Allow /version to be defined by environment variables

[AetherUnbound]

Fixes

This is necessary for continued work on https://github.com/WordPress/openverse-infrastructure/issues/175

Description

This PR makes a few changes to the nginx target image for the API in order to prevent the need for mounting any files into the docker container. Previously, the /version was configured to return the contents of a version.json file. This file was created during deployment and mounted into the nginx image:

https://github.com/WordPress/openverse-infrastructure/blob/369d7858636797de276dbfc299b90b822a5ac527/modules/services/openverse-api/init.tpl#L79-L85

The issue with this is that we are trying to avoid the need for mounting anything into our API-related containers. This was the last necessary item that was being mounted. You can see that this endpoint is not served by the API by running just up and visiting http://localhost:50280/version.

I've altered the image to construct the response from /version using environment variables rather than reading from a file on-disk. This involved a few changes to the environment substitution setup, which I was unfamiliar with (there are seemingly no references to NGINX_ENVSUBST_FILTER on GitHub where it's being defined by anyone other than us!). I added a few more comments to try and provide reference to what was being used, and where.

I also addressed an issue wherein we were erroneously referencing variables inside the nginx template with \$ rather than just $. This was an artifact of constructing the config inside of the init.tpl file during deployment (which required that we escape the $ character since it was used for its own interpolation). This was producing logs that looked like the following (note the extra \ characters before field values):

{"time_local":"\29/Nov/2022:00:33:08 +0000","remote_addr":"\172.17.0.1","remote_user":"\","request":"\GET / HTTP/1.1","status": "\400","host_header": "\localhost","body_bytes_sent":\155,"request_time":"\0.020","http_referrer":"\","http_user_agent":"\Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:106.0) Gecko/20100101 Firefox/106.0","upstream_response_time":\0.020,"http_x_forwarded_for":"\"}

Lastly, I added a just recipe for running the nginx image locally with some suggestions on how to test that it works.

Testing Instructions

1. Before checking out this branch, verify that the API returns a 404 on http://localhost:50280/version after running just up
2. Run just nginx
3. Visit http://localhost:9090/static/admin/css/base.css and verify that results are returned (this should be from api.openverse.engineering)
4. Visit http://localhost:9090/version and verify that you receive something similar to the following:

{

    "release": "47521cd5b288c35afaf0f996015e8122bbc1ccf8",
    "environment": "local"

}

Checklist

• My pull request has a descriptive title (not a vague title like Update index.md).
• My pull request targets the default branch of the repository (main) or a parent feature branch.
• My commit messages follow best practices.
• My code follows the established code style of the repository.
• I added or updated tests for the changes I made (if applicable).
• I added or updated documentation (if applicable).
• I tried running the project locally and verified that there are no visible errors.

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[AetherUnbound]

@sarayourfriend I've added you as a reviewer since you were the original author of #990 and are most familiar with the code!

[github-actions]

API Developer Docs Preview: Ready

https://wordpress.github.io/openverse-api/_preview/1015

Please note that GitHub pages takes a little time to deploy newly pushed code, if the links above don't work or you see old versions, wait 5 minutes and try again.

You can check the GitHub pages deployment action list to see the current status of the deployments.

[sarayourfriend]

Ah, thank you for catching this! I totally forgot about this requirement when working on the original issue. Thanks for fixing the logging as well, I had not noticed that.

[sarayourfriend]

We'll need to be sure to pass this environment variable in the ECS configuration as well, once we get there. That at least is constant for the environment, so not an issue.

[AetherUnbound]

Yes, same with the DJANGO_NGINX_GIT_REVISION!

[sarayourfriend]

Regarding NGINX_ENVSUBST_FILTER, btw... I think I ended up having to read the various entrypoint scripts that the Nginx image comes with to discover this! It is not documented in the README for the image on docker hub 😢

[AetherUnbound]

Regarding NGINX_ENVSUBST_FILTER, btw... I think I ended up having to read the various entrypoint scripts that the Nginx image comes with to discover this! It is not documented in the README for the image on docker hub 😢

That's exactly what I did as well! And what I ended up having to link to. I even had to play around with awk a bit locally to figure out if we could use a prefix or if we had to match the whole variable name 😅 definitely leaves something to be desired!

[stacimc]

Thank you for the testing instructions! LGTM 😄