build: run the container through dotenvx with the encrypted .env.production

- image installs @dotenvx/dotenvx (pinned) and starts via
  'dotenvx run -f .env.production --strict -- node server.js'
- only DOTENV_PRIVATE_KEY_PRODUCTION is supplied at runtime; without it the
  container exits(1) (MISSING_PRIVATE_KEY) instead of booting with
  undecryptable credentials
- .env.production copied with --chown=node:node (the source mode is 600)
- .dockerignore excludes .env/.env.local/.env.keys so local envs and the
  private keys never enter the build context

.dockerignore

@@ -4,6 +4,10 @@
 openspec
 tools/node_modules
 tools/test
+# never bake local env files or the private keys into the image
+.env
+.env.local
+.env.keys
 Dockerfile
 .dockerignore
 README.md

Dockerfile

@@ -3,19 +3,29 @@
 # on the field laptop (the wizard reaches it at http://127.0.0.1:9000 from the
 # browser, so the container location does not matter).
 #
+# The encrypted .env.production is baked in; the private key is supplied at
+# runtime and never stored in the image:
+#
 #   docker build -t yreka-tools .
-#   docker run -d -p 4173:4173 --name yreka-tools yreka-tools
+#   docker run -d -p 4173:4173 --name yreka-tools \
+#     --env DOTENV_PRIVATE_KEY_PRODUCTION="$(grep -oP '^DOTENV_PRIVATE_KEY_PRODUCTION=\K.*' .env.keys)" \
+#     yreka-tools
 FROM node:22-alpine
 WORKDIR /app
 
+RUN npm install -g @dotenvx/dotenvx@1.51.4
+
 COPY tools/package.json tools/package-lock.json ./
 RUN npm ci --omit=dev && npm cache clean --force
 
 COPY tools/server.js tools/yrka-auth.js tools/permit.js tools/cropper.js ./
 COPY tools/public ./public
+COPY --chown=node:node .env.production ./
 
 USER node
 EXPOSE 4173
 HEALTHCHECK --interval=30s --timeout=5s --start-period=5s \
   CMD wget -qO- http://127.0.0.1:4173/ >/dev/null || exit 1
-CMD ["node", "server.js"]
+# --strict: fail fast when the private key is missing or decryption fails,
+# instead of starting with unusable credentials.
+CMD ["dotenvx", "run", "-f", ".env.production", "--strict", "--", "node", "server.js"]

README.md

@@ -91,11 +91,20 @@ dotenvx run -f .env -- node tools/server.js          # local, from the repo root
 dotenvx set MINIO_SECRET_KEY "<value>" -f .env       # add/rotate a value
 ```
 
-Deploying with Docker: `--env-file` cannot read encrypted values, so either
-decrypt at deploy time (`dotenvx decrypt -f .env.production --stdout` into a
-runtime env file) or pass `DOTENV_PRIVATE_KEY_PRODUCTION` into the container
-and run through `dotenvx` inside the image (ask if you want the Dockerfile
-wired for that).
+The Docker image contains the encrypted `.env.production` and runs through
+`dotenvx`; only the private key is supplied at runtime (never baked in):
+
+```sh
+docker build -t yreka-tools .
+docker run -d -p 4173:4173 --name yreka-tools \
+  --env DOTENV_PRIVATE_KEY_PRODUCTION="$(grep -oP '^DOTENV_PRIVATE_KEY_PRODUCTION=\K.*' .env.keys)" \
+  yreka-tools
+```
+
+`dotenvx run --strict` makes the container exit rather than start with
+undecryptable credentials. Note that `--env` values are visible to
+`docker inspect`; on a shared host prefer an env file with restrictive
+permissions (`--env-file deploy.keys`) or your platform's secret store.
 
 ## Tests