Codebuild Workflow with environment variables - bash

Question

I have a monolith github project that has multiple different applications that I'd like to integrate with an AWS Codebuild CI/CD workflow. My issue is that if I make a change to one project, I don't want to update the other. Essentially, I want to create a logical fork that deploys differently based on the files changed in a particular commit.
Basically my project repository looks like this:
- API
-node_modules
-package.json
-dist
-src
- REACTAPP
-node_modules
-package.json
-dist
-src
- scripts
- 01_install.sh
- 02_prebuild.sh
- 03_build.sh
- .ebextensions
In terms of Deployment, my API project gets deployed to elastic beanstalk and my REACTAPP gets deployed as static files to S3. I've tried a few things but decided that the only viable approach is to manually perform this deploy step within my own 03_build.sh script - because there's no way to build this dynamically within Codebuild's Deploy step (I could be wrong).
Anyway, my issue is that I essentially need to create a decision tree to determine which project gets excecuted, so if I make a change to API and push, it doesn't automatically deploy REACTAPP to S3 unnecessarliy (and vica versa).
I managed to get this working on localhost by updating environment variables at certain points in the build process and then reading them in separate steps. However this fails on Codedeploy because of permission issues i.e. I don't seem to be able to update env variables from within the CI process itself.
Explicitly, my buildconf.yml looks like this:
version: 0.2
env:
variables:
VARIABLES: 'here'
AWS_ACCESS_KEY_ID: 'XXXX'
AWS_SECRET_ACCESS_KEY: 'XXXX'
AWS_REGION: 'eu-west-1'
AWS_BUCKET: 'mybucket'
phases:
install:
commands:
- sh ./scripts/01_install.sh
pre_build:
commands:
- sh ./scripts/02_prebuild.sh
build:
commands:
- sh ./scripts/03_build.sh
I'm running my own shell scripts to perform some logic and I'm trying to pass variables between scripts: install->prebuild->build
To give one example, here's the 01_install.sh where I diff each project version to determine whether it needs to be updated (excuse any minor errors in bash):
#!/bin/bash
# STAGE 1
# _______________________________________
# API PROJECT INSTALL
# Do if API version was changed in prepush (this is just a sample and I'll likely end up storing the version & previous version within the package.json):
if [[ diff ./api/version.json ./api/old_version.json ]] > /dev/null 2>&1
## then
echo "🤖 Installing dependencies in API folder..."
cd ./api/ && npm install
## Set a variable to be used by the 02_prebuild.sh script
TEST_API="true"
export TEST_API
else
echo "No change to API"
fi
# ______________________________________
# REACTAPP PROJECT INSTALL
# Do if REACTAPP version number has changed (similar to above):
...
Then in my next stage I read these variables to determine whether I should run tests on the project 02_prebuild.sh:
#!/bin/bash
# STAGE 2
# _________________________________
# API PROJECT PRE-BUILD
# Do if install was initiated
if [[ $TEST_API == "true" ]]; then
echo "🤖 Run tests on API project..."
cd ./api/ && npm run tests
echo $TEST_API
BUILD_API="true"
export BUILD_API
else
echo "Don't test API"
fi
# ________________________________
# TODO: Complete for REACTAPP, similar to above
...
In my final script I use the BUILD_API variable to build to the dist folder, then I deploy that to either Elastic Beanstalk (for API) or S3 (for REACTAPP).
When I run this locally it works, however when I run it on Codebuild I get a permissions failure presumably because my bash scripts cannot export ENV_VAR. I'm wondering either if anyone knows how to update ENV_VARIABLES from within the build process itself, or if anyone has a better approach to achieve my goals (conditional/ variable build process on Codebuild)
EDIT:
So an approach that I've managed to get working is instead of using Env variables, I'm creating new files with specific names using fs then reading the contents of the file to make logical decisions. I can access these files from each of the bash scripts so it works pretty elegantly with some automatic cleanup.
I won't edit the original question as it's still an issue and I'd like to know how/ if other people solved this. I'm still playing around with how to actually use the eb deploy and s3 cli commands within the build scripts as codebuild does not seem to come with the eb cli installed and my .ebextensions file does not seem to be honoured.

Answer 1

Source control repos like Github can be configured to send a post event to an API endpoint when you push to a branch. You can consume this post request in lambda through API Gateway. This event data includes which files were modified with the commit. The lambda function can then process this event to figure out what to deploy. If you’re struggling with deploying to your servers from the codebuild container, you might want to try posting an artifact to s3 with an installable package and then have your server grab it from there.