I am trying to build a Docker image for one of my sources and getting following error:

(pants) [root@9a5752857756 pants-training]# ./pants package src/server:docker
09:52:28.41 [INFO] Completed: Building dockerfile_parser.pex from dockerfile-parser_default.lock
09:52:32.72 [INFO] Completed: Building docker image docker:latest
09:52:32.73 [WARN] Docker build failed for `docker_image` src/server:docker. The src/server/Dockerfile have `COPY` instructions where the source files may not have been found in the Docker build context.

The following files were not found in the Docker build context:

  * ./3rdparty/requirements.txt
  * ./src/server/


09:52:32.73 [ERROR] 1 Exception encountered:

  ProcessExecutionFailure: Process 'Building docker image docker:latest' failed with exit code 1.
stdout:

stderr:
Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?



Use `--no-process-cleanup` to preserve process chroots for inspection.

(pants) [root@9a5752857756 pants-training]#

My source can be found here. It seems like I need to add some dependencies to the

docker_image()

target which I already tried but it did not work. Could anyone please help me with that?

yes, your

docker_image

target would need to define explicit dependencies on the requirements file and the

python_sources

target to build as you’ve defined it

I already have the dependency on

python_sources()

target:

dependencies=[":server"]

line #20 in

src/server/BUILD

Thanks Dan. +1 to considering using

pex_binary

with Docker. This blog explains the integration: https://blog.pantsbuild.org/pants-pex-and-docker/

My current focus is to be able to build a Docker image successfully. The part where I need to consider using pex/python source comes later for me.

Re what you currently have, there is a major gotcha that we only add

dependencies

for `file`/`files` targets and then anything that can be `package`d, like a

pex_binary

target. So, unfortunately, the

python_sources

dependency gets ignored -- big gotcha If you want to stick with the current approach of copying those two files, you'll need to create

file

/

files

targets for the relevant code. For example:

files(name="as_files", sources=["*.py"])

docker_image(name="docker", dependencies=[":as_files", "3rdparty:requirements_file"])

Thanks @hundreds-father-404, I read about the Docker context and its expectation of a

file

/

files

target in the Pants Docker docs but wasn’t sure where do I define those targets? Moreover, I then read about these two target types and it said that any files “that lives outside of code packages” and that confused me further. For my first question, do I define a file target each in

3rdparty/BUILD

and

src/server/BUILD

for

requirements.txt

file and for

.py

file, respectively?

For my first question, do I define a file target each in 3rdparty/BUILD and src/server/BUILD for requirements.txt file and for .py file, respectively?

Yeah, exactly. And keep all your existing targets you have

Ok, so I was able to define the

file

targets successfully but then ran into an error (attached). This seems more of a python package installation error and not Pants error but just wanted to share and request if you are able to pull the latest source and try

./pants package src/server:docker

?

yeah I think that is a Python error. It's because you put

grpc

in your

requirements.txt

, which we don't want. That's a bad package and

grpcio

needs to be used instead. So, delete

grpc

Then, to work around Pants's issue complaining it can't find

grpc

, you will want to set in

3rdparty/BUILD

in the

python_requirements

target the field

module_mapping={"grpcio": ["grpc"]}

-- you can delete that once we do the 2.12 release today

Let me try.

Yeah, the

module_mapping

solution is the correct one. You are teaching Pants that the requirement named

grpcio

provides the module

grpc

The Docker image doesn’t have the required stubs in it. Following is the

docker-image()

target definition:

docker_image(

name="docker",

dependencies=[":server_source_code", "3rdparty:python_requirements"]

)

The dependencies are those files that need to be copied explicitly in the image. The

server_source_code

target has import statements to import protobufs. Why aren’t the stubs generated?

Pardon, I was in meetings. Ah, so I actually don't think there's currently a way to get the generated Protobuf files into the Docker image. The only hack I could think of is using

export-codegen

and manually saving the files to disk, but that goes against the point of Pants's codegen (ensuring you always have up-to-date files and don't need to check them in) +1 that the Docker backend really works substantially better when combining it with

pex_binary

. The Pex will already include the generated code for you, for example

Ok, and packing a library to an image?

What do you intend to do with the image? PEXes are fairly flexible: you can set an entry point so that it's runnable, or leave off an entry point where running it opens a REPL with the relevant code in PYTHONPATH, or even call

unzip

on the file. PEXes are basically runnable zip files of Python code

Yeah I understand that. Ok, let me first figure out if I need to pack a lib or a Pex to the Docker and get back to you. In the meanwhile, I am having probs in pushing image to the registry. I am working thru that.