Support JVM-Config and environment variables for proxy configuration

[mcandre]

Affected version

• v3 series

Bug description

Despite dozens of community discussions claiming otherwise on Reddit, Stack Overflow, old Apache bug trackers, and new GitHub Apache bug trackers, neither Maven nor Maven Wrapper support .mvn/jvm.config nor environment variables for simple proxy configuration.

None of the industry standard mechanisms available to Gradle, to other programming languages, to Ant, work in v3 Maven.

• Industry standard, cURL based environment variables: http_proxy, http_proxy, no_proxy
• UPPERCASE environment variables: HTTP_PROXY, HTTPS_PROXY, NO_PROXY
• Maven wrapper .mvn/jvm.config files
• Maven's environment variables: MAVEN_ARGS, MAVEN_OPTS
• JVM standard JAVA_OPTS environment variable

As a workaround, settings.xml can be hardcoded to apply a proxy configuration. But this makes it significantly harder to override partial Maven configurations, compared with environment variables.

[cstamas]

This is intentional, user must "tell" Maven Apache transport to observe these properties.

Have you tried the property aether.connector.http.useSystemProperties from documentation [1]? In that case properties are observed, as explained here [2].

[1] https://maven.apache.org/resolver-archives/resolver-1.9.24/configuration.html
[2] https://hc.apache.org/httpcomponents-client-4.5.x/current/httpclient/apidocs/org/apache/http/impl/client/HttpClientBuilder.html

[mcandre]

Computers exist to automate, not incur additional labor. The JVM already has fairly standard parameters to configure transport details. Other Java components already follow them. Maven is an outlier for requiring reminding. Maven is notorious for exactly this kind of boilerplate. If there's a question of backwards compatibility, announce the change ahead of time, and do so in a major version increment.

…

On Mon, Aug 11, 2025 at 9:23 AM, Tamas Cservenak ***@***.***(mailto:On Mon, Aug 11, 2025 at 9:23 AM, Tamas Cservenak <<a href=)> wrote: cstamas left a comment [(apache/maven#11011)](#11011 (comment)) This is intentional, user must "tell" Maven Apache transport to observe these properties. Have you tried the property aether.connector.http.useSystemProperties from documentation [1]? In that case properties are observed, as explained here [2]. [1] https://maven.apache.org/resolver-archives/resolver-1.9.24/configuration.html [2] https://hc.apache.org/httpcomponents-client-4.5.x/current/httpclient/apidocs/org/apache/http/impl/client/HttpClientBuilder.html — Reply to this email directly, [view it on GitHub](#11011 (comment)), or [unsubscribe](https://github.com/notifications/unsubscribe-auth/AAABJRE5BZYZKFCEWHQD5E33NCROZAVCNFSM6AAAAACCSAVWAGVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTCNZVGA3TSOJWGE). You are receiving this because you authored the thread.Message ID: ***@***.***>

[cstamas]

Terrible, indeed.

[gnodet]

Computers exist to automate, not incur additional labor.

The JVM already has fairly standard parameters to configure transport details. Other Java components already follow them. Maven is an outlier for requiring reminding.

Maven is notorious for exactly this kind of boilerplate.

If there's a question of backwards compatibility, announce the change ahead of time, and do so in a major version increment.
…

So it's just about adding aether.connector.http.useSystemProperties=true in your maven configuration file. Have you tried that ? Not that much boilerplate really.

[jgneff]

Have you tried the property aether.connector.http.useSystemProperties from documentation [1]?

Thank you, Tamás! That solved the problem I encountered building Maven 3.9.13 on the Ubuntu Launchpad build farm.

Although the Artifact Resolver documentation states, "This mode is not recommended," I have not found a way to make this work using the recommended way of configuring a proxy. See below for details.

Using System Properties - Works

The Launchpad build farm provides its proxy settings in the environment variables http_proxy and https_proxy. The most direct way to pass these settings to Maven is to parse their values and get them into the corresponding Java system properties:

# Gets the host and port from a proxy URL
#   $1 = the proxy URL, such as "http://10.10.10.1:8222/"
getproxy () {
    # Parses URL with Bash or Dash shell parameter expansion
    tail=${1#http*://}
    head=${tail%%/*}
    host=${head%:*}
    port=${head##*:}
}

# Sets Java networking properties when using a proxy server
proxies="-Daether.connector.http.useSystemProperties=true"
if [ -n "${http_proxy:-}" ]; then
    getproxy "$http_proxy"
    proxies="$proxies -Dhttp.proxyHost=$host -Dhttp.proxyPort=$port"
fi
if [ -n "${https_proxy:-}" ]; then
    getproxy "$https_proxy"
    proxies="$proxies -Dhttps.proxyHost=$host -Dhttps.proxyPort=$port"
fi

# Builds Maven
export MAVEN_HOME="$CRAFT_STAGE/apache-maven-3.9.12"
export MAVEN_OPTS="$proxies"
"$MAVEN_HOME/bin/mvn" --batch-mode --strict-checksums \
    --define distributionTargetDir="$CRAFT_PART_INSTALL/maven" \
    --quiet --show-version package

After adding the property aether.connector.http.useSystemProperties=true, the five HTTPS requests made by Maven during the build now go through the Launchpad proxy server, as required:

:: + MAVEN_OPTS='-Daether.connector.http.useSystemProperties=true -Dhttp.proxyHost=10.10.10.1 -Dhttp.proxyPort=8222 -Dhttps.proxyHost=10.10.10.1 -Dhttps.proxyPort=8222'
:: + /build/strictly-maven/stage/apache-maven-3.9.12/bin/mvn --batch-mode --strict-checksums --define distributionTargetDir=/build/strictly-maven/parts/mvn/install/maven --quiet --show-version package
:: Apache Maven 3.9.12 (848fbb4bf2d427b72bdb2471c22fced7ebd9a7a1)
:: Maven home: /build/strictly-maven/stage/apache-maven-3.9.12
:: Java version: 17.0.18, vendor: Ubuntu, runtime: /usr/lib/jvm/java-17-openjdk-amd64
:: Default locale: en, platform encoding: UTF-8
:: OS name: "linux", version: "6.8.0-101-generic", arch: "amd64", family: "unix"
:: + cp /build/strictly-maven/conf/settings-global.xml /build/strictly-maven/parts/mvn/install/maven/conf/settings.xml
[05/Mar/2026:17:26:33 +0000] "CONNECT repo.maven.apache.org:443 HTTP/1.1" 200 46893516 "-" "Apache-Maven/3.9.12 (Java 17.0.18; Linux 6.8.0-101-generic)"
[05/Mar/2026:17:26:33 +0000] "CONNECT repo.maven.apache.org:443 HTTP/1.1" 200 19725553 "-" "Apache-Maven/3.9.12 (Java 17.0.18; Linux 6.8.0-101-generic)"
[05/Mar/2026:17:26:33 +0000] "CONNECT repo.maven.apache.org:443 HTTP/1.1" 200 21162014 "-" "Apache-Maven/3.9.12 (Java 17.0.18; Linux 6.8.0-101-generic)"
[05/Mar/2026:17:26:33 +0000] "CONNECT repo.maven.apache.org:443 HTTP/1.1" 200 22801397 "-" "Apache-Maven/3.9.12 (Java 17.0.18; Linux 6.8.0-101-generic)"
[05/Mar/2026:17:26:33 +0000] "CONNECT repo.maven.apache.org:443 HTTP/1.1" 200 25469084 "-" "Apache-Maven/3.9.12 (Java 17.0.18; Linux 6.8.0-101-generic)"

Using settings.xml - Fails

I have not found a way to get the host and port of the proxy servers into the settings.xml file in a dynamic way that works. If I hard-code the values in the file, it works fine. But if I try to use Java system properties or Maven user properties in the file, they are not recognized.

I've tried setting an HTTP proxy and an HTTPS proxy, and I've tried using MAVEN_OPTS and MAVEN_ARGS, but nothing works.

Below is the shell script:

# Gets the host and port from a proxy URL
#   $1 = the proxy URL, such as "http://10.10.10.1:8222/"
getproxy () {
    # Parses URL with Bash or Dash shell parameter expansion
    tail=${1#http*://}
    head=${tail%%/*}
    host=${head%:*}
    port=${head##*:}
}

# Sets Java networking properties when using a proxy server
proxies="-Dproxy.active=false"
if [ -n "${https_proxy:-}" ]; then
    proxies="-Dproxy.active=true"
    getproxy "$https_proxy"
    proxies="$proxies -Dhttps.proxyHost=$host -Dhttps.proxyPort=$port"
fi

# Builds Maven
export MAVEN_HOME="$CRAFT_STAGE/apache-maven-3.9.12"
export MAVEN_OPTS="$proxies"
"$MAVEN_HOME/bin/mvn" --batch-mode --strict-checksums \
    --define distributionTargetDir="$CRAFT_PART_INSTALL/maven" \
    --quiet --settings "$CRAFT_PROJECT_DIR/conf/settings-build.xml" \
    --show-version package

And below is the settings.xml file I'm using:

<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.2.0 https://maven.apache.org/xsd/settings-1.2.0.xsd">
    <proxies>
        <proxy>
            <active>${proxy.active}</active>
            <protocol>https</protocol>
            <host>${https.proxyHost}</host>
            <port>${https.proxyPort}</port>
        </proxy>
    </proxies>
</settings>

Yet the build fails with an error indicating that it's not using the proxy servers:

:: + MAVEN_OPTS='-Dproxy.active=true -Dhttps.proxyHost=10.10.10.1 -Dhttps.proxyPort=8222'
:: + /build/snapcraft-strictly-maven-8fd0a4626b0abe4c1ea2dab99328bc4c/stage/apache-maven-3.9.12/bin/mvn --batch-mode --strict-checksums --define distributionTargetDir=/build/snapcraft-strictly-maven-8fd0a4626b0abe4c1ea2dab99328bc4c/parts/mvn/install/maven --quiet --settings /build/snapcraft-strictly-maven-8fd0a4626b0abe4c1ea2dab99328bc4c/conf/settings-build.xml --show-version package
:: Apache Maven 3.9.12 (848fbb4bf2d427b72bdb2471c22fced7ebd9a7a1)
:: Maven home: /build/snapcraft-strictly-maven-8fd0a4626b0abe4c1ea2dab99328bc4c/stage/apache-maven-3.9.12
:: Java version: 17.0.18, vendor: Ubuntu, runtime: /usr/lib/jvm/java-17-openjdk-amd64
:: Default locale: en, platform encoding: UTF-8
:: OS name: "linux", version: "6.8.0-101-generic", arch: "amd64", family: "unix"
:: [ERROR] [ERROR] Some problems were encountered while processing the POMs:
:: [FATAL] Non-resolvable parent POM for org.apache.maven:maven:3.9.13: The following artifacts could not be resolved: org.apache.maven:maven-parent:pom:47 (absent): Could not transfer artifact org.apache.maven:maven-parent:pom:47 from/to central (https://repo.maven.apache.org/maven2): repo.maven.apache.org: Name or service not known and 'parent.relativePath' points at no local POM @ line 23, column 11
::  @
:: [ERROR] The build could not read 1 project -> [Help 1]
:: [ERROR]
:: [ERROR]   The project org.apache.maven:maven:3.9.13 (/build/snapcraft-strictly-maven-8fd0a4626b0abe4c1ea2dab99328bc4c/parts/mvn/build/pom.xml) has 1 error
:: [ERROR]     Non-resolvable parent POM for org.apache.maven:maven:3.9.13: The following artifacts could not be resolved: org.apache.maven:maven-parent:pom:47 (absent): Could not transfer artifact org.apache.maven:maven-parent:pom:47 from/to central (https://repo.maven.apache.org/maven2): repo.maven.apache.org: Name or service not known and 'parent.relativePath' points at no local POM @ line 23, column 11: Unknown host repo.maven.apache.org: Name or service not known -> [Help 2]

Any idea what I'm doing wrong?

[cstamas]

wow, I think there is a nasty bug in processing of settings.xml
Just for experiment sake, can you replace <port>${https.proxyPort}</port> bit with <port>8222</port>?
Same for <active>${proxy.active}</active>, in fact, can you for experiment sake just replace (manually "interpolate") all the values?

[cstamas]

Wow, https://issues.apache.org/jira/browse/MNG-6401 and many others. In fact, interpolation of settings.xml does not work at all (as for example POM works). And seems this was always the case (affects whole 3.x line!).

[jgneff]

Just for experiment sake, can you replace <port>${https.proxyPort}</port> bit with <port>8222</port>? Same for <active>${proxy.active}</active>, in fact, can you for experiment sake just replace (manually "interpolate") all the values?

I tried hard-coding (manually "interpolating") the values in the file, and it worked fine.

So the general concept of using the settings.xml file for proxy configuration works. I was unable to find any way to substitute values for MAVEN_ARGS (Maven user properties) or MAVEN_OPTS (Java system properties) in the user settings file.

[cstamas]

Yes, it is the interpolation that is totally broken. Expressions like <port>${https.proxyPort}</port> and alike are totally broken, does not work 😞