diff --git a/.github/workflows/gcc.yml b/.github/workflows/gcc.yml
new file mode 100644
index 0000000000..6a5fce0ce7
--- /dev/null
+++ b/.github/workflows/gcc.yml
@@ -0,0 +1,95 @@
+name: GCC Linux Build
+on: [push, pull_request]
+
+# Use custom shell with -l so .bash_profile is sourced
+# without having to do it in manually every step
+defaults:
+  run:
+    shell: bash -leo pipefail {0}
+
+env:
+  cache_key: gcc3  # The number (#) following the cache_key "gcc" is to flush Action cache.
+  CC: gcc-10
+  FC: gfortran-10
+  CXX: g++-10
+
+# A note on flushing Action cache and relevance to "cache_key" above.
+# There is no way to flush the Action cache, and hence a number (#) is appended
+# to the "cache_key" (gcc).
+# If the dependencies change, increment this number and a new cache will be
+# generated by the dependency build step "setup"
+# There is a Github issue to force clear the cache.
+# See discussion on:
+# https://stackoverflow.com/questions/63521430/clear-cache-in-github-actions
+
+# The jobs are split into:
+# 1. a dependency build step (setup), and
+# 2. a GSI build step (build)
+# The setup is run once and the environment is cached,
+# so each build of GSI can reuse the cached dependencies to save time (and compute).
+
+jobs:
+  setup:
+    runs-on: ubuntu-latest
+
+    steps:
+      # Cache spack, compiler and dependencies
+      - name: cache-env
+        id: cache-env
+        uses: actions/cache@v2
+        with:
+          path: |
+            spack
+            ~/.spack
+          key: spack-${{ runner.os }}-${{ env.cache_key }}
+
+      - name: checkout-gsi  # This is for getting spack.yaml
+        if: steps.cache-env.outputs.cache-hit != 'true'
+        uses: actions/checkout@v2
+        with:
+            path: GSI
+
+      # Install dependencies using Spack
+      - name: install-dependencies-with-spack
+        if: steps.cache-env.outputs.cache-hit != 'true'
+        run: |
+          git clone -c feature.manyFiles=true https://github.com/NOAA-EMC/spack.git
+          source spack/share/spack/setup-env.sh
+          spack env create gsi-env GSI/ci/spack.yaml
+          spack env activate gsi-env
+          spack compiler find
+          spack external find
+          spack add mpich@3.4.2
+          spack concretize
+          spack install --dirty -v
+
+  build:
+    needs: setup
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: checkout-gsi
+        uses: actions/checkout@v2
+        with:
+            path: GSI
+
+      - name: cache-env
+        id: cache-env
+        uses: actions/cache@v2
+        with:
+          path: |
+            spack
+            ~/.spack
+          key: spack-${{ runner.os }}-${{ env.cache_key }}
+
+      - name: build-gsi
+        run: |
+          source spack/share/spack/setup-env.sh
+          spack env activate gsi-env
+          export CC=mpicc
+          export FC=mpif90
+          cd GSI
+          mkdir -p build && cd build
+          cmake -DCMAKE_INSTALL_PREFIX=../install -DGSI_MODE=Regional -DENKF_MODE=GFS -DBUILD_UTIL_ALL=ON -DBUILD_REG_TESTING=OFF -DBUILD_NCDIAG=OFF ..
+          make -j2 VERBOSE=1
+          make install
diff --git a/.github/workflows/intel.yml b/.github/workflows/intel.yml
new file mode 100644
index 0000000000..91bec976be
--- /dev/null
+++ b/.github/workflows/intel.yml
@@ -0,0 +1,114 @@
+name: Intel Linux Build
+on: [push, pull_request]
+
+# Use custom shell with -l so .bash_profile is sourced which loads intel/oneapi/setvars.sh
+# without having to do it in manually every step
+defaults:
+  run:
+    shell: bash -leo pipefail {0}
+
+# Set I_MPI_CC/F90 so Intel MPI wrapper uses icc/ifort instead of gcc/gfortran
+env:
+  cache_key: intel3  # The number (#) following the cache_key "intel" is to flush Action cache.
+  CC: icc
+  FC: ifort
+  CXX: icpc
+  I_MPI_CC: icc
+  I_MPI_F90: ifort
+
+# A note on flushing Action cache and relevance to "cache_key" above.
+# There is no way to flush the Action cache, and hence a number (#) is appended
+# to the "cache_key" (intel).
+# If the dependencies change, increment this number and a new cache will be
+# generated by the dependency build step "setup"
+# There is a Github issue to force clear the cache.
+# See discussion on:
+# https://stackoverflow.com/questions/63521430/clear-cache-in-github-actions
+
+# The jobs are split into:
+# 1. a dependency build step (setup), and
+# 2. a GSI build step (build)
+# The setup is run once and the environment is cached,
+# so each build of GSI can reuse the cached dependencies to save time (and compute).
+
+jobs:
+  setup:
+    runs-on: ubuntu-latest
+
+    steps:
+      # Cache spack, compiler and dependencies
+      - name: cache-env
+        id: cache-env
+        uses: actions/cache@v2
+        with:
+          path: |
+            spack
+            ~/.spack
+            /opt/intel
+          key: spack-${{ runner.os }}-${{ env.cache_key }}
+
+      - name: install-intel-compilers
+        if: steps.cache-env.outputs.cache-hit != 'true'
+        run: |
+          wget https://apt.repos.intel.com/intel-gpg-keys/GPG-PUB-KEY-INTEL-SW-PRODUCTS.PUB
+          sudo apt-key add GPG-PUB-KEY-INTEL-SW-PRODUCTS.PUB
+          echo "deb https://apt.repos.intel.com/oneapi all main" | sudo tee /etc/apt/sources.list.d/oneAPI.list
+          sudo apt-get update
+          sudo apt-get install intel-oneapi-dev-utilities intel-oneapi-mpi-devel intel-oneapi-openmp intel-oneapi-compiler-fortran intel-oneapi-compiler-dpcpp-cpp-and-cpp-classic
+          echo "source /opt/intel/oneapi/setvars.sh" >> ~/.bash_profile
+
+      - name: checkout-gsi  # This is for getting spack.yaml
+        if: steps.cache-env.outputs.cache-hit != 'true'
+        uses: actions/checkout@v2
+        with:
+            path: GSI
+
+      # Install dependencies using Spack
+      - name: install-dependencies-with-spack
+        if: steps.cache-env.outputs.cache-hit != 'true'
+        run: |
+          git clone -c feature.manyFiles=true https://github.com/NOAA-EMC/spack.git
+          source spack/share/spack/setup-env.sh
+          spack env create gsi-env GSI/ci/spack.yaml
+          spack env activate gsi-env
+          spack compiler find
+          spack external find
+          spack add intel-oneapi-mpi
+          spack concretize
+          spack install --dirty -v
+
+  build:
+    needs: setup
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: checkout-gsi
+        uses: actions/checkout@v2
+        with:
+            path: GSI
+
+      - name: install-intel
+        run: |
+          echo "source /opt/intel/oneapi/setvars.sh" >> ~/.bash_profile
+
+      - name: cache-env
+        id: cache-env
+        uses: actions/cache@v2
+        with:
+          path: |
+            spack
+            ~/.spack
+            /opt/intel
+          key: spack-${{ runner.os }}-${{ env.cache_key }}
+
+      - name: build-gsi
+        run: |
+          source spack/share/spack/setup-env.sh
+          spack env activate gsi-env
+          export CC=mpiicc
+          export FC=mpiifort
+          cd GSI
+          mkdir -p build && cd build
+          cmake -DCMAKE_INSTALL_PREFIX=../install -DGSI_MODE=Regional -DENKF_MODE=GFS -DBUILD_UTIL_ALL=ON -DBUILD_REG_TESTING=OFF -DBUILD_NCDIAG=OFF ..
+          make -j2 VERBOSE=1
+          make install
diff --git a/ci/spack.yaml b/ci/spack.yaml
new file mode 100644
index 0000000000..a69b21e92a
--- /dev/null
+++ b/ci/spack.yaml
@@ -0,0 +1,23 @@
+# Spack environment file to build GSI dependencies
+spack:
+  packages:
+    all:
+      compiler: [intel, gcc]
+  specs:
+  - netcdf-c@4.7.4
+  - netcdf-fortran@4.5.3
+  - bufr@11.5.0
+  - bacio@2.4.1
+  - w3emc@2.9.2
+  - sp@2.3.3
+  - ip@3.3.3
+  - sigio@2.3.2
+  - sfcio@1.4.1
+  - nemsio@2.5.2
+  - wrf-io@1.2.0
+  - ncio@1.0.0
+  - crtm@2.3.0
+  - gsi-ncdiag@1.0.0
+  view: true
+  concretizer:
+    unify: true