I think that you are ssh connected to the docker host, not the sandbox container when you are running the ambari-server commands.
Please exit out of the shell session and connect again with the 'ssh firstname.lastname@example.org -p2222'. Then, do the 'ambari-server status' and if it does not show running, do the 'ambari-server start'. After that, go back to http://127.0.0.1:8080.
I have almost similar issue. When using 172.17.0.2 I get same error. But when going to 127.0.0.1:8080 it throws a login page and typing the user as admin and password as what I set by calling the ambari-admin-password-reset screen, it keeps throwing the same login page back.
This whole docker host vs sandbox is very confusing. If I use the terminal window that virtual box shows after it finishes booting up the virtual machine, then i cannot run this password reset command. But if I use putty and open a terminal window to login to 127.0.0.1, then I can run the command and also check the ambari server status. Running ifconfig config from putty terminal window shows 172.17.0.2 as the inet addr under eth0
@ Sasitharan Ravindar
It finally worked for me. I had to change the Host port for "ambari" entry in the Virtual box Port forwarding from 8080 to 8081 after reading this articles last suggestion https://community.hortonworks.com/content/supportkb/48805/issues-connecting-to-ambari-in-the-hdp-san... and then in browser went to localhost:8081 and the login page for Ambari loaded. Make sure you set the admin password first by logging into the sandbox using putty and going to host 127.0.0.1 at port 2222
Logging in via the Docker terminal window that you see after you start the virtual machine does not work. That password change script is not found.