diff --git a/Dockerfile b/Dockerfile
index ad97eadd7444794bd4e69bac9cd3197a5dd490f8..cf268b4ac7629c13803908eb9e8554c153cee18d 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM centos_gcc
+FROM centos_gcc:7
 
 WORKDIR /root/
 COPY make_all.sh make_all.sh
diff --git a/build.sh b/build.sh
index 78d6b329a17f981ade005ad537d217a0b1dcbb57..2babd25d6f3e7a8968558faffb461edafac3a1eb 100755
--- a/build.sh
+++ b/build.sh
@@ -1,2 +1,2 @@
 #!/bin/bash
-docker build -t netcdf_hdf .
+docker build -t netcdf_hdf:7 .
diff --git a/export.sh b/export.sh
new file mode 100644
index 0000000000000000000000000000000000000000..cac4054d983448e09ca63145b8f93e7cc5895431
--- /dev/null
+++ b/export.sh
@@ -0,0 +1 @@
+docker save netcdf_hdf:7 > netcdf_hdf7.tar