使用Docker env中的Spring ResourceUtils或DefaultResourceLoader无法获取classpath资源

Question

I am developing a spring-boot web app, and i need to get some classpath resources, so i use the method below:

@Autowired
private Enviroment env;



 String fileLocation = ResourceUtils.getFile(env.getProperty("common.cert-location")).getAbsolutePath();

---

or

String fileLocation = new DefaultResourceLoader().getResource("filename").getFile().getPath();

Both of them run normally in the local enviroment, but when i pack the app and run it in a Docker image, it throw an exception. How can i get the resource? Thanks!

Answer 1

If I understand correctly, you try to load a file from the filesystem. The file location is passed in using an environment variable.

If that is correct, you can add the file you need in your Dockerfile using ADD myresource.file /myresource.file . This puts myresource.file into the root of your container.

Now, if you run your container, you can pass your environment variable common.cert-location using docker run -e common.cert-location=/myresource.file .

One addition: you can add a Spring Boot application property instead of an environment variable. Then set an environment variable with the same name like your property in your container. Spring Boot should pick up the variable by default.

Instead of letting the container know the variable using the -e parameter, you can also use env_file . This allows you to put all your environment variables into a single file and push them into the container.

In combination with Spring Boot application properties, this allows you to override all application properties with environment variables defined in a single file. I think that is a nice, consistent way of configuring Boot apps inside containers.