CI: logformatter: link to correct PR base

Two enormous misunderstandings:

  1) $CIRRUS_BASE_SHA is worthless. I thought it was, you know,
     the BASE SHA of the current commit, but (as best I can tell)
     it seems to be the SHA of the most recent commit on the
     destination branch. Cirrus docs are unhelpful. Anyhow,
     it's clearly not anything useful. Stop using it.

  2) $EPOCH_TEST_COMMIT is closer to what we want. It is
     defined in Makefile as the git merge-base. But for unknown
     reasons it was being clobbered in CI scripts, and it
     doesn't seem to work in all contexts, so, eliminate it
     from CI setup scripts. Leave it only in Makefile.

This leaves us with no option other than defining our own
merge-base variable, PR_BASE_SHA. Do so and pass it along
to rootless jobs.

Signed-off-by: Ed Santiago <[email protected]>

Makefile

@@ -276,7 +276,6 @@ help: ## (Default) Print listing of key targets with their descriptions
 
 .PHONY: lint
 lint: golangci-lint
-	@echo "Linting vs commit '$(call err_if_empty,EPOCH_TEST_COMMIT)'"
 ifeq ($(PRE_COMMIT),)
 	@echo "FATAL: pre-commit was not found, make .install.pre-commit to installing it." >&2
 	@exit 2

contrib/cirrus/lib.sh

@@ -71,30 +71,20 @@ export CI="${CI:-false}"
 CIRRUS_CI="${CIRRUS_CI:-false}"
 CONTINUOUS_INTEGRATION="${CONTINUOUS_INTEGRATION:-false}"
 CIRRUS_REPO_NAME=${CIRRUS_REPO_NAME:-podman}
-# Cirrus only sets $CIRRUS_BASE_SHA properly for PRs, but $EPOCH_TEST_COMMIT
-# needs to be set from this value in order for `make validate` to run properly.
-# When running get_ci_vm.sh, most $CIRRUS_xyz variables are empty. Attempt
-# to accommodate both branch and get_ci_vm.sh testing by discovering the base
-# branch SHA value.
+
 # shellcheck disable=SC2154
-if [[ -z "$CIRRUS_BASE_SHA" ]] && [[ -z "$CIRRUS_TAG" ]]
-then  # Operating on a branch, or under `get_ci_vm.sh`
-    showrun echo "branch or get_ci_vm (CIRRUS_BASE_SHA and CIRRUS_TAG are unset)"
-    CIRRUS_BASE_SHA=$(git rev-parse ${UPSTREAM_REMOTE:-origin}/$DEST_BRANCH)
-elif [[ -z "$CIRRUS_BASE_SHA" ]]
-then  # Operating on a tag
-    showrun echo "operating on tag"
-    CIRRUS_BASE_SHA=$(git rev-parse HEAD)
+if [[ -n "$CIRRUS_PR" ]] && [[ -z "$PR_BASE_SHA" ]]; then
+    # shellcheck disable=SC2154
+    PR_BASE_SHA=$(git merge-base ${DEST_BRANCH:-main} HEAD)
+    export PR_BASE_SHA
 fi
-# The starting place for linting and code validation
-EPOCH_TEST_COMMIT="$CIRRUS_BASE_SHA"
 
 # The next three values define regular expressions matching env. vars. necessary
 # for all possible testing contexts (rootless, container, etc.).  These values
 # are consumed by the passthrough_envars() automation library function.
 #
 # List of envariables which must be EXACT matches
-PASSTHROUGH_ENV_EXACT='CGROUP_MANAGER|DEST_BRANCH|DISTRO_NV|GOCACHE|GOPATH|GOSRC|NETWORK_BACKEND|OCI_RUNTIME|ROOTLESS_USER|SCRIPT_BASE|SKIP_USERNS|EC2_INST_TYPE|PODMAN_DB|STORAGE_FS|PODMAN_BATS_LEAK_CHECK'
+PASSTHROUGH_ENV_EXACT='CGROUP_MANAGER|DEST_BRANCH|DISTRO_NV|GOCACHE|GOPATH|GOSRC|NETWORK_BACKEND|OCI_RUNTIME|PR_BASE_SHA|ROOTLESS_USER|SCRIPT_BASE|SKIP_USERNS|EC2_INST_TYPE|PODMAN_DB|STORAGE_FS|PODMAN_BATS_LEAK_CHECK'
 
 # List of envariable patterns which must match AT THE BEGINNING of the name.
 # Consumed by the passthrough_envars() automation library function.

contrib/cirrus/logformatter

@@ -886,10 +886,13 @@ END_SYNOPSIS
     }
     $s .= _tr("Logs", join(" / ", @logs));
 
-    # BASE_SHA can tell us if our parent includes--or doesn't--a purported
-    # fix for a flake. Note that "commits", plural, links to a git history
-    # listing; if we used "commit", singular, that would be less useful.
-    $s .= _tr("Base commit", _a("{CIRRUS_BASE_SHA}", "https://{CIRRUS_REPO_CLONE_HOST}/{CIRRUS_REPO_FULL_NAME}/commits/{CIRRUS_BASE_SHA}"));
+    # PR_BASE_SHA (set in lib.sh) can tell us if our parent includes--or
+    # doesn't--a purported fix for a flake. Note about the URL: "commits", plural,
+    # links to a git history listing; if we used "commit", singular, that would
+    # be less useful.
+    if (my $base = $ENV{PR_BASE_SHA}) {
+        $s .= _tr("Base commit", _a($base, "https://{CIRRUS_REPO_CLONE_HOST}/{CIRRUS_REPO_FULL_NAME}/commits/$base"));
+    }
 
     $s .= "</table>\n";
     return $s;

contrib/cirrus/runner.sh

@@ -22,13 +22,8 @@ source $(dirname $0)/lib.sh
 showrun echo "starting"
 
 function _run_validate() {
-    # git-validation tool fails if $EPOCH_TEST_COMMIT is empty
-    # shellcheck disable=SC2154
-    if [[ -n "$EPOCH_TEST_COMMIT" ]]; then
-        showrun make validate
-    else
-        warn "Skipping git-validation since \$EPOCH_TEST_COMMIT is empty"
-    fi
+    showrun make validate
+
     # make sure PRs have tests
     showrun make tests-included
 }
@@ -257,7 +252,8 @@ function _run_altbuild() {
             context_dir=$(mktemp -d --tmpdir make-size-check.XXXXXXX)
             savedhead=$(git rev-parse HEAD)
             # Push to PR base. First run of the script will write size files
-            pr_base=$(git merge-base origin/$DEST_BRANCH HEAD)
+            # shellcheck disable=SC2154
+            pr_base=$PR_BASE_SHA
             showrun git checkout $pr_base
             showrun hack/make-and-check-size $context_dir
             # pop back to PR, and run incremental makes. Subsequent script
@@ -457,7 +453,9 @@ function _bail_if_test_can_be_skipped() {
     # Defined by Cirrus-CI for all tasks
     # shellcheck disable=SC2154
     head=$CIRRUS_CHANGE_IN_REPO
-    base=$(git merge-base $DEST_BRANCH $head)
+    # shellcheck disable=SC2154
+    base=$PR_BASE_SHA
+    echo "_bail_if_test_can_be_skipped: head=$head  base=$base"
     diffs=$(git diff --name-only $base $head)
 
     # If PR touches any files in an argument directory, we cannot skip