Dry-Run Mode

Preview what jbundle will do without executing anything.

Usage

jbundle build --input ./my-app --output ./dist/app --dry-run

What It Shows

[dry-run] Build plan for ./my-app → ./dist/app

  Build system:  DepsEdn (clojure -T:build uber)
  Target:        Target { os: Linux, arch: X86_64 }
  JDK version:   21
  JDK source:    cached ✓
  Modules:       auto-detect (jdeps)
  Runtime:       create via jlink
  Profile:       cli
  Shrink:        enabled
  AppCDS:        enabled
  CRaC:          disabled
  JVM args:      -Xmx512m

  No actions taken.

Field	Description
Build system	Detected build tool and command that would run
Target	OS and architecture of the output binary
Cross-compile	Shown when target differs from host platform
JDK version	Which JDK version will be used
JDK source	Whether the JDK is cached, local (--java-home), or needs download
Modules	Auto-detect via jdeps or manual override
Runtime	New via jlink or reusing existing (--jlink-runtime)
Profile	cli (fast startup) or server (throughput)
Shrink/AppCDS/CRaC	Feature toggles
JVM args / Build args	Extra arguments, if any

When to Use

Validating config before a long build:

# Check that jbundle.toml is picking up the right settings
jbundle build --input . --output ./app --dry-run

Verifying cross-compilation setup:

# Confirm host + target JDK strategy
jbundle build --input . --output ./app --target linux-x64 --dry-run

Debugging CI:

# Add to your CI pipeline before the real build
jbundle build --input . --output ./dist/app --dry-run
jbundle build --input . --output ./dist/app

Checking build system detection:

# Repos with multiple build files (deps.edn + project.clj)
jbundle build --input ./my-project --output ./app --dry-run

Configuration

Dry-run is CLI-only — there's no jbundle.toml equivalent. All other config options (--java-version, --profile, --target, etc.) work normally with --dry-run to preview their effect.