Few months ago, I was looking for a way to check the evolution of the structure of one SQLite database I am working on, so I thought having a simple way to get a schema of my database would be a simple solution. A colleague of mine suggested to give SchemaCrawler a try, and so I gave it a go.

I quickly realized that the easiest way to use it on my Debian machine was to use the Docker image, and so I did

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$ docker pull schemacrawler/schemacrawler  

I kept following the guidelines to use it:

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$ docker run \
-v $(pwd):/home/schcrwlr/share \
--name schemacrawler \
--rm -i -t \
--entrypoint=/bin/bash \
schemacrawler/schemacrawler

Briefly, the options used do the following (see man docker run and/or https://docs.docker.com/engine/reference/run):

1. with -v $(pwd):/home/schcrwlr/share Docker creates a bind mount where the current directory ($(pwd)) is mounted in the Docker in the Docker container in home/schcrwlr/share; note that the colon is used for the separation;

2. --name schemacrawler names the container;

3. --rm automatically cleans up the container;

4. -i triggers the interactive mode;

5. -t allocates a pseudo-TTY (teletypewriter), that allows to run an interactive shell;

6. --entrypoint=/bin/bash specifies that we run bash when the container starts.

Then inside te container I used the following lines

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$ schemacrawler \
--server=sqlite --database=share/db/test.db \
--info-level=minimum \
--command=schema --output-format=png --output-file=./asset./assets/graph_min.png

I think the option names are pretty clear here. The only thing I would like to stress is that to directly obtain the graphic from the container we need to save the figure to share where the current directory has been mounted as explain above. This command line yielded the following image for my SQLite database:

As I think the level of details was not high enough, I used the maximum level of details by doing

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$ schemacrawler \
--server=sqlite --database=share/test.db \
--info-level=maximum \
--command=schema --output-format=png --output-file=./asset./assets/graph_max.png

which return the following .png image

which is the kind of schema I actually needed! Pretty neat, isn’t it?