How to get a refresh token from a service account

Question

Is it possible to get refresh_token from JWT requests that sends to "/oauth2/v4/token" path ?

{
  "access_token" : "1/8xbJqaOZXSUZbHLl5EOtu1pxz3fmmetKx9W8CV4t79M",
  "token_type" : "Bearer",
  "expires_in" : 3600
}

The response doesn't contain refresh token key.

ref link : https://developers.google.com/identity/protocols/OAuth2ServiceAccount

Answer 1

Service accounts dont return refresh tokens. there is no need for a refresh token with a service account. The service account itself can be used to request a new access token whenever you need one.

Oauth2

With normal oauth2 you use a client id and a secret to request permission to access data from the resource owner (user) If the user grants you access you get an access token and possibly a refresh token returned (if you requested offline access). This refresh token is based upon the user and the client that created it. Everytime you use the refresh token it will return an access token giving you access to the user owned by the user who granted you access.

service account

A service account is a user. It has access to some data already set up. anytime you use it to create an access token it would always return the same access. Its not user specific like oauth2 would be.