diff --git a/.github/workflows/codecov.yml b/.github/workflows/codecov.yml
index 523002644f5..1d241b47725 100644
--- a/.github/workflows/codecov.yml
+++ b/.github/workflows/codecov.yml
@@ -9,7 +9,7 @@ permissions: read-all
 jobs:
   test:
     name: Code Coverage
-    runs-on: gh-hosted-runners-4cores-1
+    runs-on: gh-hosted-runners-16cores-1
 
     steps:
     - name: Check out code
@@ -106,8 +106,14 @@ jobs:
 
         eatmydata -- make unit_test_cover
 
+        # Restore the files we deleted as codecov tries to fix their paths.
+        git reset --hard HEAD
+
     - name: Upload coverage reports to codecov.io
       if: steps.changes.outputs.changed_files == 'true'
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v4
+      with:
+        fail_ci_if_error: true
+        verbose: true
       env:
         CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
diff --git a/Makefile b/Makefile
index 7b09549ae79..e32204733f4 100644
--- a/Makefile
+++ b/Makefile
@@ -216,7 +216,7 @@ e2e_test: build
 # Run the code coverage tools, compute aggregate.
 unit_test_cover: build dependency_check demo
 	source build.env
-	go test $(VT_GO_PARALLEL) -count=1 -coverprofile=coverage.out ./go/...
+	go test $(VT_GO_PARALLEL) -count=1 -failfast -covermode=atomic -coverpkg=vitess.io/vitess/go/... -coverprofile=coverage.out ./go/...
 	# Handle go tool cover failures due to not handling `//line` directives, which
 	# the goyacc compiler adds to the generated parser in sql.go. See:
 	# https://github.com/golang/go/issues/41222
diff --git a/codecov.yml b/codecov.yml
new file mode 100644
index 00000000000..61232ae9197
--- /dev/null
+++ b/codecov.yml
@@ -0,0 +1,50 @@
+# https://docs.codecov.com/docs/
+# https://docs.codecov.com/docs/codecov-yaml
+
+codecov:
+  branch: main # Set the default branch
+
+parsers:
+  go:
+    partials_as_hits: true
+
+ignore:
+  # Ignore our end-to-end test code
+  - "go/flags/endtoend/**"
+  - "go/mysql/endtoend/**"
+  - "go/test/endtoend/**"
+  - "go/vt/vtctl/endtoend/**"
+  - "go/vt/vtctl/grpcvtctldserver/endtoend/**"
+  - "go/vt/vtgate/endtoend/**"
+  - "go/vt/vttablet/endtoend/**"
+  - "go/cmd/vttestserver/**" # This relies on end-to-end test packages
+  # Ignore generated code
+  - "go/**/cached_size.go" # Code generated by Sizegen
+  - "go/vt/sqlparser/ast_clone.go" # Code generated by ASTHelperGen
+  - "go/vt/sqlparser/ast_copy_on_rewrite.go" # Code generated by ASTHelperGen
+  - "go/vt/sqlparser/ast_equals.go" # Code generated by ASTHelperGen
+  - "go/vt/sqlparser/ast_format_fast.go" # Code generated by ASTFmtGen
+  - "go/vt/sqlparser/ast_rewrite.go" # Code generated by ASTHelperGen
+  - "go/vt/sqlparser/ast_visit.go" # Code generated by ASTHelperGen
+  - "go/vt/vttablet/tabletserver/txthrottler/mock_healthcheck_test.go" # Code generated by MockGen
+  - "go/vt/vttablet/tabletserver/txthrottler/mock_throttler_test.go" # Code generated by MockGen
+  - "go/vt/sqlparser/sql.go" # Code generated by goyacc
+  - "go/mysql/collations/charset/korean/tables.go" # Code generated by go run maketables.go
+  - "go/mysql/collations/charset/simplifiedchinese/tables.go" # Code generated by go run maketables.go
+  - "go/mysql/collations/colldata/mysqldata.go" # Code generated by makecolldata
+  - "go/mysql/collations/colldata/mysqlucadata.go" # Code generated by makecolldata
+  - "go/mysql/collations/internal/uca/fasttables.go" # Code generated by makecolldata
+  - "go/mysql/collations/mysqlversion.go" # Code generated by makecolldata
+  - "go/mysql/collations/supported.go" # Code generated by makecolldata
+  # Ignore proto files
+  - "go/vt/proto/**"
+
+comment: # https://docs.codecov.com/docs/pull-request-comments
+    hide_project_coverage: false
+
+coverage:
+  status: # https://docs.codecov.com/docs/commit-status
+    project:
+      default:
+        informational: true # Don't ever fail the codecov/project or codecov/patch tests
+
diff --git a/go/tools/releases/releases_test.go b/go/tools/releases/releases_test.go
index 7d050d7c964..19b3f7df88e 100644
--- a/go/tools/releases/releases_test.go
+++ b/go/tools/releases/releases_test.go
@@ -38,14 +38,6 @@ func TestGetDirs(t *testing.T) {
 			currentDir: dir{
 				Path: "./",
 			},
-			expectedErr: "",
-		},
-		{
-			name: "Temp dir",
-			currentDir: dir{
-				Path: "/tmp",
-			},
-			expectedErr: "open /tmp/snap-private-tmp: permission denied",
 		},
 	}
 
diff --git a/go/vt/vttablet/tabletserver/report.xml b/go/vt/vttablet/tabletserver/report.xml
deleted file mode 100644
index e69de29bb2d..00000000000
diff --git a/go/vt/wrangler/vexec.go b/go/vt/wrangler/vexec.go
index 49b6c442f60..2c279c5c6cf 100644
--- a/go/vt/wrangler/vexec.go
+++ b/go/vt/wrangler/vexec.go
@@ -880,8 +880,9 @@ func (wr *Wrangler) ListAllWorkflows(ctx context.Context, keyspace string, activ
 }
 
 // ShowWorkflow will return all of the relevant replication related information for the given workflow.
-func (wr *Wrangler) ShowWorkflow(ctx context.Context, workflow, keyspace string, shards []string) (*ReplicationStatusResult, error) {
-	replStatus, err := wr.getStreams(ctx, workflow, keyspace, shards)
+// If shardSubset is nil, then all shards will be queried.
+func (wr *Wrangler) ShowWorkflow(ctx context.Context, workflow, keyspace string, shardSubset []string) (*ReplicationStatusResult, error) {
+	replStatus, err := wr.getStreams(ctx, workflow, keyspace, shardSubset)
 	if err != nil {
 		return nil, err
 	}