Where does the environment variable is set?

1

Hi all
The https://istio.io/docs/examples/bookinfo/ sample, there are environment variables for example in the productpage.py file:

servicesDomain = "" if (os.environ.get("SERVICES_DOMAIN") is None) else "." + os.environ.get("SERVICES_DOMAIN")

detailsHostname = "details" if (os.environ.get("DETAILS_HOSTNAME") is None) else os.environ.get("DETAILS_HOSTNAME")

ratingsHostname = "ratings" if (os.environ.get("RATINGS_HOSTNAME") is None) else os.environ.get("RATINGS_HOSTNAME")

reviewsHostname = "reviews" if (os.environ.get("REVIEWS_HOSTNAME") is None) else os.environ.get("REVIEWS_HOSTNAME")

I could not figure out, where those variables are set.
Could someone please tell me?

Thanks a lot

2

I would check out the Preparing for Development Wiki guide for Istio below.

3

The Wiki guide does not say much about, how RATINGS_HOSTNAME is setup or environment variables are setup.

What I am trying to achieve is, I would like to create two services, for example Foo and Boo. Foo will call Boo and it has to know the address of Boo. How can I find out the address or how to define it for Boo.

I deployed the app BookInfo on my k8s cluster and it works as expected.

Looking at the review app and how the url of the ratings app is build:

private final static String services_domain = System.getenv("SERVICES_DOMAIN") == null ? "" : ("." + System.getenv("SERVICES_DOMAIN"));
private final static String ratings_hostname = System.getenv("RATINGS_HOSTNAME") == null ? "ratings" : System.getenv("RATINGS_HOSTNAME");
private final static String ratings_service = "http://" + ratings_hostname + services_domain + ":9080/ratings";

Those environment variables have to be set somewhere before the app is deployed.

Thanks

4

Hi, actually they are not set anywhere in the examples. They can be used to change example behavior if You need it.

5

But how the review app knows, which address that rating has? The review app has to know the url of rating app.

6

There in code are default values if env not set

private final static String services_domain = System.getenv("SERVICES_DOMAIN") == null ? "" : ("." + System.getenv("SERVICES_DOMAIN"));
private final static String ratings_hostname = System.getenv("RATINGS_HOSTNAME") == null ? "ratings" : System.getenv("RATINGS_HOSTNAME");
private final static String ratings_service = "http://" + ratings_hostname + services_domain + ":9080/ratings";

actual url if not set will be

http://ratings:9080/ratings

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7

Thanks a lot, I am appreciate a lot.

8

The discussion is helpful, since I did the same thing and had the same confusion.

▶ rg SERVICES_DOMAIN
src/productpage/productpage.py
60:servicesDomain = "" if (os.environ.get("SERVICES_DOMAIN") is None) else "." + os.environ.get("SERVICES_DOMAIN")

src/reviews/reviews-application/src/main/java/application/rest/LibertyRestEndpoint.java
41:    private final static String services_domain = System.getenv("SERVICES_DOMAIN") == null ? "" : ("." + System.getenv("SERVICES_DOMAIN"));

And it’s clear for me now, thanks a lot!

However, I desire to know what’s the best practice to set the env, actually. For example, in deployment yam?

1 Like