Adding SQL Server 2019 on RHEL 7 example

Author: VanMSFT

linux/preview/examples/mssql-rhel7-sql2019/Dockerfile

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+# SQL Server 2019 on RHEL 7 sample script
+# This is a sample script shared to help create the SQL Server 2019 containers images based on RHEL 7
+# This script can be modified to add other SQL Server components like polybase, Full text search, and others.
+# Base OS layer: latest RHEL 7 latest image
+FROM registry.access.redhat.com/rhel7:latest
+
+## Adding the required repos for installing SQL Server, tools, and other dependent packages. 
+RUN REPOLIST=rhel-7-server-rpms,packages-microsoft-com-mssql-server-2019,packages-microsoft-com-prod && \
+    curl -o /etc/yum.repos.d/mssql-server.repo https://packages.microsoft.com/config/rhel/7/mssql-server-2019.repo && \
+    curl -o /etc/yum.repos.d/msprod.repo https://packages.microsoft.com/config/rhel/7/prod.repo && \
+    ACCEPT_EULA=Y yum -y install --disablerepo "*" --enablerepo ${REPOLIST} --setopt=tsflags=nodocs \
+      mssql-server mssql-tools unixODBC-devel && \
+    yum clean all
+
+## Providing the required access to the mssql server folders
+RUN mkdir -p -m 770 /var/opt/mssql && chown -R mssql. /var/opt/mssql
+
+## Default SQL Server port
+EXPOSE 1433
+
+## Running SQL containers as non-root
+USER mssql
+
+## Start SQL server
+CMD /opt/mssql/bin/sqlservr