rhel84: remove excluded package if explicitly specified in the bp

When a users wants to install a package that itself is excluded or its
dependency is excluded, it fails the build. There is no known workaround
for this shorcoming of our current design.

Therefore, remove a package from the list of excluded if it is
explicitly mentioned in a blueprint. This will not solve the issue with
dependencies, but it will create a possibility of a workaround.

Also, introduce regression test to verify the bug fix and hook it into
CentOS CI (this issue was reported against RHEL, but CentOS runs on AWS
so it is better to verify the fix there).

internal/distro/rhel84/distro.go

@@ -217,7 +217,18 @@ func (t *imageType) Packages(bp blueprint.Blueprint) ([]string, []string) {
 		packages = removePackage(packages, "insights-client")
 	}
 
-	return packages, t.excludedPackages
+	// copy the list of excluded packages from the image type
+	// and subtract any packages found in the blueprint (this
+	// will not handle the issue with dependencies present in
+	// the list of excluded packages, but it will create a
+	// possibility of a workaround at least)
+	excludedPackages := append([]string(nil), t.excludedPackages...)
+	for _, pkg := range bp.GetPackages() {
+		// removePackage is fine if the package doesn't exist
+		excludedPackages = removePackage(excludedPackages, pkg)
+	}
+
+	return packages, excludedPackages
 }
 
 func (t *imageType) BuildPackages() []string {

schutzbot/Jenkinsfile

@@ -651,6 +651,10 @@ pipeline {
                     }
                     steps {
                         run_tests('base')
+                        sh (
+                            label: "Regression tests",
+                            script: "/usr/libexec/tests/osbuild-composer/regression.sh"
+                        )
                     }
                     post {
                         always {

test/cases/regression.sh

@@ -0,0 +1,53 @@
+#!/bin/bash
+set -xeuo pipefail
+
+# Provision the software under tet.
+/usr/libexec/osbuild-composer-test/provision.sh
+
+BLUEPRINT_FILE=/tmp/blueprint.toml
+COMPOSE_START=/tmp/compose-start.json
+COMPOSE_INFO=/tmp/compose-info.json
+
+# Write a basic blueprint for our image.
+tee "$BLUEPRINT_FILE" > /dev/null << EOF
+name = "redhat-lsb-core"
+description = "A base system with redhat-lsb-core"
+version = "0.0.1"
+
+[[packages]]
+name = "redhat-lsb-core"
+
+[[packages]]
+# The nss package is excluded in the RHEL8.4 image type, but it is required by the
+# redhat-lsb-core package. This test verifies it can be added again when explicitly
+# mentioned in the blueprint.
+name = "nss"
+EOF
+
+sudo composer-cli blueprints push "$BLUEPRINT_FILE"
+sudo composer-cli blueprints depsolve redhat-lsb-core
+sudo composer-cli --json compose start redhat-lsb-core qcow2 | tee "${COMPOSE_START}"
+COMPOSE_ID=$(jq -r '.build_id' "$COMPOSE_START")
+
+# Wait for the compose to finish.
+echo "⏱ Waiting for compose to finish: ${COMPOSE_ID}"
+while true; do
+    sudo composer-cli --json compose info "${COMPOSE_ID}" | tee "$COMPOSE_INFO" > /dev/null
+    COMPOSE_STATUS=$(jq -r '.queue_status' "$COMPOSE_INFO")
+
+    # Is the compose finished?
+    if [[ $COMPOSE_STATUS != RUNNING ]] && [[ $COMPOSE_STATUS != WAITING ]]; then
+        break
+    fi
+
+    # Wait 30 seconds and try again.
+    sleep 30
+done
+
+jq . "${COMPOSE_INFO}"
+
+# Did the compose finish with success?
+if [[ $COMPOSE_STATUS != FINISHED ]]; then
+    echo "Something went wrong with the compose. 😢"
+    exit 1
+fi