diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 99140bec170..9cf0f4dbd1e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,10 +51,12 @@ jobs:
             os: ubuntu-latest-xl
     timeout-minutes: 600
     runs-on: "${{ matrix.os }}"
+    defaults:
+      run:
+        shell: bash
     steps:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
-        shell: bash
       - name: checkout the source code
         uses: actions/checkout@v1
         with:
@@ -66,77 +68,59 @@ jobs:
         if: "success() && !env.SKIP_JOB && github.ref != 'refs/heads/try'"
       - name: add extra environment variables
         run: src/ci/scripts/setup-environment.sh
-        shell: bash
         env:
           EXTRA_VARIABLES: "${{ toJson(matrix.env) }}"
         if: success() && !env.SKIP_JOB
       - name: decide whether to skip this job
         run: src/ci/scripts/should-skip-this.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: collect CPU statistics
         run: src/ci/scripts/collect-cpu-stats.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: show the current environment
         run: src/ci/scripts/dump-environment.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install awscli
         run: src/ci/scripts/install-awscli.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install sccache
         run: src/ci/scripts/install-sccache.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install clang
         run: src/ci/scripts/install-clang.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install WIX
         run: src/ci/scripts/install-wix.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure the build happens on a partition with enough space
         run: src/ci/scripts/symlink-build-dir.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MSYS2
         run: src/ci/scripts/install-msys2.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install ninja
         run: src/ci/scripts/install-ninja.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: enable ipv6 on Docker
         run: src/ci/scripts/enable-docker-ipv6.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure line endings are correct
         run: src/ci/scripts/verify-line-endings.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: run the build
         run: src/ci/scripts/run-build-from-ci.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.CACHES_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}"
@@ -144,7 +128,6 @@ jobs:
         if: success() && !env.SKIP_JOB
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}"
@@ -170,10 +153,12 @@ jobs:
             env: {}
     timeout-minutes: 600
     runs-on: "${{ matrix.os }}"
+    defaults:
+      run:
+        shell: bash
     steps:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
-        shell: bash
       - name: checkout the source code
         uses: actions/checkout@v1
         with:
@@ -185,77 +170,59 @@ jobs:
         if: "success() && !env.SKIP_JOB && github.ref != 'refs/heads/try'"
       - name: add extra environment variables
         run: src/ci/scripts/setup-environment.sh
-        shell: bash
         env:
           EXTRA_VARIABLES: "${{ toJson(matrix.env) }}"
         if: success() && !env.SKIP_JOB
       - name: decide whether to skip this job
         run: src/ci/scripts/should-skip-this.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: collect CPU statistics
         run: src/ci/scripts/collect-cpu-stats.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: show the current environment
         run: src/ci/scripts/dump-environment.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install awscli
         run: src/ci/scripts/install-awscli.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install sccache
         run: src/ci/scripts/install-sccache.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install clang
         run: src/ci/scripts/install-clang.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install WIX
         run: src/ci/scripts/install-wix.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure the build happens on a partition with enough space
         run: src/ci/scripts/symlink-build-dir.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MSYS2
         run: src/ci/scripts/install-msys2.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install ninja
         run: src/ci/scripts/install-ninja.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: enable ipv6 on Docker
         run: src/ci/scripts/enable-docker-ipv6.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure line endings are correct
         run: src/ci/scripts/verify-line-endings.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: run the build
         run: src/ci/scripts/run-build-from-ci.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.CACHES_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}"
@@ -263,7 +230,6 @@ jobs:
         if: success() && !env.SKIP_JOB
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}"
@@ -507,10 +473,12 @@ jobs:
             os: windows-latest-xl
     timeout-minutes: 600
     runs-on: "${{ matrix.os }}"
+    defaults:
+      run:
+        shell: bash
     steps:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
-        shell: bash
       - name: checkout the source code
         uses: actions/checkout@v1
         with:
@@ -522,77 +490,59 @@ jobs:
         if: "success() && !env.SKIP_JOB && github.ref != 'refs/heads/try'"
       - name: add extra environment variables
         run: src/ci/scripts/setup-environment.sh
-        shell: bash
         env:
           EXTRA_VARIABLES: "${{ toJson(matrix.env) }}"
         if: success() && !env.SKIP_JOB
       - name: decide whether to skip this job
         run: src/ci/scripts/should-skip-this.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: collect CPU statistics
         run: src/ci/scripts/collect-cpu-stats.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: show the current environment
         run: src/ci/scripts/dump-environment.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install awscli
         run: src/ci/scripts/install-awscli.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install sccache
         run: src/ci/scripts/install-sccache.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install clang
         run: src/ci/scripts/install-clang.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install WIX
         run: src/ci/scripts/install-wix.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure the build happens on a partition with enough space
         run: src/ci/scripts/symlink-build-dir.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MSYS2
         run: src/ci/scripts/install-msys2.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install ninja
         run: src/ci/scripts/install-ninja.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: enable ipv6 on Docker
         run: src/ci/scripts/enable-docker-ipv6.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure line endings are correct
         run: src/ci/scripts/verify-line-endings.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: run the build
         run: src/ci/scripts/run-build-from-ci.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.CACHES_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}"
@@ -600,7 +550,6 @@ jobs:
         if: success() && !env.SKIP_JOB
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}"
@@ -652,10 +601,12 @@ jobs:
             os: macos-latest
     timeout-minutes: 600
     runs-on: "${{ matrix.os }}"
+    defaults:
+      run:
+        shell: bash
     steps:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
-        shell: bash
       - name: checkout the source code
         uses: actions/checkout@v1
         with:
@@ -667,77 +618,59 @@ jobs:
         if: "success() && !env.SKIP_JOB && github.ref != 'refs/heads/try'"
       - name: add extra environment variables
         run: src/ci/scripts/setup-environment.sh
-        shell: bash
         env:
           EXTRA_VARIABLES: "${{ toJson(matrix.env) }}"
         if: success() && !env.SKIP_JOB
       - name: decide whether to skip this job
         run: src/ci/scripts/should-skip-this.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: collect CPU statistics
         run: src/ci/scripts/collect-cpu-stats.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: show the current environment
         run: src/ci/scripts/dump-environment.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install awscli
         run: src/ci/scripts/install-awscli.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install sccache
         run: src/ci/scripts/install-sccache.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install clang
         run: src/ci/scripts/install-clang.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install WIX
         run: src/ci/scripts/install-wix.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure the build happens on a partition with enough space
         run: src/ci/scripts/symlink-build-dir.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MSYS2
         run: src/ci/scripts/install-msys2.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: install ninja
         run: src/ci/scripts/install-ninja.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: enable ipv6 on Docker
         run: src/ci/scripts/enable-docker-ipv6.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: ensure line endings are correct
         run: src/ci/scripts/verify-line-endings.sh
-        shell: bash
         if: success() && !env.SKIP_JOB
       - name: run the build
         run: src/ci/scripts/run-build-from-ci.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.CACHES_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}"
@@ -745,7 +678,6 @@ jobs:
         if: success() && !env.SKIP_JOB
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: "${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}"
           AWS_SECRET_ACCESS_KEY: "${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}"
diff --git a/src/ci/github-actions/ci.yml b/src/ci/github-actions/ci.yml
index 0b3b77f217d..e8036b8c120 100644
--- a/src/ci/github-actions/ci.yml
+++ b/src/ci/github-actions/ci.yml
@@ -75,11 +75,13 @@ x--expand-yaml-anchors--remove:
   - &base-ci-job
     timeout-minutes: 600
     runs-on: "${{ matrix.os }}"
+    defaults:
+      run:
+        shell: bash
     env: *shared-ci-variables
     steps:
       - name: disable git crlf conversion
         run: git config --global core.autocrlf false
-        shell: bash
 
       - name: checkout the source code
         uses: actions/checkout@v1
@@ -95,7 +97,6 @@ x--expand-yaml-anchors--remove:
 
       - name: add extra environment variables
         run: src/ci/scripts/setup-environment.sh
-        shell: bash
         env:
           # Since it's not possible to merge `${{ matrix.env }}` with the other
           # variables in `job.<name>.env`, the variables defined in the matrix
@@ -106,67 +107,54 @@ x--expand-yaml-anchors--remove:
 
       - name: decide whether to skip this job
         run: src/ci/scripts/should-skip-this.sh
-        shell: bash
         <<: *step
 
       - name: collect CPU statistics
         run: src/ci/scripts/collect-cpu-stats.sh
-        shell: bash
         <<: *step
 
       - name: show the current environment
         run: src/ci/scripts/dump-environment.sh
-        shell: bash
         <<: *step
 
       - name: install awscli
         run: src/ci/scripts/install-awscli.sh
-        shell: bash
         <<: *step
 
       - name: install sccache
         run: src/ci/scripts/install-sccache.sh
-        shell: bash
         <<: *step
 
       - name: install clang
         run: src/ci/scripts/install-clang.sh
-        shell: bash
         <<: *step
 
       - name: install WIX
         run: src/ci/scripts/install-wix.sh
-        shell: bash
         <<: *step
 
       - name: ensure the build happens on a partition with enough space
         run: src/ci/scripts/symlink-build-dir.sh
-        shell: bash
         <<: *step
 
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         <<: *step
 
       - name: install MSYS2
         run: src/ci/scripts/install-msys2.sh
-        shell: bash
         <<: *step
 
       - name: install MinGW
         run: src/ci/scripts/install-mingw.sh
-        shell: bash
         <<: *step
 
       - name: install ninja
         run: src/ci/scripts/install-ninja.sh
-        shell: bash
         <<: *step
 
       - name: enable ipv6 on Docker
         run: src/ci/scripts/enable-docker-ipv6.sh
-        shell: bash
         <<: *step
 
       # Disable automatic line ending conversion (again). On Windows, when we're
@@ -176,22 +164,18 @@ x--expand-yaml-anchors--remove:
       # appropriate line endings.
       - name: disable git crlf conversion
         run: src/ci/scripts/disable-git-crlf-conversion.sh
-        shell: bash
         <<: *step
 
       - name: checkout submodules
         run: src/ci/scripts/checkout-submodules.sh
-        shell: bash
         <<: *step
 
       - name: ensure line endings are correct
         run: src/ci/scripts/verify-line-endings.sh
-        shell: bash
         <<: *step
 
       - name: run the build
         run: src/ci/scripts/run-build-from-ci.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: ${{ env.CACHES_AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.CACHES_AWS_ACCESS_KEY_ID)] }}
@@ -200,7 +184,6 @@ x--expand-yaml-anchors--remove:
 
       - name: upload artifacts to S3
         run: src/ci/scripts/upload-artifacts.sh
-        shell: bash
         env:
           AWS_ACCESS_KEY_ID: ${{ env.ARTIFACTS_AWS_ACCESS_KEY_ID }}
           AWS_SECRET_ACCESS_KEY: ${{ secrets[format('AWS_SECRET_ACCESS_KEY_{0}', env.ARTIFACTS_AWS_ACCESS_KEY_ID)] }}