Add support for CircleCI integration builds

* Adding circleci support

* Trying to prevent sigkills according to https://discuss.circleci.com/t/builds-getting-killed-with-vague-message-received-signal-killed/10214/12

* Remove formatting, manage memory

* Max memory take 2

* Trying to build everything in one machine and one shot

* Adding echoes and fixing dir names

* See if parallelized builds work fine and fix geowebcache main pom location

* Trying to tighten memory a bit more while preserving parallel builds

* Back to sequential build

* Attempt to split into smaller commands and run down to GeoServer

* Some issues with directories, seem they are intepreted as relative, attempt to fix #1

* Some issues with directories, seem they are intepreted as relative, attempt to fix #2

* Some issues with directories, seem they are intepreted as relative, attempt to fix #3

* Don't update snapshots, trying to use less memory in GS build

* Don't update snapshots, trying to use less memory in GT build

* More memory work and starting to add repository caching

* Fixing indentation

* More caching fixes

* Ok, trying to get offline costs too much in terms of downloads

* One more attempt at getting a GS build that does not fail

* Temporarily add early cache saving to have something for the next build (speed up trial and error roundtrip)

* Damn you yaml

* Switching all builds to batch mode

* Cache was saved once, good enough, removing

* Community modules have been compiled, without tests, in the first command, the third is redundant

* Trying harder to release memory to the OS

* Breaking install into two lines, it keeps on failing due to lack of memory...

* Trying to centralize JVM configurations

* Yet another attempt to control memory usage

* war assembly failed in GWC due to memory, trying to give a bit more

* Fixing typo

* One more push on memory

* Circle CI limits by the minute, try to reduce build time as much as possible

Author: aaime

.circleci/config.yml

@@ -0,0 +1,66 @@
+version: 2 
+jobs: 
+  build: 
+    docker: 
+      - image: circleci/openjdk:8u212-jdk-stretch
+        command: ["/bin/bash"]
+    steps: 
+      - run:
+          name: Checkout GeoTools, GeoWebCache and GeoServer
+          command: |
+            echo "Preparing git ssh checkouts"
+            mkdir ~/.ssh/ && echo -e "Host github.com\n\tStrictHostKeyChecking no\n" > ~/.ssh/config
+            echo "Checking out GeoTools"
+            mkdir geotools
+            git clone git@github.com:geotools/geotools.git geotools
+            echo "Checking out GeoWebCache"
+            mkdir geowebcache
+            git clone git@github.com:GeoWebCache/geowebcache.git geowebcache
+            echo "Checking out GeoServer"
+            mkdir geoserver
+            git clone git@github.com:geoserver/geoserver.git geoserver
+
+      - run:
+          name: Generate cache key
+          command: |
+            find geotools geowebcache geoserver -name "pom.xml" | sort | xargs md5sum > /tmp/checksum.txt
+            cat /tmp/checksum.txt
+           
+      - restore_cache:
+          key: gt_gwc_gs-{{ checksum "/tmp/checksum.txt" }}
+
+      - run:
+          name: Build GeoTools (no tests, prepare fresh artifacts)
+          command: |
+            export TEST_OPTS="-XX:+UseStringDeduplication -XX:+UseG1GC -XX:MaxHeapFreeRatio=30 -XX:MinHeapFreeRatio=10"
+            export MAVEN_OPTS="-Xmx256m $TEST_OPTS"
+            mvn -B -f geotools/pom.xml install -Dall -Dfmt.skip=true -DskipTests
+
+      - run:
+          name: Build GeoWebCache with tests
+          command: |
+            export TEST_OPTS="-XX:+UseStringDeduplication -XX:+UseG1GC -XX:MaxHeapFreeRatio=30 -XX:MinHeapFreeRatio=10"
+            export MAVEN_OPTS="-Xmx512m $TEST_OPTS"
+            mvn -B -f geowebcache/geowebcache/pom.xml install -nsu -Dfmt.skip=true -DskipTests
+            mvn -B -f geowebcache/geowebcache/pom.xml test -nsu -T3 -Dfmt.skip=true
+
+      - run:
+          name: Build GeoServer with tests (and community modules without)
+          command: |
+            export TEST_OPTS="-XX:+UseStringDeduplication -XX:+UseG1GC -XX:MaxHeapFreeRatio=30 -XX:MinHeapFreeRatio=10"
+            export MAVEN_OPTS="-Xmx256m $TEST_OPTS"
+            mvn -B -f geoserver/src/pom.xml install -nsu -Prelease -Dfmt.skip=true -DskipTests
+            mvn -B -f geoserver/src/community/pom.xml install -nsu -DcommunityRelease -Dfmt.skip=true -DskipTests
+            mvn -B -f geoserver/src/pom.xml test -T3 -nsu -Dtest.maxHeapSize=512m -Djvm.opts="$TEST_OPTS" -Prelease -Dfmt.skip=true
+
+      - run:
+          name: Cleanup repository (remove snapshots)
+          command: |
+            rm -rf ~/.m2/repository/org/geotools
+            rm -rf ~/.m2/repository/org/geowebcache
+            rm -rf ~/.m2/repository/org/geoserver
+
+      - save_cache:
+          key: gt_gwc_gs-{{ checksum "/tmp/checksum.txt" }}
+          paths:
+            - ~/.m2/repository