Replace python script with node script for portal Dockerfile (#18635)

Signed-off-by: AllForNothing <[email protected]>

make/photon/portal/Dockerfile

@@ -6,17 +6,15 @@ WORKDIR /build_dir
 
 ARG npm_registry=https://registry.npmjs.org
 
-RUN apt-get update \
-    && apt-get install -y --no-install-recommends python-yaml
-
 COPY ./api/v2.0/swagger.yaml /build_dir/swagger.yaml
 COPY src/portal /build_dir
 
 ENV NPM_CONFIG_REGISTRY=${npm_registry}
 RUN npm install --unsafe-perm
 RUN npm run generate-build-timestamp
 RUN node --max_old_space_size=2048 'node_modules/@angular/cli/bin/ng' build --configuration production
-RUN python -c 'import sys, yaml, json; y=yaml.load(sys.stdin.read()); print json.dumps(y)' < swagger.yaml > dist/swagger.json
+RUN npm install [email protected] \
+    && node -e "const yaml = require('js-yaml'); const fs = require('fs'); const swagger = yaml.load(fs.readFileSync('swagger.yaml', 'utf8')); fs.writeFileSync('swagger.json', JSON.stringify(swagger));"
 
 COPY ./LICENSE /build_dir/dist