Sonatype NEXUS 2 has a rest API :-) but NEXUS 3 has none/not ready, the following simulate curl/wget call

readme.md

Fetching artifact programmatically through REST/API fro Nexus2/3

Nexus 2.x had a REST API to download artifacts like below based on some Maven GAV co-ordinates but this no longer works for Nexus 3.x

Nexus 2.x

Nexus 2.x had a REST API to download artifacts based on some Maven GAV co-ordinates

wget "http://local:8081/service/local/artifact/maven/redirect?g=com.mycompany&a=my-app&v=LATEST" --content-disposition

or

curl --insecure "https://local:8081/service/local/artifact/maven/content?r=public&g=log4j&a=log4j&v=1.2.17&p=jar&c=" > log4j.jar

Nexus 3.x

Nexus 3.x has no REST API to fetch artifacts.

Solution 1

If you can tolerate to have maven in path properly configured on system, You can replace all your REST call with a one line maven call

mvn org.apache.maven.plugins:maven-dependency-plugin:3.0.1:copy -Dartifact=log4j:log4j:1.2.17:jar -DoutputDirectory=./

This support ONLY getting releases! snapshot with unique ID are not supported

Solution 2

Here is my pure bash implementation of wget that can fetch release and discover latest version of SNAPSHOT

#!/bin/sh

repo="https://nexus.url.com"
groupId=$1
artifactId=$2
version=$3

# optional
classifier=$4
type=$5

if [[ $type == "" ]]; then
  type="jar"
fi
if [[ $classifier != "" ]]; then
  classifier="-${classifier}"
fi

groupIdUrl="${groupId//.//}"
filename="${artifactId}-${version}${classifier}.${type}"

if [[ ${version} == *"SNAPSHOT"* ]]; then repo_type="snapshots"; else repo_type="releases"; fi

if [[ $repo_type == "releases" ]]
 then
   wget --no-check-certificate "${repo}/repository/releases/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${version}${classifier}.${type}" -O ${filename} -k
 else
   versionTimestamped=$(wget -q -O- --no-check-certificate "${repo}/repository/snapshots/${groupIdUrl}/${artifactId}/${version}/maven-metadata.xml" | grep -m 1 \<value\> | sed -e 's/<value>\(.*\)<\/value>/\1/' | sed -e 's/ //g')

   wget --no-check-certificate "${repo}/repository/snapshots/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${versionTimestamped}${classifier}.${type}" -O ${filename}
 fi
 
´´´

usage
 script.sh groupid artifactid version classifier type
 ex:
 script.sh log4j log4j 4.2.18 sources zip 
 script.sh log4j log4j 4.2.19  -> get jar as default
 script.sh log4j log4j 4.2.19-SNAPSHOT  -> get jar as default

This script also resolves LATEST.

#!/bin/bash                                                                                                                                                                                                      
                                                                                                                                                                                                                 
# http://redsymbol.net/articles/unofficial-bash-strict-mode/                                                                                                                                                     
set -euo pipefail                                                                                                                                                                                                
IFS=$'\n\t'                                                                                                                                                                                                      
                                                                                                                                                                                                                 
groupId=$1                                                                                                                                                                                                       
artifactId=$2                                                                                                                                                                                                    
version=$3                                                                                                                                                                                                       
                                                                                                                                                                                                                 
# optional                                                                                                                                                                                                       
classifier=${4:-}                                                                                                                                                                                                
type=${5:-jar}                                                                                                                                                                                                   
repo=${6:-snapshots}                                                                                                                                                                                             
                                                                                                                                                                                                                 
# Nexus 2                                                                                                                                                                                                        
#base="http://nexus.example.com/service/local/repositories/${repo}/content"                                                                                                                                                   
# Nexus 3                                                                                                                                                                                                        
base="http://nexus.example.com/repository/${repo}"                                                                                                                                                                            
                                                                                                                                                                                                                 
if [[ $classifier != "" ]]; then                                                                                                                                                                                 
  classifier="-${classifier}"                                                                                                                                                                                    
fi                                                                                                                                                                                                               
                                                                                                                                                                                                                 
groupIdUrl="${groupId//.//}"                                                                                                                                                                                     
filename="${artifactId}-${version}${classifier}.${type}"                                                                                                                                                         
                                                                                                                                                                                                                 
if [[ "${version}" == "LATEST" || "${version}" == *SNAPSHOT* ]] ; then                                                                                                                                           
  if [[ "${version}" == "LATEST" ]] ; then                                                                                                                                                                       
    version=$(xmllint --xpath "string(//latest)" <(curl -s "${base}/${groupIdUrl}/${artifactId}/maven-metadata.xml"))                                                                                            
  fi                                                                                                                                                                                                             
  timestamp=$(xmllint --xpath "string(//timestamp)" <(curl -s "${base}/${groupIdUrl}/${artifactId}/${version}/maven-metadata.xml"))                                                                              
  buildnumber=$(xmllint --xpath "string(//buildNumber)" <(curl -s "${base}/${groupIdUrl}/${artifactId}/${version}/maven-metadata.xml"))                                                                          
  curl -s -o ${filename} "${base}/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${version%-SNAPSHOT}-${timestamp}-${buildnumber}${classifier}.${type}"                                                    
else                                                                                                                                                                                                             
  curl -s -o ${filename} "${base}/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${version}${classifier}.${type}"                                                                                          
fi

I need to get the snapshot and this one worked for me:
mvn org.apache.maven.plugins:maven-dependency-plugin:3.0.1:copy -Dartifact=my.id:my-app:1-SNAPSHOT:war -DoutputDirectory=./

Thanks for these scripts, you've saved me hours !

I am using 3.0.0 the script does not work for me, do I need to upgrade to any specific version?

Thanks a lot script works for me, i did little changes to extend if version number is not provided then get latest version, also rather than taking build from repository i directly took both release and snapshot from maven-public group

#!/bin/sh

repo="https://nexus.local"
groupId=$1
artifactId=$2
version=$3

classifier=$4
type=$5

if [[ $type == "" ]]; then
type="jar"
fi
if [[ $classifier != "" ]]; then
classifier="-${classifier}"
fi
groupIdUrl="${groupId//.//}"
if [[ $version == "" ]]; then
version=$(wget -q -O- --no-check-certificate "${repo}/repository/maven-public/${groupIdUrl}/${artifactId}/maven-metadata.xml" | grep -m 1 <latest> | sed -e 's/(.*)</latest>/\1/' | sed -e 's/ //g')
fi

filename="${artifactId}-${version}${classifier}.${type}"

if [[ ${version} == "SNAPSHOT" ]]; then repo_type="snapshots"; else repo_type="releases"; fi

if [[ $repo_type == "releases" ]]
then
wget --no-check-certificate "${repo}/repository/maven-public/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${version}${classifier}.${type}" -O ${filename} -k
else
versionTimestamped=$(wget -q -O- --no-check-certificate "${repo}/repository/maven-public/${groupIdUrl}/${artifactId}/${version}/maven-metadata.xml" | grep -m 1 <value> | sed -e 's/(.*)</value>/\1/' | sed -e 's/ //g')

wget --no-check-certificate "${repo}/repository/maven-public/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${versionTimestamped}${classifier}.${type}" -O ${filename}
fi

Adapted code of @rbjorklin to work with sh, those parentheses near xmllint are not so compatible across sh.
Code is the same. Great work extracting the build numbers.

#!/bin/sh

# http://redsymbol.net/articles/unofficial-bash-strict-mode/                                                                                                                                                     
set -euo pipefail                                                                                                                                                                                                
IFS=$'\n\t'

groupId=$1
artifactId=$2
version=$3

# optional                                                                                                                                                                                                       
classifier=${4:-}                                                                                                                                                                                                
type=${5:-war}                                                                                                                                                                                                   
repo=${6:-snapshots}                                                                                                                                                                                             
                                                                                                                                                                                                                 
# Nexus 2                                                                                                                                                                                                        
#base="http://nexus.example.com/service/local/repositories/${repo}/content"                                                                                                                                                   
# Nexus 3                                                                                                                                                                                                        
base="http://nexus.example.com/repository/${repo}"                                                                                                                                                                         
                                                                                                                                                                                                                 
if [[ $classifier != "" ]]; then                                                                                                                                                                                 
  classifier="-${classifier}"                                                                                                                                                                                    
fi                                                                                                                                                                                                               
                                                                                                                                                                                                                 
groupIdUrl="${groupId//.//}"                                                                                                                                                                                     
filename="${artifactId}-${version}${classifier}.${type}"                                                                                                                                                         
                                                                                                                                                                                                                 
if [[ "${version}" == "LATEST" || "${version}" == *SNAPSHOT* ]] ; then                                                                                                                                           
  if [[ "${version}" == "LATEST" ]] ; then                                                                                                                                                                       
    version=$(xmllint --xpath "string(//latest)" <(curl -s "${base}/${groupIdUrl}/${artifactId}/maven-metadata.xml"))                                                                                            
  fi                                                                                                                                                                                                             
  timestamp=`curl -s "${base}/${groupIdUrl}/${artifactId}/${version}/maven-metadata.xml" | xmllint --xpath "string(//timestamp)" -`
  buildnumber=`curl -s "${base}/${groupIdUrl}/${artifactId}/${version}/maven-metadata.xml" | xmllint --xpath "string(//buildNumber)" -`
  curl -s -o ${filename} "${base}/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${version%-SNAPSHOT}-${timestamp}-${buildnumber}${classifier}.${type}"                                                    
else                                                                                                                                                                                                             
  curl -s -o ${filename} "${base}/${groupIdUrl}/${artifactId}/${version}/${artifactId}-${version}${classifier}.${type}"                                                                                          
fi

Thanks @rzr999. saved me !!

Does anyone know if there’s a public Nexus Repository that I can try this code on without having to spin up my own Nexus instance?

According to docs starting from 3.16 there is new endpoint:
https://help.sonatype.com/repomanager3/rest-and-integration-api/search-api#SearchAPI-DownloadingtheLatestVersionofanAsset