Retrieve secret from Kubernetes in Spring

Question

I have created a secret in Kubernetes and mounted it in a volume, so part of the yaml file looks like this:

volumeMounts:
            - name: test-key
              readOnly: true
              mountPath: /opt/key

Then the secret itself contains:

My problem comes when trying to retrieve it using in Spring. How I'm supposed to do it? What I've tried so far is setting in the application.properties --> spring.datasource.private-key=${PRIVATE_KEY} but it's not working. It gives me a placeholder error:

Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'spring.datasource.private-key' in value "${spring.datasource.private-key}"

Any idea what I'm doing wrong?

UPDATE:

This is the way that Im reading the secret in spring, but it still give me the same error related to the placeholder when deploying:

@Value("${spring.datasource.private-key}")
   private String privateKey;

@Bean
    public PrivateKey getPrivateKeyFromEnvironmentVariable() throws IOException, NoSuchAlgorithmException {
        List<String> activeProfiles = Arrays.asList(environment.getActiveProfiles());

        String key;
        if(activeProfiles.contains(LOCAL_ENVIRONMENT_NAME) ) {
            key = resourceUtil.asString(LOCAL_PRIVATE_KEY_RESOURCE_PATH);
        } else if(activeProfiles.contains(TEST_ENVIRONMENT_NAME)) {
            key = generatePrivateKey();
        } else {
            //key = System.getenv(PRIVATE_KEY_ENVIRONMENT_VARIABLE_NAME);
            key = privateKey;
        }

score 0 · Answer 1 · answered Aug 23 '22 at 08:55

0

I have created a secret in Kubernetes and mounted it in a volume.

But the sprint boot expects environment variable for the PRIVATE_KEY. So only binding will not help.

so I will suggest to create secrets


apiVersion: v1
data:
  private_key: YWRtaW4=
kind: Secret
metadata:
  name: mysecret
type: Opaque

Now reference this secret and set as an environment variable so sprintboot can understand.

apiVersion: v1
kind: Pod
metadata:
  name: secret-env-pod
spec:
  containers:
  - name: mycontainer
    image: busybox
    command: ["env"]
    env:
      - name: PRIVATE_KEY
        valueFrom:
          secretKeyRef:
            name: mysecret
            key: private_key

if you run this, there will be an env name PRIVATE_KEY with value admin that is base64 YWRtaW4= in the secret file.

answered Aug 23 '22 at 08:55

Adiii

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Hello Adiii, so how can I change my code to read it from the properties? – DiegoMG Aug 23 '22 at 10:26
you do not really need to manage anything, just `spring.datasource.private-key=${PRIVATE_KEY}` and it will read from env i.e `PRIVATE_KEY` – Adiii Aug 23 '22 at 10:27
so make sure to set `PRIVATE_KEY` in the environment variable – Adiii Aug 23 '22 at 10:27
Ok. And what't the difference between the envFrom and the env in the yaml. How do I read the envFrom, if it's possible. – DiegoMG Aug 23 '22 at 10:35
Env from reading the secret, while the plan env is same as kind of bash export – Adiii Aug 23 '22 at 11:16
There are two manifest, one create secret, and second manifest read the value from the first manifest which create secret having name my secret – Adiii Aug 23 '22 at 11:17
Ok thank you! Still not working. I've updated the question – DiegoMG Aug 23 '22 at 11:54
you need to update deployment, better to post the manifest – Adiii Aug 23 '22 at 12:42
as it already defined in property file so you need get it from property, not from env https://stackoverflow.com/questions/30528255/how-to-access-a-value-defined-in-the-application-properties-file-in-spring-boot – Adiii Aug 23 '22 at 12:43
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/247485/discussion-between-diegomg-and-adiii). – DiegoMG Aug 23 '22 at 14:06

Retrieve secret from Kubernetes in Spring

1 Answers1