I need to get all release tags from remote git repository. Anyone have any ideas how could I do it using grunt or node?
You need clarify your question a bit, since it a bit unclear, is repository is local or remote, for example. This makes difference.
But I believe I can describe approach to you, so you can decide what to do (or what to ask next);
If you have local repository, you have folder there called .git in contains all information about source code. In most cases this information is in plain text and could be easily accessed via standard node tools.
For example, look on the contents of the following folder: .git/refs:
* You will find all local branches as a files in subfolder .git/refs/heads;
* All remote branches current repository aware of are in .git/refs/remotes/origin (more remote end-points you have, more you will find subfolders in that folder);
* Tags are in .git/refs/tags;
Read listing of the folder and you will get the names of needed tags.