JWT Token Google Cloud Run

Question

I am developing an application with JWT authentication on the google cloud platform. Server side I added authentication via Cloud API Gateway to a cloud run backend. Now I am making a client to generate the JWT token and pass it in the call. To do this I am creating an application that must be deployed on CloudRun and I am following this documentation: https://cloud.google.com/api-gateway/docs/authenticate-service-account#making_an_authenticated_request. My problem is that I don't know how to indicate what it requires as saKeyfile. I tried to put only the name of the file that under src / main / resources / filetest.json but once I try to call the method it tells me file not found. I tried to indicate also the full path. Can anyone help me?

PS I'm using Java

EDIT: here is my code which is the same of documentation

 public void makeCall() {
    String fullPath="src/main/resources/TEST1-id.json";
    String saEmail="[email protected]";
    String audience="auth";
    int expiryLenght=600;
    String token;
    try {
        token=generateJwt(fullPath,saEmail,audience,expiryLenght);
        System.out.println("Token generated: "+token);
        URL url = new URL("apigatewayurl");
        makeJwtRequest(token, url);
        System.out.println("Call performed");
    } catch (IOException e) {
        e.printStackTrace();
    }

}

private static String generateJwt(final String saKeyfile, final String saEmail,
                                  final String audience, final int expiryLength)
        throws FileNotFoundException, IOException {

    Date now = new Date();
    Date expTime = new Date(System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(expiryLength));

    // Build the JWT payload
    JWTCreator.Builder token = JWT.create()
            .withIssuedAt(now)
            // Expires after 'expiraryLength' seconds
            .withExpiresAt(expTime)
            // Must match 'issuer' in the security configuration in your
            // swagger spec (e.g. service account email)
            .withIssuer(saEmail)
            // Must be either your Endpoints service name, or match the value
            // specified as the 'x-google-audience' in the OpenAPI document
            .withAudience(audience)
            // Subject and email should match the service account's email
            .withSubject(saEmail)
            .withClaim("email", saEmail);

    // Sign the JWT with a service account
    FileInputStream stream = new FileInputStream(saKeyfile);
    ServiceAccountCredentials cred = ServiceAccountCredentials.fromStream(stream);
    RSAPrivateKey key = (RSAPrivateKey) cred.getPrivateKey();
    Algorithm algorithm = Algorithm.RSA256(null, key);
    return token.sign(algorithm);
}

i've tried to use full path like in example and using only /TEST1-id.json

and here there is project structure. Is a springboot application which i will deploy in cloud run

Answer 1

The OP fixed the issue on this way

In the end I put the file in the root and copied it in the docker image and recover it as an environment variable in cloud run