Support docker

[AntiKnot]

Add Dockerfile, use gosu run specific application as specific user.

What problem does this PR solve?
Issue Number: close #13

What is changed and how it works?

• Dockerfile
• docker-entrypoint.sh
• .dockerignore

[codecov-commenter]

Codecov Report

Merging #14 (fd7aaf6) into master (ea8d923) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##            master       #14   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           16        17    +1     
  Lines          311       321   +10     
=========================================
+ Hits           311       321   +10     

Impacted Files	Coverage Δ
rsserpent/models/__init__.py	100.00% <0.00%> (ø)
rsserpent/models/proxy.py	100.00% <0.00%> (ø)

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[queensferryme]

Thanks for your contribution! Here are two of my concerns:

• The .dockerignore seems incomplete (compared to .gitignore). For example the document build artifact site/ is not excluded from the docker image.
• I don't quite understand gosu and docker-entrypoint.sh, could you provide some context or explanation?

[AntiKnot]

Q1 .dockerignore
I didn't read the code completely, and the files that might be generated by the script were not removed.

Q2 gosu
Avoid using the root user to start the application, and can still handle users and groups after the image is built. gosu can intercept the command matched in cmd and execute it with the specified user instead.

ref.
repo https://github.com/tianon/gosu
demo repo https://github.com/sudo-bmitch/jenkins-docker

Thanks for your contribution! Here are two of my concerns:

• The .dockerignore seems incomplete (compared to .gitignore). For example the document build artifact site/ is not excluded from the docker image.
• I don't quite understand gosu and docker-entrypoint.sh, could you provide some context or explanation?

[AntiKnot]

update .dockerignore, add the content in .gitignore.

PTAL @queensferryme

[queensferryme]

I made quite some changes to the PR:

• use alpine python image, which reduce image size greatly;

  REPOSITORY            TAG          IMAGE ID       CREATED          SIZE
  rsserpent             latest       fea89a26b202   12 minutes ago   235MB
  rsserpent             0.1.3        eba50e4d545f   6 hours ago      1.07GB
  

• use poetry install --no-dev, also reducing image size;
• only copy pyproject.toml, poetry.lock, and rsserpent/, which helps keeping .dockerignore clean;
• use COPY --chown syntax, removing docker-entrypoint.sh.

I am not so sure about the removal of docker-entrypoint.sh. In my understanding, your docker-entrypoint.sh uses gosu to change the permissions of workdir. To me COPY --chown seems like a better solution, since we don't need to introduce gosu and docker-entrypoint.sh.

I will merge if @EurusEurus are okay with these changes.

[AntiKnot]

I made quite some changes to the PR:

• use alpine python image, which reduce image size greatly;

  REPOSITORY            TAG          IMAGE ID       CREATED          SIZE
  rsserpent             latest       fea89a26b202   12 minutes ago   235MB
  rsserpent             0.1.3        eba50e4d545f   6 hours ago      1.07GB
  

• use poetry install --no-dev, also reducing image size;
• only copy pyproject.toml, poetry.lock, and rsserpent/, which helps keeping .dockerignore clean;
• use COPY --chown syntax, removing docker-entrypoint.sh.

I am not so sure about the removal of docker-entrypoint.sh. In my understanding, your docker-entrypoint.sh uses gosu to change the permissions of workdir. To me COPY --chown seems like a better solution, since we don't need to introduce gosu and docker-entrypoint.sh.

I will merge if @EurusEurus are okay with these changes.

LGTM @queensferryme
ps.

$ docker-slim build rsserpent:5.3
rsserpent.slim           latest    1c0fe25629b7   18 seconds ago   115MB

https://dockersl.im/

[queensferryme]

Thanks. I will use docker-slim in github actions.