upgrade tini version
diff --git a/Dockerfile b/Dockerfile
index 0eb538d..cd18919 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -25,10 +25,11 @@
# or config file with your custom jenkins Docker image.
RUN mkdir -p /usr/share/jenkins/ref/init.groovy.d
-ENV TINI_SHA 066ad710107dc7ee05d3aa6e4974f01dc98f3888
+ENV TINI_VERSION 0.9.0
+ENV TINI_SHA fa23d1e20732501c3bb8eeeca423c89ac80ed452
# Use tini as subreaper in Docker container to adopt zombie processes
-RUN curl -fsSL https://github.com/krallin/tini/releases/download/v0.5.0/tini-static -o /bin/tini && chmod +x /bin/tini \
+RUN curl -fsSL https://github.com/krallin/tini/releases/download/v${TINI_VERSION}/tini-static -o /bin/tini && chmod +x /bin/tini \
&& echo "$TINI_SHA /bin/tini" | sha1sum -c -
COPY init.groovy /usr/share/jenkins/ref/init.groovy.d/tcp-slave-agent-port.groovy