Docker : Error : Unable to communicate with master!

I am following the simple Docker tutorial and coming across “ERROR: Unable to communicate with master!”. Here’s the output :

dparkar@dupin:~ docker pull ros Using default tag: latest latest: Pulling from library/ros 6b98dfc16071: Pull complete 4001a1209541: Pull complete 6319fc68c576: Pull complete b24603670dc3: Pull complete 97f170c87c6f: Pull complete 979f74553e2f: Pull complete 2413da49cb9d: Pull complete 652985201ab5: Pull complete e828be34f7aa: Pull complete 308b41b91982: Pull complete f2de7c187505: Pull complete 76d678fbdf1b: Pull complete 8a4ec92e7e79: Pull complete 25e2b1ab5d6f: Pull complete Digest: sha256:842160e6c266f3853b190d7f10e223fcaf4f1ead1852976aa529082d0b0bbcb6 Status: Downloaded newer image for ros:latest dparkar@dupin:~ docker run -it ros
root@a245a8c57fbe:/# docker ps -l
bash: docker: command not found
root@a245a8c57fbe:/# source /opt/ros/melodic/setup.bash
root@a245a8c57fbe:/# rostopic list
ERROR: Unable to communicate with master!
root@a245a8c57fbe:/#

Appreciate any pointers.

Thanks for your question. However we ask that you please ask questions on http://answers.ros.org following our support guidelines: http://wiki.ros.org/Support

ROS Discourse is for news and general interest discussions. ROS Answers provides a forum which can be filtered by tags to make sure the relevant people can find and/or answer the question, and not overload everyone with hundreds of posts.

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Sure thing. I figured out the issue. Thanks !