CodeBuild execution continues after build fails instead of stopping - build

Question

I'm building a CI/CD pipeline using git, codebuild and elastic beanstalk.
During codebuild execution when build fails due to syntax error of a test case, I see codebuild progress to next stage and ultimately go on to produce the artifacts.
My understanding was if the build fails, execution should stop. is this a correct behavior ?
Please see the buildspec below.
version: 0.2
phases:
install:
commands:
- echo Installing package.json..
- npm install
- echo Installing Mocha...
- npm install -g mocha
pre_build:
commands:
- echo Installing source NPM placeholder dependencies...
build:
commands:
- echo Build started on `date`
- echo Compiling the Node.js code
- mocha modules/**/tests/*.js
post_build:
commands:
- echo Build completed on `date`
artifacts:
files:
- modules/*
- node_modules/*
- package.json
- config/*
- server.js

Answer 1

CodeBuild detects build failures by exit codes. You should ensure that your test execution returns a non-zero exit code on failure.
POST_BUILD will always run as long as BUILD was also run (regardless of BUILD's success or failure.) The same goes for UPLOAD_ARTIFACTS. This is so you can retrieve debug information/artifacts.
If you want to do something different in POST_BUILD depending on the success or failure of BUILD, you can test the builtin environment variable CODEBUILD_BUILD_SUCCEEDING, which is set to 1 if BUILD succeeded, and 0 if it failed.

Answer 2

CodeBuild uses the environment variable CODEBUILD_BUILD_SUCCEEDING to show if the build process seems to go right.
the best way I found right now is to create a small script in the install secion and then alway use this like:
phases:
install:
commands:
- echo '#!/bin/bash' > /usr/local/bin/ok; echo 'if [[ "$CODEBUILD_BUILD_SUCCEEDING" == "0" ]]; then exit 1; else exit 0; fi' >> /usr/local/bin/ok; chmod +x /usr/local/bin/ok
post_build:
commands:
- ok && echo Build completed on `date`

Answer 3

The post_build section is run even if the build section might fail. Expanding on the previous answers, you can use the variable CODEBUILD_BUILD_SUCCEEDING in the post_build section of the buildspec.yml file. You can make the post_build section to run if and only if the build section completed successfully. Below is an example of how this can be achieved:
version: 0.2
phases:
pre_build:
commands:
- echo Logging in to Amazon ECR...
- $(aws ecr get-login --no-include-email --region $AWS_DEFAULT_REGION)
- CODEBUILD_RESOLVED_SOURCE_VERSION="${CODEBUILD_RESOLVED_SOURCE_VERSION:-$IMAGE_TAG}"
- IMAGE_TAG=$(echo $CODEBUILD_RESOLVED_SOURCE_VERSION | cut -c 1-7)
- IMAGE_URI="$AWS_ACCOUNT_ID.dkr.ecr.$AWS_DEFAULT_REGION.amazonaws.com/$IMAGE_REPO_NAME:$IMAGE_TAG"
build:
commands:
- echo Build started on `date`
- echo Building the Docker image...
- docker build -t $IMAGE_URI .
post_build:
commands:
- bash -c "if [ /"$CODEBUILD_BUILD_SUCCEEDING/" == /"0/" ]; then exit 1; fi"
- echo Build stage successfully completed on `date`
- docker push $IMAGE_URI
- printf '[{"name":"clair","imageUri":"%s"}]' "$IMAGE_URI" > images.json
artifacts:
files: images.json

Answer 4

add this in build section
build:
on-failure: ABORT

Answer 5

I just wanted to point out that if you want the whole execution to stop when a command fails, you may specify the -e option:
When running a bash file
- /bin/bash -e ./commands.sh
Or when running a set of commands/bash file
#!/bin/bash
set -e
# ... commands

Answer 6

The post_build stage will be executed and the artifacts will be produced. The post_build is good to properly shut down the build environment, if necessary, and the artifacts could be useful even if the build failed. E.g. extra logs, intermediate files, etc.
I would suggest to use post_build only for commands what are agnostic to the result of your build, and properly de-initialise the build environment. Otherwise you can just exclude that step.