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Tini - A tiny but valid `init` for containers
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=============================================
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[](https://travis-ci.org/krallin/tini)
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Tini is the simplest `init` you could think of.
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All Tini does is spawn a single child (Tini is meant to be run in a container),
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and wait for it to exit all the while reaping zombies and performing
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signal forwarding.
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Using Tini
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----------
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*NOTE: There are [pre-built Docker images available for Tini][10]. If
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you're currently using an Ubuntu or CentOS image as your base, you can use
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one of those as a drop-in replacement.*
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Add Tini to your container, and make it executable. Then, just invoke Tini
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and pass your program and its arguments as arguments to Tini.
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In Docker, you will want to use an entrypoint so you don't have to remember
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to manually invoke Tini:
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# Add Tini
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ENV TINI_VERSION v0.3.4
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ADD https://github.com/krallin/tini/releases/download/${TINI_VERSION}/tini /tini
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RUN chmod +x /tini
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ENTRYPOINT ["/tini", "--"]
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# Run your program under Tini
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CMD ["/your/program", "-and", "-its", "arguments"]
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# or docker run your-image /your/program ...
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Note that you *can* skip the `--` under certain conditions, but you might
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as well always include it to be safe. If you see an error message that
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looks like `tini: invalid option -- 'c'`, then you *need* to add the `--`.
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Arguments Tini itself are passed like so: `/tini -v -- /your/program`.
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The only supported argument at this time is `-v`, for extra verbosity (you can
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pass it up to 4 times, e.g. `-vvvv`).
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*NOTE: The binary linked above is a 64-bit dynamically-linked binary.*
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### Existing Entrypoint ###
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Tini can also be used with an existing entrypoint in your container!
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Assuming your entrypoint was `/docker-entrypoint.sh`, then you would use:
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ENTRYPOINT ["/tini", "--", "/docker-entrypoint.sh"]
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### Size Considerations ###
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Tini is a very small file (in the 10KB range), so it doesn't add much weight
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to your container.
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### Building Tini ###
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If you'd rather not download the binary, you can build Tini by just running
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`make` (i.e. there is no `./configure` script).
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Understanding Tini
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------------------
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After spawning your process, Tini will wait for signals and forward those
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to the child process, and periodically reap zombie processes that may be
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created within your container.
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When the "first" child process exits (`/your/program` in the examples above),
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Tini exits as well, with the exit code of the child process (so you can
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check your container's exit code to know whether the child exited
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successfully).
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Debugging
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---------
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If something isn't working just like you expect, consider increasing the
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verbosity level (up to 4):
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tini -v -- bash -c 'exit 1'
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tini -vv -- true
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tini -vvv -- pwd
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tini -vvvv -- ls
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[10]: https://github.com/krallin/tini-images
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