Setup for Vibe-Coding AWS Corretto JDK 24 + Maven with OpenAI Codex

I’m just exploring the incredible tool that is OpenAI’s new Codex: https://chatgpt.com/codex

With Codex you connect a coding agent to a GitHub repo, then iteratate using a new agent which works in a containerised cloud environment. At the end the agent creates a Pull Request on a new branch for you to review and merge. So cool! The agent isn’t perfect yet, and makes mistakes, but it’s definitely worth testing out. I like the paradigm and the user experience feels right.

If you are using Java/Maven, you will probably hit the same hurdles I did and need to customise the environment Setup script with something like this:

#!/usr/bin/env bash
set -euo pipefail

# Prepare Ubuntu for installing AWS Corretto JDK via APT
wget -O - https://apt.corretto.aws/corretto.key | sudo gpg --dearmor -o /usr/share/keyrings/corretto-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/corretto-keyring.gpg] https://apt.corretto.aws stable main" | sudo tee /etc/apt/sources.list.d/corretto.list

sudo apt-get update
sudo apt-get install -y -q java-24-amazon-corretto-jdk maven nano
java -version
mvn -v

# Configure the Java truststore to trust the proxy certificate when downloading maven dependencies
sudo keytool -importcert \
  -noprompt \
  -storepass changeit \
  -cacerts \
  -alias codex-proxy \
  -file "$CODEX_PROXY_CERT"

# Configure Maven to use Codex proxy
mkdir -p ~/.m2
cat > ~/.m2/settings.xml <<EOF
<settings>
  <proxies>
    <proxy>
      <id>codexProxy</id>
      <active>true</active>
      <protocol>http</protocol>
      <host>proxy</host>
      <port>8080</port>
    </proxy>
  </proxies>
</settings>
EOF

The script installs my preferred JDK (AWS Corretto 24), then adds the environment’s HTTP proxy SSL cert to Java’s trusted certificate store. Finally it configures maven to use the proxy when downloading dependencies.

I allowed the agent limited whitelist access to the Internet (which by default includes the public Maven repos):

Alternatively you could add a final line to download the maven dependencies during the Setup script and cut the agent off from the Internet altogether:

# Download all dependencies (while internet is active)
mvn dependency:go-offline -B

Using either approach you’ll then be able to build and run your Java project on the JDK of your choice with Maven!

Happy vibe-coding!