Insert element in XML document at specific position with xmlstarlet - xmlstarlet

Question

I'm writing a bash script to edit Tomcat's server.xml file. I have it successfully adding a Connector node. To run this example, download and unpack Apache Tomcat 9, go into the conf directory where there is a server.xml file, and run:
xmlstarlet edit -P --inplace \
--subnode "/Server/Service" \
--type elem -n ConnectorNew -v "" \
--insert //ConnectorNew --type attr -n "port" -v "443" \
--insert //ConnectorNew --type attr -n "protocol" -v "org.apache.coyote.http11.Http11NioProtocol" \
--insert //ConnectorNew --type attr -n "keystoreFile" -v "example-key.pem" \
--insert //ConnectorNew --type attr -n "sslProtocol" -v "TLS" \
--insert //ConnectorNew --type attr -n "SSLEnabled" -v "true" \
--subnode "/Server/Service/ConnectorNew" \
--type elem -n "UpgradeProtocolNew" -v "" \
--insert //UpgradeProtocolNew --type attr -n "className" -v "org.apache.coyote.http2.Http2Protocol" \
--rename //ConnectorNew -v Connector \
--rename //UpgradeProtocolNew -v UpgradeProtocol server.xml
which is pretty cool! Upon running that there will now be a TLS Connector on port 443 with the given example key. That would run as usual assuming the key file exists and it's running as root (real server deployments shouldn't run as root but should use jsvc instead).
However that shows up at the very end of the Service element. I would like ideally to put it in the file after the last existing Connector element so the file looks normal. I don't think order of Connector elements has any effect on Tomcat, although I would like it to look like a normal config file that other people would expect, when they go looking for connector elements.
I assume there's some way to do this with xmlstarlet but I couldn't figure it out.
I hope I can avoid using xslt features to do this because I don't want to have to learn and manage another technology to get this script done.
Thank you!

Answer 1

If you have already a Connector defined in you server.xml you can replace --subnode "/Server/Service" by --append /Server/Service/Connector and this will insert your new Connector element right after the first existent Connector.
xmlstarlet edit -P --inplace \
--append /Server/Service/Connector \
--type elem -n ConnectorNew -v "" \
--insert //ConnectorNew --type attr -n "port" -v "443" \
...
If this is the first Connector to insert you would want to do --insert /Server/Service/Engine and your Connector element will be inserted before the Engine element where Connectors usually reside in the default server.xml
xmlstarlet edit -P --inplace \
--insert /Server/Service/Engine \
--type elem -n ConnectorNew -v "" \
--insert //ConnectorNew --type attr -n "port" -v "443" \
...
You may also want to delete all commented xml elements before you start editing the server.xml so that you have a clean and readable file:
xmlstarlet ed -L -d '//comment()' server.xml
and if you do so, you would need to insert a space before the closing "/>", otherwise tomcat will complain that server.xml is corrupt:
sed -i "s/\"\/>/\" \/>/g" server.xml