Add ABI test against PG snapshot

This adds a test to check the ABI compatibility with PG snapshot.
Timescaledb is built against the mininum abi version of postgres
supported, for each major version of PG and tested against the latest
snapshot.

.github/workflows/snapshot-abi.yaml

@@ -0,0 +1,173 @@
+# Test ABI versions against snapshot
+#
+#
+
+name: ABI Test Against Snapshot
+"on":
+  schedule:
+    # run daily 20:00 on main branch
+    - cron: '0 20 * * *'
+  push:
+    branches:
+      - prerelease_test
+      - trigger/snapshot-abi
+  pull_request:
+    paths: .github/workflows/snapshot-abi.yaml
+jobs:
+  config:
+    runs-on: ubuntu-latest
+    outputs:
+      pg14_abi_min: ${{ steps.config.outputs.pg14_abi_min }}
+      pg15_abi_min: ${{ steps.config.outputs.pg15_abi_min }}
+      pg16_abi_min: ${{ steps.config.outputs.pg16_abi_min }}
+      pg17_abi_min: ${{ steps.config.outputs.pg17_abi_min }}
+
+    steps:
+    - name: Checkout source code
+      uses: actions/checkout@v4
+    - name: Read configuration
+      id: config
+      run: python .github/gh_config_reader.py
+
+  abi_snapshot_test:
+    name: ABI Snapshot Test PG${{ matrix.pg }}
+    runs-on: ubuntu-latest
+    needs: config
+
+    env:
+      PG_SRC_DIR: pgbuild
+      PG_INSTALL_DIR: postgresql
+      PG_EXTENSIONS: postgres_fdw test_decoding pageinspect pgstattuple
+
+    strategy:
+      fail-fast: false
+      matrix:
+        pg: [ 14, 15, 16, 17 ]
+        include:
+          - pg: 14
+            abi_min: ${{ fromJson(needs.config.outputs.pg14_abi_min) }}
+          - pg: 15
+            abi_min: ${{ fromJson(needs.config.outputs.pg15_abi_min) }}
+          - pg: 16
+            abi_min: ${{ fromJson(needs.config.outputs.pg16_abi_min) }}
+          - pg: 17
+            abi_min: ${{ fromJson(needs.config.outputs.pg17_abi_min) }}
+
+    steps:
+
+    - name: Install Linux Dependencies
+      run: |
+        # Don't add ddebs here because the ddebs mirror is always 503 Service Unavailable.
+        # If needed, install them before opening the core dump.
+        sudo apt-get update
+        sudo apt-get install flex bison lcov systemd-coredump gdb libipc-run-perl \
+          libtest-most-perl pkgconf icu-devtools clang-14 llvm-14 llvm-14-dev llvm-14-tools cmake
+
+    - name: Checkout TimescaleDB
+      uses: actions/checkout@v4
+
+    - name: Download Postgres ${{ matrix.pg }}
+      run: |
+        wget -q -O postgresql.tar.bz2 \
+          https://ftp.postgresql.org/pub/source/v${{ matrix.abi_min }}/postgresql-${{ matrix.abi_min }}.tar.bz2
+        mkdir -p ~/$PG_SRC_DIR
+        tar --extract --file postgresql.tar.bz2 --directory ~/$PG_SRC_DIR --strip-components 1
+        cd ~/$PG_SRC_DIR
+        ./configure --prefix=$HOME/$PG_INSTALL_DIR --with-openssl \
+          --without-readline --without-zlib --without-libxml --without-llvm
+        make -j $(nproc)
+        for ext in $PG_EXTENSIONS; do
+          make -j $(nproc) -C contrib/${ext}
+        done
+
+    - name: Install postgresql ${{ matrix.pg }}
+      run: |
+        cd ~/$PG_SRC_DIR
+        make install
+        for ext in $PG_EXTENSIONS; do
+          make -C contrib/${ext} install
+        done
+        echo "$HOME/$PG_INSTALL_DIR/bin" >> "${GITHUB_PATH}"
+
+    - name: Build TimescaleDB
+      run: |
+        ./bootstrap -DCMAKE_BUILD_TYPE=Debug \
+          -DPG_SOURCE_DIR=~/$PG_SRC_DIR -DPG_PATH=~/$PG_INSTALL_DIR \
+          -DWARNINGS_AS_ERRORS=ON -DREQUIRE_ALL_TESTS=ON \
+          -DTEST_PG_LOG_DIRECTORY="$(readlink -f .)"
+        make -j $(nproc) -C build
+        make -C build install
+        mkdir -p build/install_ext build/install_lib
+        cp `pg_config --sharedir`/extension/timescaledb*.{control,sql} build/install_ext
+        cp `pg_config --pkglibdir`/timescaledb*.so build/install_lib
+
+    - name: Download Postgres ${{ matrix.pg }}-snapshot
+      run: |
+        wget -q -O postgresql.tar.bz2 \
+          https://ftp.postgresql.org/pub/snapshot/${{ matrix.pg }}/postgresql-${{ matrix.pg }}-snapshot.tar.bz2
+        mkdir -p ~/$PG_SRC_DIR-snapshot
+        tar --extract --file postgresql.tar.bz2 --directory ~/$PG_SRC_DIR-snapshot --strip-components 1
+        cd ~/$PG_SRC_DIR-snapshot
+        ./configure --prefix=$HOME/$PG_INSTALL_DIR-snapshot --with-openssl \
+          --without-readline --without-zlib --without-libxml --without-llvm
+        make -j $(nproc)
+        for ext in $PG_EXTENSIONS; do
+          make -j $(nproc) -C contrib/${ext}
+        done
+
+    - name: Install PostgreSQL ${{ matrix.pg }}-snapshot
+      run: |
+        cd ~/$PG_SRC_DIR-snapshot
+        make install
+        for ext in $PG_EXTENSIONS; do
+          make -C contrib/${ext} install
+        done
+        echo "$HOME/$PG_INSTALL_DIR-snapshot/bin" >> "${GITHUB_PATH}"
+
+    - name: Copy extension files to postgresql ${{ matrix.pg }}-snapshot
+      run: |
+        BUILD_DIR=build_snapshot ./bootstrap -DCMAKE_BUILD_TYPE=Debug \
+          -DPG_SOURCE_DIR=~/$PG_SRC_DIR-snapshot -DPG_PATH=~/$PG_INSTALL_DIR-snapshot \
+          -DWARNINGS_AS_ERRORS=ON -DREQUIRE_ALL_TESTS=ON \
+          -DTEST_PG_LOG_DIRECTORY="$(readlink -f .)"
+        cp build/install_ext/* `pg_config --sharedir`/extension/
+        cp build/install_lib/* `pg_config --pkglibdir`
+
+    - name: make regresscheck
+      id: regresscheck
+      run: |
+          set -o pipefail
+          make -k -C build_snapshot installcheck | tee installcheck.log
+
+    - name: Show regression diffs
+      if: always()
+      id: collectlogs
+      run: |
+        find . -name regression.diffs -exec cat {} + > regression.log
+
+        if [[ "${{ runner.os }}" == "Linux" ]] ; then
+          # wait in case there are in-progress coredumps
+          sleep 10
+          if coredumpctl -q list >/dev/null; then echo "coredumps=true" >>$GITHUB_OUTPUT; fi
+          # print OOM killer information
+          sudo journalctl --system -q --facility=kern --grep "Killed process" || true
+        elif [[ "${{ runner.os }}" == "macOS" ]] ; then
+           if [ $(find /cores -type f | wc -l) -gt 0 ]; then echo "coredumps=true" >>$GITHUB_OUTPUT; fi
+        fi
+        if [[ -s regression.log ]]; then echo "regression_diff=true" >>$GITHUB_OUTPUT; fi
+        grep -e 'FAILED' -e 'failed (ignored)' -e 'not ok' installcheck.log || true
+        cat regression.log
+
+    - name: Save regression diffs
+      if: always() && steps.collectlogs.outputs.regression_diff == 'true'
+      uses: actions/upload-artifact@v4
+      with:
+        name: Regression diff Snapshot ABI Breakage PG${{ matrix.pg }}
+        path: regression.log
+
+    - name: Save postmaster.log
+      if: always()
+      uses: actions/upload-artifact@v4
+      with:
+        name: PostgreSQL log Snapshot ABI Breakage PG${{ matrix.pg }}
+        path: postmaster.log