diff --git a/.github/buildomat/jobs/build-and-test.sh b/.github/buildomat/jobs/build-and-test.sh
index 99983f7a979..727914a3e2b 100644
--- a/.github/buildomat/jobs/build-and-test.sh
+++ b/.github/buildomat/jobs/build-and-test.sh
@@ -2,7 +2,7 @@
 #:
 #: name = "helios / build-and-test"
 #: variety = "basic"
-#: target = "helios"
+#: target = "helios-latest"
 #: rust_toolchain = "nightly-2022-04-27"
 #: output_rules = []
 #:
@@ -14,12 +14,6 @@ set -o xtrace
 cargo --version
 rustc --version
 
-banner clickhouse
-ptime -m ./tools/ci_download_clickhouse
-
-banner cockroach
-ptime -m bash ./tools/ci_download_cockroachdb
-
 #
 # Set up a custom temporary directory within whatever one we were given so that
 # we can check later whether we left detritus around.
@@ -34,6 +28,9 @@ mkdir $TEST_TMPDIR
 #
 export PATH="$PATH:$PWD/out/cockroachdb/bin:$PWD/out/clickhouse"
 
+banner prerequisites
+ptime -m bash ./tools/install_prerequisites.sh -y
+
 #
 # We build with:
 #
diff --git a/.github/workflows/rust.yml b/.github/workflows/rust.yml
index 17fafc128ac..d8af3b92e4d 100644
--- a/.github/workflows/rust.yml
+++ b/.github/workflows/rust.yml
@@ -102,26 +102,10 @@ jobs:
 
         echo "Disk space:"
         df -h
-    - name: Configure GitHub cache for CockroachDB binaries
-      id: cache-cockroachdb
-      # actions/cache@v2.1.4
-      uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6
-      with:
-        key: ${{ runner.os }}-cockroach-binary-${{ hashFiles('tools/cockroachdb_checksums') }}
-        path: "./out/cockroachdb"
-    - name: Configure GitHub cache for ClickHouse binaries
-      id: cache-clickhouse
-      # actions/cache@v2.1.4
-      uses: actions/cache@26968a09c0ea4f3e233fdddbafd1166051a095f6
-      with:
-        key: ${{ runner.os }}-clickhouse-binary-${{ hashFiles('tools/clickhouse_checksums') }}
-        path: "./out/clickhouse"
-    - name: Download ClickHouse
-      if: steps.cache-clickhouse.outputs.cache-hit != 'true'
-      run: ./tools/ci_download_clickhouse
-    - name: Download CockroachDB binary
-      if: steps.cache-cockroachdb.outputs.cache-hit != 'true'
-      run: bash ./tools/ci_download_cockroachdb
+    - name: Update PATH
+      run: echo "$PWD/out/cockroachdb/bin:$PWD/out/clickhouse" >> "$GITHUB_PATH"
+    - name: Install Pre-Requisites
+      run: ./tools/install_prerequisites.sh -y
     - name: Create temporary directory for test outputs
       run: mkdir -p $OMICRON_TMP
     - name: Build
@@ -138,13 +122,11 @@ jobs:
       # - TMPDIR=$OMICRON_TMP: we specify a specific temporary directory so that
       #   failed test outputs will be in a known place that we can grab at the
       #   end without also grabbing random other temporary files.
-      run: TMPDIR=$OMICRON_TMP PATH="$PATH:$PWD/out/cockroachdb/bin:$PWD/out/clickhouse" RUSTFLAGS="-D warnings" RUSTDOCFLAGS="-D warnings" cargo build --locked --all-targets --verbose
+      run: TMPDIR=$OMICRON_TMP RUSTFLAGS="-D warnings" RUSTDOCFLAGS="-D warnings" cargo build --locked --all-targets --verbose
     - name: Run tests
       # Use the same RUSTFLAGS and RUSTDOCFLAGS as above to avoid having to
       # rebuild here.
-      # Put "./cockroachdb/bin" and "./clickhouse" on the PATH for the test
-      # suite.
-      run: TMPDIR=$OMICRON_TMP PATH="$PATH:$PWD/out/cockroachdb/bin:$PWD/out/clickhouse" RUSTFLAGS="-D warnings" RUSTDOCFLAGS="-D warnings" cargo test --no-fail-fast --workspace --locked --verbose
+      run: TMPDIR=$OMICRON_TMP RUSTFLAGS="-D warnings" RUSTDOCFLAGS="-D warnings" cargo test --no-fail-fast --workspace --locked --verbose
     - name: Archive results left by tests
       # actions/upload-artifact@v2.3.1
       uses: actions/upload-artifact@82c141cc518b40d92cc801eee768e7aafc9c2fa2
diff --git a/tools/ci_download_console b/tools/ci_download_console
index 307fcadf4eb..e81586c5831 100755
--- a/tools/ci_download_console
+++ b/tools/ci_download_console
@@ -79,7 +79,16 @@ function do_download_curl
 
 function do_sha256sum
 {
-	sha256sum < "$1" | awk '{print $1}'
+	case "$OSTYPE" in
+		darwin*)
+			SHA="shasum -a 256"
+			;;
+		*)
+			SHA="sha256sum"
+			;;
+	esac
+
+	$SHA < "$1" | awk '{print $1}'
 }
 
 function do_untar
diff --git a/tools/install_prerequisites.sh b/tools/install_prerequisites.sh
index c348c6d971a..056e4f7af0b 100755
--- a/tools/install_prerequisites.sh
+++ b/tools/install_prerequisites.sh
@@ -123,7 +123,6 @@ fi
 ./tools/ci_download_cockroachdb
 ./tools/ci_download_clickhouse
 
-
 # Install static console assets. These are used when packaging Nexus.
 ./tools/ci_download_console