feat: add Auth0 WIF token script and update Dockerfile (refs #127)

- Create fetch-auth0-token.sh for Auth0 M2M -> GCP WIF token exchange
- Add jq to Dockerfile system dependencies
- Ensure script is executable in container image

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ocr/Dockerfile

@@ -1,8 +1,8 @@
 # Production Dockerfile for MotoVaultPro OCR Service
 # Uses mirrored base images from Gitea Package Registry
 #
-# Primary engine: PaddleOCR PP-OCRv4 (models baked into image)
-# Cloud fallback: Google Vision (optional, requires API key at runtime)
+# Primary engine: Google Vision via Auth0 WIF (monthly-capped)
+# Fallback engine: PaddleOCR PP-OCRv4 (models baked into image)
 
 # Build argument for registry (defaults to Gitea mirrors, falls back to Docker Hub)
 ARG REGISTRY_MIRRORS=git.motovaultpro.com/egullickson/mirrors
@@ -14,7 +14,8 @@ FROM ${REGISTRY_MIRRORS}/python:3.13-slim
 # - libheif1/libheif-dev: HEIF image support (iPhone photos)
 # - libglib2.0-0: GLib shared library (OpenCV dependency)
 # - libmagic1: File type detection
-# - curl: Health check endpoint
+# - curl: Health check endpoint + Auth0 token fetch
+# - jq: JSON parsing for Auth0 token script
 RUN apt-get update && apt-get install -y --no-install-recommends \
     libgomp1 \
     libheif1 \
@@ -22,6 +23,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     libglib2.0-0 \
     libmagic1 \
     curl \
+    jq \
     && rm -rf /var/lib/apt/lists/*
 
 # Python dependencies
@@ -42,5 +44,8 @@ RUN python -c "from paddleocr import PaddleOCR; PaddleOCR(ocr_version='PP-OCRv4'
 
 COPY . .
 
+# Ensure Auth0 WIF token script is executable
+RUN chmod +x /app/scripts/fetch-auth0-token.sh
+
 EXPOSE 8000
 CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000"]

ocr/scripts/fetch-auth0-token.sh

@@ -0,0 +1,75 @@
+#!/bin/sh
+# fetch-auth0-token.sh -- Auth0 M2M token fetcher for Google WIF
+#
+# Called by the Google Auth library when using executable-sourced
+# credentials (see google-wif-config.json).  Reads Auth0 client
+# credentials from Docker secrets and returns the JWT in the format
+# expected by Google's credential helpers.
+#
+# Exit codes:
+#   0 -- success (JSON with token on stdout)
+#   1 -- missing secrets or curl/jq failure
+
+set -e
+
+CLIENT_ID_FILE="/run/secrets/auth0-ocr-client-id"
+CLIENT_SECRET_FILE="/run/secrets/auth0-ocr-client-secret"
+AUTH0_DOMAIN="motovaultpro.auth0.com"
+AUDIENCE="https://iam.googleapis.com/projects/487954699429/locations/global/workloadIdentityPools/motovaultpro-pool/providers/auth0-provider"
+
+# Read credentials from Docker secrets
+if [ ! -f "$CLIENT_ID_FILE" ]; then
+  echo "Error: $CLIENT_ID_FILE not found" >&2
+  exit 1
+fi
+if [ ! -f "$CLIENT_SECRET_FILE" ]; then
+  echo "Error: $CLIENT_SECRET_FILE not found" >&2
+  exit 1
+fi
+
+CLIENT_ID=$(cat "$CLIENT_ID_FILE" | tr -d '[:space:]')
+CLIENT_SECRET=$(cat "$CLIENT_SECRET_FILE" | tr -d '[:space:]')
+
+# Request M2M token from Auth0
+RESPONSE=$(curl -s --fail-with-body \
+  --request POST \
+  --url "https://${AUTH0_DOMAIN}/oauth/token" \
+  --header 'Content-Type: application/json' \
+  --data "{
+    \"client_id\": \"${CLIENT_ID}\",
+    \"client_secret\": \"${CLIENT_SECRET}\",
+    \"audience\": \"${AUDIENCE}\",
+    \"grant_type\": \"client_credentials\"
+  }")
+
+if [ $? -ne 0 ]; then
+  echo "Error: Auth0 token request failed" >&2
+  echo "$RESPONSE" >&2
+  exit 1
+fi
+
+# Extract the access token
+TOKEN=$(echo "$RESPONSE" | jq -r '.access_token')
+
+if [ -z "$TOKEN" ] || [ "$TOKEN" = "null" ]; then
+  echo "Error: No access_token in Auth0 response" >&2
+  echo "$RESPONSE" >&2
+  exit 1
+fi
+
+EXPIRY=$(echo "$RESPONSE" | jq -r '.expires_in')
+
+# Calculate expiration timestamp (seconds since epoch)
+EXPIRATION_TIME=$(($(date +%s) + ${EXPIRY:-3600}))
+
+# Output in Google executable-sourced credential format
+# https://cloud.google.com/iam/docs/workload-identity-federation-with-other-providers#create_a_credential_configuration
+cat <<GCPEOF
+{
+  "version": 1,
+  "success": true,
+  "token_type": "urn:ietf:params:oauth:token-type:jwt",
+  "id_token": "${TOKEN}",
+  "expiration_time": ${EXPIRATION_TIME}
+}
+GCPEOF