fix(java): Add retry logic for transient SDKMAN bootstrap failures

[V-Subhankar-infy]

Fix: Java feature transient SDKMAN 503 failures

Problem

The Java feature fails intermittently when get.sdkman.io returns HTTP 503 during bootstrap/install. No recovery mechanism exists, causing build failures and manual reruns. Reported at #1684 & #454.

Error: curl: (22) The requested URL returned error: 503

Solutions

1. Add Retry Logic (Temporary)

5 attempts, 10-second intervals (~50s total). Mirrors existing patterns in git, python, ruby, terraform features.

• Minimal: 30 lines added
• Proven: Same approach works in other features
• Only tolerates transient failures (doesn't solve chronic SDKMAN downtime)

2. Switch to Alternative Package Source (Permanent)

Use OS package manager (apt install openjdk-*) or direct Temurin downloads instead of SDKMAN.

• Limited to OpenJDK/LTS versions (no GraalVM, Corretto, Microsoft Java)
• Breaks reproducibility (different JVMs per distro)
• High maintenance: per-distro logic, test matrix explosion

Current Choice: Retry Logic

Why temporary over permanent?

• No 100% viable alternative (all permanent solutions lose significant feature coverage)
• Problem is transient, not systemic (intermittent 503s, not chronic downtime)
• Maintenance burden unjustified by severity
• SDKMAN is still the best solution when working

Strategy: Monitor for 2-3 weeks post-merge. If failures persist, revisit permanent solutions.

Implementation

Added to src/java/install.sh:

run_with_retries() {
    local max_attempts="$1" wait_seconds="$2" operation="$3" attempt=1
    shift 3
    until "$@"; do
        [ "${attempt}" -ge "${max_attempts}" ] && return 1
        echo "(*) ${operation} failed on attempt ${attempt}. Retrying in ${wait_seconds}s..."
        attempt=$((attempt + 1))
        sleep "${wait_seconds}"
    done
}

install_sdkman_cli() {
    bash -o pipefail -c 'curl -sSL "https://get.sdkman.io?rcupdate=false" | bash'
}

Applied to:

• SDKMAN bootstrap: run_with_retries 5 10 "Installing SDKMAN" install_sdkman_cli
• SDK install: run_with_retries 5 10 "Installing ${install_type} ${requested_version} via SDKMAN" ...

Total change: ~30 lines

Testing & Validation

Deterministic proof:

• Baseline (unpatched + injected 503): Failed at 12s
• Patched (same injected 503): Recovered at 79s with retry evidence in logs
• No regression on healthy path: ~84-85s (same as before)

# Test command
devcontainer features test -f java --skip-scenarios -i ubuntu:noble --log-level info .

# Watch for retries
grep -i "retrying\|failed on attempt" logs

Impact

• Reduces the transient SDKMAN 503s error due to added waiting.
• No impact on user performance.
• No Performance overhead.
• No change in support of Java versions/distributions

[Copilot]

Pull request overview

This PR aims to reduce intermittent failures in the Java feature by adding retry logic around SDKMAN installation/SDK-based installs, addressing transient HTTP 503 errors during SDKMAN bootstrap and candidate downloads.

Changes:

• Added a run_with_retries helper and applied it to SDKMAN bootstrap and sdk install operations in src/java/install.sh.
• Bumped the Java feature version to 1.8.1.
• Updated the “latest” Java test expectation in test/java/install_latest_version.sh.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/java/install.sh	Introduces and applies retry logic for SDKMAN bootstrap and SDK-based installs.
src/java/devcontainer-feature.json	Bumps feature version to reflect behavioral change.
test/java/install_latest_version.sh	Updates latest-version assertion (and currently contains a quoting bug in the hello-world check).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.