Question about building a pex into a Docker image. I need to reference some files in my repo - the code does things like

shutil.copytree(src/services/app/static, etc)

. This works fine when I run the pex target, but once I build a Docker image from it I get

FileNotFoundError: [Errno 2] No such file or directory: 'src/services/app/static'

. I tried adding the directory as both a

files

and

resources

and having my docker target depend on it, but that didn't help. What's the magic I'm looking for here? Am I not referencing it right in the Docker image, or are those files not going to be there at all without some extra work? For reference, my dockerfile itself is simply

FROM python:3.8
ENTRYPOINT ["/bin/app.pex"]
COPY src.services.app.scripts/app.pex /bin

did you also add a

COPY src/ src

to your Dockerfile? otherwise the files would be in the docker build context, but not available to your pex file when running in the container.

src/ src

seemed to have worked, thank you very much!

I am having a similar problem. My assets reside in

assets/

, docker in

src/python/service_name/Dockerfile,

and my pex has a dependency on the right assets. It doesn't seem like assets are getting copied automatically, and trying:

COPY /assets assets

in docker isn't working. Any ideas?

@glamorous-nail-59544 do you mean?:

COPY assets/ assets

Note the `/`is in a different spot in my example than in yours and my example aligns with the conversation above.

I actually tried all combinations

The repo structure should be irrelevant in the end, Pants can work with most any layout.

my pex has a dependency on the right assets.

How do you spell the dependency? For the files to live in the PEX the dependency must be on a

resources

target and not a `files`target - for not good reasons, but it's true today anyhow.

My file deps are automatically inferred from code, and verified that using

./pants dependencies --transitive.

And yes I am aware that they are not packaged in the pex, but I thought docker target will be smarter and copy them into the correct relative path.

So, can you answer my question though? Are the dependencies on resources targets or file targets?

file

Ok, would you mind trying a switch to resources then?

I have a lib that requires some files and it is using

open

which I don't think works with resource? Also, something interesting, adding the assets dep explicitly worked!

docker_image(name="service_name", source="Dockerfile", dependencies=["assets:files"])

It does work with resource

will give resource a try, but not sure why explicit dependency is required here!

How does Pants infer the dependency? Most dependency inference is via analysis of import statements. Surely you don't import these assets.

transitive deps without explicit declaration

assets/DejaVuSansCondensed.ttf:files
assets/i18n/BUILD:files
assets/i18n/responses.en.yml:files

with explicit declaration

assets/BUILD:files
assets/DejaVuSansCondensed.ttf:files
assets/cv.docx:files
assets/i18n/BUILD:files
assets/i18n/responses.en.yml:files
assets/test_image.jpg:files

I am using files cause this lib wasn't working with resource based assets

Ok, my question though was how that 1st set is being inferred. Generally Pants can only infer dependencies by following import statements. Presumably 0 of these lead to assets/*.

I remember reading that it can do this and there is a config to define number of separators before pants tries to infer them, can't find where I read it! Will check the above

Don't be confused by `resources`being named "resources". You do not need to use

importlib.resources

- for example - to access files included via the Pants `resources`concept.

Found it https://www.pantsbuild.org/docs/reference-python-infer#assets

Ok. Yeah - those sorts of infers are iffy and only work a small portion of the time in general.

They did pretty well with

files

target

The target type should not be relevant.

well, I mean using relative path, might work with

resources

as well, but as you mentioned above, if I use file I will loose he path which will make it hard to infer

Ah gotcha. I understand now. I personally would never use / rely on asset inference, but if you like using it, your issue with resources makes sense.

I love everything infer about pants, it feels magical this way. I would love to see this also be ported to docker build target if possible! Anyhow, thanks for the info, will examine using resources and evaluate which is better for my and my team's mental health 🙂

Asset inference is somewhat magical, but it is a necessary evil to have virtually no explicit dependencies, which is a much worse evil

That's definitely in the eye of the beholder.

So @glamorous-nail-59544 both resources and files are inferred, but they are inferred differently. Files are assumed to be loaded relative to build root (which is what you must be doing). Resources are assumed to be loaded relative to the file loading them (as if using importlib with

__name__

)

I am an engineer; so eye of the beholder as I said,. I'd never turn asset inference on. I also don't use the default source root magic for the same reason - I declare mine explicitly.

@bitter-ability-32190 my assets are in

assets

dir in the repo root. I couldn't find a way to load them using

importlib

or

pkgutil

, so can't get pants to infer them 🤷‍♂️

Yeah those are likely best treated as "files"