diff --git a/README.md b/README.md
index db7af17..5a7145f 100644
--- a/README.md
+++ b/README.md
@@ -13,7 +13,8 @@ fetched from S3 and Prometheus is started.
 | AWS_ACCESS_KEY_ID          | AWS access key                           |
 | AWS_SECRET_ACCESS_KEY      | AWS secret access key |
 
+# Optional Environment Variables
 
-
-
-
+| Key               | Description                                                                                                                 |
+|-------------------|-----------------------------------------------------------------------------------------------------------------------------|
+| PROMETHEUS_FLAGS  | Pass additional flags to prometheus. [refer to docs](https://prometheus.io/docs/prometheus/latest/command-line/prometheus/) |
diff --git a/entrypoint.sh b/entrypoint.sh
index 6caa21e..8615eb6 100644
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -66,4 +66,5 @@ exec /bin/prometheus \
 --storage.tsdb.min-block-duration=2h \
 --storage.tsdb.max-block-duration=2h \
 --storage.tsdb.retention.time=3d \
---log.level=${LOG_LEVEL}
+--log.level=${LOG_LEVEL} \
+${PROMETHEUS_FLAGS}