add integration files for circle ci

This is based on the circle ci integration we have
for citus, albeit highly simplified.

.circleci/build.sh

@@ -0,0 +1,16 @@
+#!/bin/bash
+
+set -euxo pipefail
+IFS=$'\n\t'
+
+status=0
+
+basedir="$(pwd)"
+installdir="${basedir}/install-${PG_MAJOR}"
+
+make install DESTDIR="${installdir}"
+pushd "${installdir}"
+find . -type f -print > "${basedir}/files.lst"
+cat "${basedir}/files.lst"
+tar cvf "${basedir}/install-${PG_MAJOR}.tar" $(cat "${basedir}/files.lst")
+popd

.circleci/config.yml

@@ -0,0 +1,101 @@
+version: 2.1
+orbs:
+  codecov: codecov/codecov@1.1.1
+
+jobs:
+  check-style:
+    docker:
+      - image: 'citus/stylechecker:latest'
+    steps:
+      - checkout
+      - run:
+          name: 'Check Style'
+          command: |
+            citus_indent --check
+      - run:
+          name: 'Check if whitespace fixing changed anything, install editorconfig if it did'
+          command: |
+            git diff --exit-code
+
+  build-11:
+    docker:
+      - image: 'citus/extbuilder:11.9'
+    steps:
+      - checkout
+      - run:
+          name: 'Configure, Build, and Install'
+          command: |
+            PG_MAJOR=11 .circleci/build.sh
+      - persist_to_workspace:
+          root: .
+          paths:
+            - install-11.tar
+
+  build-12:
+    docker:
+      - image: 'citus/extbuilder:12.4'
+    steps:
+      - checkout
+      - run:
+          name: 'Configure, Build, and Install'
+          command: |
+            PG_MAJOR=12 .circleci/build.sh
+      - persist_to_workspace:
+          root: .
+          paths:
+            - install-12.tar
+
+  test-11_checkinstall:
+    docker:
+      - image: 'citus/exttester:11.9'
+    working_directory: /home/circleci/project
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - run:
+          name: 'Prepare Container & Install Extension'
+          command: |
+            chown -R circleci:circleci /home/circleci
+            tar xfv "${CIRCLE_WORKING_DIRECTORY}/install-${PG_MAJOR}.tar" --directory /
+      - run:
+          name: 'Run Test'
+          command: |
+            gosu circleci .circleci/run_test.sh installcheck
+      - codecov/upload:
+          flags: 'test_11,installcheck'
+
+  test-12_checkinstall:
+    docker:
+      - image: 'citus/exttester:12.4'
+    working_directory: /home/circleci/project
+    steps:
+      - checkout
+      - attach_workspace:
+          at: .
+      - run:
+          name: 'Prepare Container & Install Extension'
+          command: |
+            chown -R circleci:circleci /home/circleci
+            tar xfv "${CIRCLE_WORKING_DIRECTORY}/install-${PG_MAJOR}.tar" --directory /
+      - run:
+          name: 'Run Test'
+          command: |
+            gosu circleci .circleci/run_test.sh installcheck
+      - codecov/upload:
+          flags: 'test_12,installcheck'
+
+workflows:
+  version: 2
+  build_and_test:
+    jobs:
+
+      - check-style
+
+      - build-11
+      - build-12
+
+      - test-11_checkinstall:
+          requires: [build-11]
+      - test-12_checkinstall:
+          requires: [build-12]

.circleci/run_test.sh

@@ -0,0 +1,27 @@
+#!/bin/bash
+
+set -euxo pipefail
+IFS=$'\n\t'
+
+status=0
+
+export PGPORT=${PGPORT:-55432}
+
+function cleanup {
+  pg_ctl -D /tmp/postgres stop
+  rm -rf /tmp/postgres
+}
+trap cleanup EXIT
+
+rm -rf /tmp/postgres
+initdb -E unicode /tmp/postgres
+echo "shared_preload_libraries = 'cstore_fdw'" >> /tmp/postgres/postgresql.conf
+pg_ctl -D /tmp/postgres -o "-p ${PGPORT}" -l /tmp/postgres_logfile start || status=$?
+if [ -z $status ]; then cat /tmp/postgres_logfile; fi
+
+make "${@}" || status=$?
+diffs="regression.diffs"
+
+if test -f "${diffs}"; then cat "${diffs}"; fi
+
+exit $status

.gitignore

@@ -60,3 +60,8 @@
 .vscode
 
 *.pb-c.*
+
+# ignore files that could be created by circleci automation
+files.lst
+install-*.tar
+install-*/