ci: test against supported rhel distribs

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

.github/workflows/build.yml

@@ -59,10 +59,26 @@ jobs:
             image: debian:sid
             typ: debian
             allow-failure: true
+          -
+            image: redhat/ubi8
+            typ: rhel
+            allow-failure: false
           -
             image: fedora:35
             typ: rhel
             allow-failure: false
+          -
+            image: centos:8
+            typ: rhel
+            allow-failure: false
+          -
+            image: rockylinux/rockylinux:8
+            typ: rhel
+            allow-failure: false
+          -
+            image: oraclelinux:8
+            typ: rhel
+            allow-failure: false
     steps:
       -
         name: Checkout

base/Dockerfile

@@ -1,4 +1,5 @@
-#syntax=docker/dockerfile:1.2
+# syntax=docker/dockerfile:1.3-labs
+
 ARG TEST_BASE_TYPE=alpine
 ARG TEST_BASE_IMAGE=${TEST_BASE_TYPE}
 ARG TEST_WITH_DARWIN=false
@@ -33,6 +34,16 @@ RUN --mount=type=cache,target=/pkg-cache \
 WORKDIR /work
 
 FROM ${TEST_BASE_IMAGE} AS test-base-rhel
+RUN <<EOT
+#!/usr/bin/env bash
+if ! yum install -y epel-release; then
+  if . /etc/os-release 2>/dev/null; then
+    if [ "$ID" != "fedora" ]; then
+      yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-${VERSION:0:1}.noarch.rpm
+    fi
+  fi
+fi
+EOT
 RUN --mount=type=cache,target=/pkg-cache \
     rm -rf /var/cache/yum && \
     ln -s /pkg-cache /var/cache/yum && \

base/test-info-rhel.bats

@@ -2,8 +2,19 @@
 
 load "assert"
 
+vendor="rhel"
+if grep <"/etc/redhat-release" "Fedora" 2>/dev/null >/dev/null; then
+  vendor="fedora"
+elif grep <"/etc/redhat-release" "CentOS" 2>/dev/null >/dev/null; then
+  vendor="centos"
+elif grep <"/etc/redhat-release" "Rocky Linux" 2>/dev/null >/dev/null; then
+  vendor="rocky"
+elif [ -f "/etc/oracle-release" ] && grep <"/etc/oracle-release" "Oracle Linux" 2>/dev/null >/dev/null; then
+  vendor="ol"
+fi
+
 @test "vendor" {
-  assert_equal "fedora" "$(xx-info vendor)"
+  assert_equal "$vendor" "$(xx-info vendor)"
 }
 
 @test "rhel-arch" {