Is there an environment variable in Docker Hub Automated Builds that tells you the location of the repo root?

Question

Let's say my repo is called X. I have these files

• X/worker/Dockerfile
• X/worker/hooks/build

Inside Dockerfile, I have this command COPY worker/requirements.txt ./requirements.txt

Inside build file, I have this command docker build -f $DOCKERFILE_PATH -t $IMAGE_NAME .

I use Docker Hub Automated Builds feature to build the image based on the build file I have. I set Dockerfile location to worker/Dockerfile and build context to /.

There is an error saying that worker directory is not found when building. I guessed that it's because the current directory on the cloud machine is not set to X. So I tried to put pwd into build file to see the current directory. The result is /src/bq2wmtsfppaqsxh3krqkqay/worker. So my guess is right. It seems that docker rename my repo to a random string and cd into worker directory when building the image.

There are 2 potential solutions:

1. I want it to not cd into worker directory because I set build context to . in the build command which I want it to refer to X not X/worker. How can I achieve that?
2. Instead of setting build context to ., maybe there is a special environment variable that will tell me where X locates. In this case I want a string variable that stores /src/bq2wmtsfppaqsxh3krqkqay, is there such a variable that I can use as build context in the build command?

Also is there an example of the exact build command used by docker to do Automated Builds? If I can see the exact build command they use, maybe I'll be able to modify it to suit my needs. I expect it to follow this format: docker build ...