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author | Robert Hensing <roberth@users.noreply.github.com> | 2020-11-05 10:40:39 +0100 |
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committer | GitHub <noreply@github.com> | 2020-11-05 10:40:39 +0100 |
commit | d24360033de665a6d83fa8298ca009eae6e674e3 (patch) | |
tree | e232186f15c3b9da7a5ea369c3c114595a250dab /doc | |
parent | 7cd06d3ceba5fe30e14075bfeb5bda5fa5394fda (diff) | |
parent | d4efa08b536d7dc500c2df45d7efa8087ca19557 (diff) |
Merge pull request #98383 from raboof/document-jre
openjdk: add derivation to generate bespoke minimal JRE's
Diffstat (limited to 'doc')
-rw-r--r-- | doc/languages-frameworks/java.xml | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/doc/languages-frameworks/java.xml b/doc/languages-frameworks/java.xml index bf0fc4883922..881d492b5bff 100644 --- a/doc/languages-frameworks/java.xml +++ b/doc/languages-frameworks/java.xml @@ -32,7 +32,7 @@ nativeBuildInputs = [ jdk ]; </para> <para> - If your Java package provides a program, you need to generate a wrapper script to run it using the OpenJRE. You can use <literal>makeWrapper</literal> for this: + If your Java package provides a program, you need to generate a wrapper script to run it using a JRE. You can use <literal>makeWrapper</literal> for this: <programlisting> nativeBuildInputs = [ makeWrapper ]; @@ -43,7 +43,21 @@ installPhase = --add-flags "-cp $out/share/java/foo.jar org.foo.Main" ''; </programlisting> - Note the use of <literal>jre</literal>, which is the part of the OpenJDK package that contains the Java Runtime Environment. By using <literal>${jre}/bin/java</literal> instead of <literal>${jdk}/bin/java</literal>, you prevent your package from depending on the JDK at runtime. +Since the introduction of the Java Platform Module System in Java 9, Java distributions typically no longer ship with a general-purpose JRE: instead, they allow generating a JRE with only the modules required for your application(s). Because we can't predict what modules will be needed on a general-purpose system, the default <package>jre</package> package is the full JDK. When building a minimal system/image, you can override the <literal>modules</literal> parameter on <literal>jre_minimal</literal> to build a JRE with only the modules relevant for you: +<programlisting> +let + my_jre = pkgs.jre_minimal.override { + modules = [ + # The modules used by 'something' and 'other' combined: + "java.base" + "java.logging" + ]; + }; + something = (pkgs.something.override { jre = my_jre; }); + other = (pkgs.other.override { jre = my_jre; }); +in + ... +</programlisting> </para> <para> |