# Settings and Environment Variables

In many cases your application could need some external settings or configurations, for example secret keys, database credentials, credentials for email services, etc.

Most of these settings are variable (can change), like database URLs. And many could be sensitive, like secrets.

For this reason it's common to provide them in environment variables that are read by the application.

/// tip

## Develop and verify

After you make a change, you can run `mvn clean teamcity-configs:generate` to generate and verify the generated TeamCity configuration XMLs.

You also need to run `mvn clean verify` with Java 8 before committing changes.

If you have ktlint errors, you can automatically fix them by running `mvn com.github.gantsign.maven:ktlint-maven-plugin:1.1.1:format`.

digraph {
    grpc -> ca [label="Send CSR gRPC Request"]
    subgraph cluster_istioagent {
        label = "Istio Agent"
        color="orange"
        sds
        SecretManager -> caClient [label="Sign CSR"]
        caClient -> grpc
        grpc -> TokenProvider [dir=none,label="Fetch JWT",color=purple]
        grpc -> cfiles [dir=none,label="Fetch Cert",color=purple]

        sds -> SecretManager [label="Generate certificate"]

    delegate!!.useClientMode = mode
  }

  override fun getUseClientMode(): Boolean {
    return delegate!!.useClientMode
  }

  override fun setNeedClientAuth(need: Boolean) {
    delegate!!.needClientAuth = need
  }

  override fun setWantClientAuth(want: Boolean) {
    delegate!!.wantClientAuth = want
  }

  override fun getNeedClientAuth(): Boolean {
    return delegate!!.needClientAuth

from docs_src.background_tasks.tutorial001 import app

client = TestClient(app)


def test():
    log = Path("log.txt")
    if log.is_file():
        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Notification sent in the background"}
    with open("./log.txt") as f:

indent_style = space
indent_size = 4

# We recommend you to keep these unchanged
end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true

# Markdown files sometimes need trailing whitespaces.
[*.md]
trim_trailing_whitespace = false

[*.{yml,yaml}]
indent_size = 2

[gradle/verification-metadata.xml]
indent_size = 3

    } finally {
      notJar.delete();
    }
  }

  public void testGetClassPathEntry() throws MalformedURLException, URISyntaxException {
    if (isWindows()) {
      return; // TODO: b/136041958 - We need to account for drive letters in the path.
    }
    assertEquals(
        new File("/usr/test/dep.jar").toURI(),
        ClassPath.getClassPathEntry(new File("/home/build/outer.jar"), "file:/usr/test/dep.jar")

def get_query(background_tasks: BackgroundTasks, q: Union[str, None] = None):
    if q:
        message = f"found query: {q}\n"
        background_tasks.add_task(write_log, message)
    return q


@app.post("/send-notification/{email}")
async def send_notification(
    email: str, background_tasks: BackgroundTasks, q: str = Depends(get_query)
):
    message = f"message to {email}\n"
    background_tasks.add_task(write_log, message)

# How To - Recipes

Here you will see different recipes or "how to" guides for **several topics**.

Most of these ideas would be more or less **independent**, and in most cases you should only need to study them if they apply directly to **your project**.

If something seems interesting and useful to your project, go ahead and check it, but otherwise, you might probably just skip them.

/// tip

the BSD-style license found in the LICENSE file. -- Binary Distribution Notes If you have just untarred a binary Go distribution, you need to set the environment variable $GOROOT to the full path of the go directory (the one containing this README). You can omit the variable if you unpack it into /usr/local/go, or if you rebuild from sources by running all.bash (see doc/install.html). You should also add the Go binary directory $GOROOT/bin to your shell's path. For example, if you extracted the tar...