Keep your stuff up to date

best practices java javascript

Every codebase depends on multiple external libraries. It is a good idea to stay up to date with external dependencies. It is important to update all security related stuff and it might be helpful or fun to use latest features. I’m going to share my way of staying up to date with external dependencies in maven, gradle and npm.


The first thing which in my opinion is crucial to stay up to date is to create automated checker. The best place for this will be your CI tool. Create Jenkins plan (or project in whatever CI tool you are using) which will fail when there are outdated libraries. Automated tool will nudge you every time there is an external library that should be updated. Without notification from the CI no one is going to execute dependency check manually on a day to day development especially when there is more work than days before the deadline.

I don’t recommend failing every time there is outdated library because it will be annoying to update frontend libraries every second hour ;) Failing when there is more than X outdated libraries is actually good idea. Just remember to configure X to be an acceptable value. No one is going to update 15 frontend libraries at once because 4 of them will have different API after bugfix release (…), but someone might update 2 or 3 of them once in a while.

The last advice which is the game changer I’ve got is to configure it as commit hook not as scheduled task. When it is scheduled and it fails in the middle of the night then every developer will ignore. But when the build fails after your commit then you feel responsible for it and try to fix it to keep board green (broken windows theory).


When using npm as dependencies manager it is very simple to find out outdated packages - just run npm outdated (docs) and you are good to go. Sample outdated command output

Package     Current  Wanted  Latest  Location
angular       1.5.9   1.5.9   1.6.3  dependenices-update
lodash        3.6.0   3.6.0  4.17.4  dependenices-update
mocha         3.1.0   3.1.0   3.2.0  dependenices-update

When you CI instance is configured you might want to create something more ‘sophisticated’:


npm -s install

OUTDATED_PACKAGES=`npm -s outdated | grep -v beta | grep -v rc`

  echo "There is $OUTDATED_PACKAGES_COUNT outdated dependencies!"
  printf '%b\n\n' "$OUTDATED_PACKAGES"

You call this script with a parameter which will be the maximum number of acceptable outdated dependencies. The script is very simple and will exclude most of the beta and release candidates.



To find outdated dependencies in gradle you can use gradle versions plugin. Sample output from versions plugin:

$> ./gradlew dependencyUpdates

: Project Dependency Updates (report to plain text file)

The following dependencies are using the latest milestone version:
 - com.github.ben-manes:gradle-versions-plugin:0.14.0

The following dependencies have later milestone versions:
 - org.apache.commons:commons-lang3 [3.4 -> 3.5]
 - junit:junit [3.8.1 -> 4.12]
 - org.springframework:spring-core [3.2.4.RELEASE -> 4.3.7.RELEASE]

The output is a bit complex, but luckily there are also other formats (JSON and XML) which can be generated using -DoutputFormatter=json switch. Output report will be generated in build/dependencyUpdates directory. Jason support in bash doesn’t exists, but you can use jq for working with json in bash (sudo apt-get install jq).

Or you can ask google for some advice on how to use sed and improvise:


./gradlew -DoutputFormatter=json dependencyUpdates > /dev/null 2>&1

OUDATED_DEPENDENCIES_COUNT=`sed -n -e '/The following dependencies have later/,$p' $REPORT | tail -n +2 | wc -l`

  echo "There is $OUDATED_DEPENDENCIES_COUNT outdated dependencies!"
  printf '%b\n\n' "$(cat $REPORT)"

Now all you have to do is execute this script with single number param which will be maximum number of acceptable outdated libraries.



To find outdated libraries using maven you can use versions-maven-plugin. Add versions plugin to your plugins section:


Now you can display outdated packages using mvn versions:display-dependency-updates. If you want to run this check on CI tool then we need to analyze versions output. Luckily we don’t have to analyze all the stuff that maven produces. We can pass additional property value and save the report to file. Just run

mvn versions:display-dependency-updates -Dversions.outputFile=target/outdated.txt

and versions plugin will plain text file with info what should be updated:

The following dependencies in Dependencies have newer versions:
  junit:junit ............................................ 3.8.1 -> 4.12
  org.apache.commons:commons-lang3 .......................... 3.4 -> 3.5

The output file can be easily verified if there are outdated libraries.

I like to use console for my day to day work, but I hate typing long commands so let’s wrap it up into a single reusable script which can be used on CI:



mkdir -p target

./mvnw -q versions:display-dependency-updates -Dversions.outputFile="$OUTPUT" 

OUTDATED_LIBRARIES=`grep . "$OUTPUT" | tail -n +2 | wc -l`

  echo "There is $OUTDATED_LIBRARIES outdated libraries!\n"
  printf '%b\n\n' "$(cat target/outdated.txt)"

As in previous examples to run script you must provide single argument which will be maximum number of acceptable outdated libraries

When using maven and versions plugin there are also additional targets you can execute (including site report generation and finding outdated plugins). Checkout documentation for more details.


30 Mar 2017 #mvn #gradle #npm