Techniques of keyless authentication of computing services in distributed computing systems are disclosed herein. One example technique includes upon receiving a command to instantiate a computing service, transmitting a request to an authentication service for an identity assertion token corresponding to an application execution of which instantiates the computing service. The example technique can also include upon receiving the requested identity assertion token, storing the received identity assertion token in the container and modifying an entry of a configuration file in the container that allows the instantiated computing service to access the stored identity assertion token and authenticate to the authentication service using the identity assertion token.