Background
We run Spring Boot Web applications in Dockerized Tomcats, configured using Spring Boot's externalized configuration (https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-external-config.html).
When upgrading from 8.5.14 to 8.5.16 we noticed our configurations was no longer working. After some investigations we came to conclude that this is a problem with the docker image, not the SpringBoot itself. To demonstrate and reproduce the issues I created a small demo application setup, which can be found here:
https://github.com/jlaci/SpringBootTomcatTestEnv
Setup
The demo application tries to resolve the
property, which is provided in to two places, the application.properties file (which is the default) and overridden in the container by an environmental variable. To illustrate this, here is the application.properties and the docker-compose file for both versions:
application.properties
test.variable=This comes from the default application.properties file
docker-compose.yml
8516-tomcat:
image: tomcat:8.5.16
container_name: 8516-tomcat
volumes:
- ./8516webapps:/usr/local/tomcat/webapps/
environment:
- test.variable=This is set on the container as an ENV var
8514-tomcat:
image: tomcat:8.5.14
container_name: 8514-tomcat
volumes:
- ./8514webapps:/usr/local/tomcat/webapps/
environment:
- test.variable=This is set on the container as an ENV var
The application prints out both the Spring Boot resolved value and the raw environmental variable visible by the JVM.
Expected outcome
The application then resolves the property and the expected outcome is for the environmental variable to override the default one. This was the case in 8.5.14 but not in 8.5.16:
Logs from 8.5.14
2017-07-26 13:08:13.600 INFO 1 --- [ost-startStop-1] hu.jlaci.Application : Spring: Test Variable is: This is set on the container as an ENV var
2017-07-26 13:08:13.600 INFO 1 --- [ost-startStop-1] hu.jlaci.Application : Java : Test Variable is: This is set on the container as an ENV var
Logs from 8.5.16
2017-07-26 13:08:13.350 INFO 1 --- [ost-startStop-1] hu.jlaci.Application : Spring: Test Variable is: This comes from the default application.properties file
2017-07-26 13:08:13.350 INFO 1 --- [ost-startStop-1] hu.jlaci.Application : Java : Test Variable is: null
Eliminated causes
Docker / Docker compose
A manually created container also displays the issue:
docker create --name 8516-manual-tomcat -v /Users/jlaci/Temp/SpringBootEnvTest/8516_manual_webapps:/usr/local/tomcat/webapps/ -e test.variable=This_is_set_on_the_container_as_an_ENV_var tomcat:8.5.16
When listing the environment variables for the containers, apparently each container has the required variable:
8.5.14
CATALINA_HOME=/usr/local/tomcat
CA_CERTIFICATES_JAVA_VERSION=20161107~bpo8+1
GPG_KEYS=05AB33110949707C93A279E3D3EFE6B686867BA6 07E48665A34DCAFAE522E5E6266191C37C037D42 47309207D818FFD8DCD3F83F1931D684307A10A5 541FBE7D8F78B25E055DDEE13C370389288584E7 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 713DA88BE50911535FE716F5208B0AB1D63011C7 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23
HOME=/root
HOSTNAME=e35e5d4b67fe
JAVA_DEBIAN_VERSION=8u121-b13-1~bpo8+1
JAVA_HOME=/docker-java-home/jre
JAVA_VERSION=8u121
LANG=C.UTF-8
LD_LIBRARY_PATH=/usr/local/tomcat/native-jni-lib
OPENSSL_VERSION=1.1.0e-1
PATH=/usr/local/tomcat/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
TOMCAT_ASC_URL=https://www.apache.org/dist/tomcat/tomcat-8/v8.5.14/bin/apache-tomcat-8.5.14.tar.gz.asc
TOMCAT_MAJOR=8
TOMCAT_NATIVE_LIBDIR=/usr/local/tomcat/native-jni-lib
TOMCAT_TGZ_URL=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.14/bin/apache-tomcat-8.5.14.tar.gz
TOMCAT_VERSION=8.5.14
no_proxy=*.local, 169.254/16
test.variable=This is set on the container as an ENV var
8.5.16
CATALINA_HOME=/usr/local/tomcat
CA_CERTIFICATES_JAVA_VERSION=20170531+nmu1
GPG_KEYS=05AB33110949707C93A279E3D3EFE6B686867BA6 07E48665A34DCAFAE522E5E6266191C37C037D42 47309207D818FFD8DCD3F83F1931D684307A10A5 541FBE7D8F78B25E055DDEE13C370389288584E7 61B832AC2F1C5A90F0F9B00A1C506407564C17A3 713DA88BE50911535FE716F5208B0AB1D63011C7 79F7026C690BAA50B92CD8B66A3AD3F4F22C4FED 9BA44C2621385CB966EBA586F72C284D731FABEE A27677289986DB50844682F8ACB77FC2E86E29AC A9C5DF4D22E99998D9875A5110C01C5A2F6059E7 DCFD35E0BF8CA7344752DE8B6FB21E8933C60243 F3A04C595DB5B6A5F1ECA43E3B7BBB100D811BBE F7DA48BB64BCB84ECBA7EE6935CD23C10D498E23
HOME=/root
HOSTNAME=d2c60a8e8f13
JAVA_DEBIAN_VERSION=8u131-b11-2
JAVA_HOME=/docker-java-home/jre
JAVA_VERSION=8u131
LANG=C.UTF-8
LD_LIBRARY_PATH=/usr/local/tomcat/native-jni-lib
OPENSSL_VERSION=1.1.0f-3
PATH=/usr/local/tomcat/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
TOMCAT_ASC_URL=https://www.apache.org/dist/tomcat/tomcat-8/v8.5.16/bin/apache-tomcat-8.5.16.tar.gz.asc
TOMCAT_MAJOR=8
TOMCAT_NATIVE_LIBDIR=/usr/local/tomcat/native-jni-lib
TOMCAT_TGZ_URL=https://www.apache.org/dyn/closer.cgi?action=download&filename=tomcat/tomcat-8/v8.5.16/bin/apache-tomcat-8.5.16.tar.gz
TOMCAT_VERSION=8.5.16
no_proxy=*.local, 169.254/16
test.variable=This is set on the container as an ENV var
Tomcat itself
When run natively on the host os with the following command:
env "test.variable=This is set on the container as an ENV var" ./catalina.sh run
both version works fine
Logs from 8.5.14
2017-07-26 13:29:46.429 INFO 2779 --- [ost-startStop-1] hu.jlaci.Application : Spring: Test Variable is: This is set on the container as an ENV var
2017-07-26 13:29:46.429 INFO 2779 --- [ost-startStop-1] hu.jlaci.Application : Java : Test Variable is: This is set on the container as an ENV var
Logs from 8.5.16
2017-07-26 13:30:17.043 INFO 2791 --- [ost-startStop-1] hu.jlaci.Application : Spring: Test Variable is: This is set on the container as an ENV var
2017-07-26 13:30:17.043 INFO 2791 --- [ost-startStop-1] hu.jlaci.Application : Java : Test Variable is: This is set on the container as an ENV var
Spring Boot
The System.getenv(); call doesn't work either and natively the application is fine.
Workaround
If we use the KEY_NAME=value syntax instead of the key.name=value 8.5.16 works fine:
Docker-Compose
8516-tomcat-different-syntax:
image: tomcat:8.5.16
container_name: 8516-tomcat-different-syntax
volumes:
- ./8516webapps:/usr/local/tomcat/webapps/
environment:
- TEST_VARIABLE=This is set on the container as an ENV var with a different syntax
Logs from 8.5.16 with different syntax
2017-07-26 13:08:13.618 INFO 1 --- [ost-startStop-1] hu.jlaci.Application : Spring: Test Variable is: This is set on the container as an ENV var with a different syntax
2017-07-26 13:08:13.618 INFO 1 --- [ost-startStop-1] hu.jlaci.Application : Java : Test Variable is: null
Conclusion
The support for environmental variables with uncapitalized keys seperated by dots has been lost between 8.5.14 and 8.5.16.
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