How to pass environment variable received from GitHub actions - docker

Question

In my action.yml I defined an input:
name: 'test action'
author: Param Thakkar
description: 'test'
inputs:
test_var:
description: 'A test variable'
required: true
runs:
using: 'docker'
image: 'Dockerfile'
And in my workflow I passed the test_var:
name: CI
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- name: Test the GH action
uses: paramt/github-actions-playground#master
with:
test_var: "this is just a test"
So there should be an environment variable that's created when the workflow runs, right? But when I run this short python script:
import os
print(os.getenv('TEST_VAR'))
print("It works!")
exit(0)
It prints:
None
It works!
I think that I have to pass the ENV variable through my Dockerfile... Right now my Dockerfile looks like this:
FROM python:latest
# Add files to the image
ADD entrypoint.py /entrypoint.py
ADD requirements.txt /requirements.txt
# Save ENV var in a temp file
RUN $TEST_VAR > /temp_var
# Install dependencies and make script executable
RUN pip install -r requirements.txt
RUN chmod +x entrypoint.py
RUN echo "temp var: "
RUN cat /temp_var
# Run script with the ENV var
ENTRYPOINT export TEST_VAR="$TEST_VAR"; /entrypoint.py
But the variable isn't echoed and isn't passed to the pythons script either.. am I missing something? When I tried to set my $TEMP_VAR to a random piece of string, it is sent through to the Python script. Is this a mistake on my behalf or is the GitHub action not working as intended?
Here's the link to the test repo

Answer 1

I think you are trying to read the wrong environment variable name. GitHub Actions adds INPUT_ to the name of the input variable. So try the following:
print(os.getenv('INPUT_TEST_VAR'))
From the documentation:
When you specify an input to an action in a workflow file or use a
default input value, GitHub creates an environment variable for the
input with the name INPUT_. The environment variable
created converts input names to uppercase letters and replaces spaces
with _ characters.
For example, if a workflow defined the numOctocats and octocatEyeColor
inputs, the action code could read the values of the inputs using the
INPUT_NUMOCTOCATS and INPUT_OCTOCATEYECOLOR environment variables.
https://help.github.com/en/articles/metadata-syntax-for-github-actions#inputs

Answer 2

A bit late but for the next one, you can also use the env field :
name: CI
on: [push]
jobs:
build:
runs-on: ubuntu-latest
steps:
- name: Test the GH action
uses: paramt/github-actions-playground#master
env:
test_var: "this is just a test"
which will be included during the creation of your docker and pass without the prefix INPUT_

Answer 3

Keep env vars secret by specifying them in Settings -> Secrets in the repo, and then calling them in the workflow:
For example, consider a workflow that runs an R script followed by a Python script. First, in .github/workflows/my_job.yml notice the MY_VAR variable, which points to a stored secret with ${{ secrets.MY_VAR}}. The rest is standard code (run on cron, specify Ubuntu OS and Docker image, define workflow steps).
on:
schedule:
- cron: '0 17 * * *'
jobs:
my_job:
name: my job
env:
MY_VAR: ${{ secrets.MY_VAR }}
runs-on: ubuntu-18.04
container:
image: docker.io/my_username/my_image:my_tag
steps:
- name: checkout_repo
uses: actions/checkout#v2
- name: run some code
run: bash ./src/run.sh
Next, in the scripts that compose your workflow, you can access the env var specified in the workflow file above as you would locally.
For example, in the repo, let's assume src/run.sh calls an R script followed by a Python script.
In R access the env var and store as an object:
my_var <- Sys.getenv("MY_VAR")
.
.
.
In Python access the env var and store as an object:
import os
my_var = os.getenv("MY_VAR")
.
.
.
See the docs here.

Answer 4

In my case, none of the answers worked. Here's how I fixed it.
---
name: Build and Push Docker Image to AWS ECR
on:
push:
branches: [ master ]
env:
FOO: '${{ secrets.FOO }}'
jobs:
build-and-push:
name: Build Project and Push to AWS ECR
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/checkout#v2
...
- name: Build and Push to AWS ECR
id: build-image
env:
ECR_REGISTRY: ${{ steps.login-ecr.outputs.registry }}
run: |
docker build --build-arg FOO=$FOO -t $ECR_REGISTRY/crew-charge-app:latest .
docker push $ECR_REGISTRY/crew-charge-app:latest
I first had to get the FOO variable from github secrets using ${{secrets.FOO}} then pass it onto the docker file using docker build --build-arg FOO=$FOO --build-arg BAR=$BAR -t .
Then inside the docker file I had to declare both as an ARG and ENV to be available at all times.
FROM node:14
ARG FOO=${FOO}
ENV FOO=${FOO}
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app
COPY package.json /usr/src/app
RUN yarn install
COPY . /usr/src/app
RUN FOO=$FOO yarn build
EXPOSE 80
CMD ["yarn", "start" ]
Important part was to RUN FOO=$FOO yarn build because setting the ENV alone doesn't pass it onto the container.