chainguard-images/images/main/images/maven/configs/openjdk-17.apko.yaml
+  GHCR_USER: ${{ github.repository_owner }}
+  GHCR_PASS: ${{ github.token }}
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      packages: write
+      id-token: write # needed for GitHub OIDC Token
+    steps:
+      - name: Build, sign, inspect an image using wolfi-act
+        uses: jdolitsky/wolfi-act@main
+        with:
+          packages: curl,apko,cosign,crane,grype,trivy
+          command: |
+            set -x
+
+            # Download an apko config file
+            curl -L -o apko.yaml "${APKO_CONFIG}"
+
+            # Login to GHCR
+            crane auth login ghcr.io -u "${GHCR_USER}" -p "${GHCR_PASS}"
+
+            # Publish image using apko
+            apko publish apko.yaml "${IMAGE_REPO}" \
+              --repository-append=https://packages.wolfi.dev/os \
+              --keyring-append=https://packages.wolfi.dev/os/wolfi-signing.rsa.pub \
+              --package-append=wolfi-baselayout \
+              --arch=x86_64,aarch64 \
+              --image-refs=apko.images.txt | tee apko.index.txt
+            index_digest="$(cat apko.index.txt)"
+
+            # Sign image with cosign
+            cosign sign --yes $(cat apko.images.txt)
+
+            # Scan image with grype and trivy
+            grype "${index_digest}"
+            trivy image "${index_digest}"
+
+            # Tag image using crane
+            crane cp "${index_digest}" "${IMAGE_REPO}:latest"
+
+      - name: Make sure the image runs
+        run: |
+          set -x
+          docker run --rm "${IMAGE_REPO}:latest" --version
+
+```