Use stdin to provide password

Author: jozala

.buildkite/hooks/pre-command

@@ -94,11 +94,12 @@ if [[ "${USE_PROD_DOCKER_CREDENTIALS:-}" == "true" ]]; then
   fi
 fi
 
+# Authenticate to the Docker Hub public read-only registry
 if which docker > /dev/null 2>&1; then
   DOCKERHUB_REGISTRY_USERNAME="$(vault read -field=username secret/ci/elastic-elasticsearch/docker_hub_public_ro_credentials)"
   DOCKERHUB_REGISTRY_PASSWORD="$(vault read -field=password secret/ci/elastic-elasticsearch/docker_hub_public_ro_credentials)"
 
-  docker login --username "$DOCKERHUB_REGISTRY_USERNAME" --password "$DOCKERHUB_REGISTRY_PASSWORD" docker.io
+  echo "$DOCKERHUB_REGISTRY_PASSWORD" | docker login --username "$DOCKERHUB_REGISTRY_USERNAME" --password-stdin docker.io
 fi
 
 if [[ "$BUILDKITE_AGENT_META_DATA_PROVIDER" != *"k8s"* ]]; then