To add the header you want you can include the following options in your -z
-config replacer.full_list\\(0\\).description=auth1 \
-config replacer.full_list\\(0\\).enabled=true \
-config replacer.full_list\\(0\\).matchtype=REQ_HEADER \
-config replacer.full_list\\(0\\).matchstr=Authorization \
-config replacer.full_list\\(0\\).regex=false \
-config replacer.full_list\\(0\\).replacement=123456789
So your command would look something like
docker run --rm -v $(Agent.ReleaseDirectory)/docker:/zap/wrk/:rw -t ictu/zap2docker-weekly zap-
baseline.py \
-t https://www.example.com/ProductDetails/v1/details?productId=123456 \
-I -x governreport.xml \
-r testreport.html \
--hook=/zap/auth_hook.py \
-z "auth.loginurl=https://www.example.com/ProductDetails/v1/details?productId=123456" \
-config replacer.full_list\\(0\\).description=auth1 \
-config replacer.full_list\\(0\\).enabled=true \
-config replacer.full_list\\(0\\).matchtype=REQ_HEADER \
-config replacer.full_list\\(0\\).matchstr=api-key \
-config replacer.full_list\\(0\\).regex=false \
-config replacer.full_list\\(0\\).replacement=123
With this you will have the header api-key: 123
added to all of your requests.
Reference: https://www.zaproxy.org/blog/2017-06-19-scanning-apis-with-zap/