blog: JDK21 early access builds (#2067)

* blog: JDK21 early access builds

Signed-off-by: Stewart X Addison <[email protected]>

---------

Signed-off-by: Stewart X Addison <[email protected]>
Co-authored-by: George Adams <[email protected]>

content/blog/early-access-builds/index.md

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+---
+title: Early access builds for JDK21
+date: "2023-08-14T14:00:00+00:00"
+author: sxa
+description: Adoptium are publishing early access "tagged" builds instead of nightlies for JDK21
+tags:
+  - temurin
+---
+In addition to the generally available release builds of all currently supported
+versions of openjdk (Currently 8, 11, 17 and 20) Temurin also publishes "nightly"
+development builds of all of those streams as well as the upcoming release (JDK21
+at the moment) as "nightly" or "early access" builds. You can get these from
+[the nightly downloads page](https://adoptium.net/temurin/nightly/?version=21)
+or from the API. Note that while these are
+not intended for production use they can be used to test a build containing any
+new fixes which have been put into openjdk along with any new features that
+will be coming in the next release.
+
+## Early access (ea) tagged builds of JDK21
+
+We have recently changed the way we do the regular nightly builds of JDK21.
+Instead of producing regular builds of the latest development code, we are
+building explicitly from the early access tags when they come out.  This is
+consistent with what OpenJDK does with the builds at
+https://jdk.java.net/21/ but on a wider range of platforms.  Similar to the
+nightly builds mentioned in the introduction, these are not for production
+use but may be useful for testing new features as they go into the JDK21
+codebase.  By using the specific early access tags you can also report
+issues upstream more easily by knowing exactly which tagged level you have
+discovered any problems with.
+
+You can download the latest ea build from the API by retrieving this (replace
+linux and x64 with the platform you are interested in:
+
+```text
+https://api.adoptium.net/v3/binary/latest/21/ea/linux/x64/jdk/hotspot/normal/adoptium
+```
+
+If you want to download a specific EA build instead of the latest, you can
+do so using a URL such as:
+
+```text
+https://api.adoptium.net/v3/binary/version/jdk-21+32-ea-beta/linux/aarch64/jdk/hotspot/normal/adoptium
+```
+
+The output from java -version for these builds will look like this (but it
+may change in the future) The `-ea` indicates that it is build from the
+early access tag in GitHub:
+
+```output
+openjdk version "21-beta" 2023-09-19
+OpenJDK Runtime Environment Temurin-21+34-202308031254 (build 21-beta+34-ea)
+OpenJDK 64-Bit Server VM Temurin-21+34-202308031254 (build 21-beta+34-ea, mixed mode, sharing)
+```
+
+## Using the ea builds with GitHub actions
+
+If you want to pull a Temurin JDK21 ea build in a GitHub action, you can use
+the following:
+
+```yaml
+     - uses: actions/setup-java@v3
+        with:
+          java-version: 21-ea
+          distribution: temurin
+```
+
+## Will you be doing this with earlier releases?
+
+We are looking at whether it makes sense to build ea levels instead of
+regular nightly head builds of the other supported codebases. If you have a
+view on whether that would be useful please let us know by commenting in
+[this issue](https://github.com/adoptium/temurin-build/issues/3450).