utilities: add useGetHostDistro hook

Add a hook that gets the host distro for the on-prem frontend. If there
is an issue we will fallback to the default. For the service we also
just use the default distro.

src/Components/CreateImageWizard/steps/ImageOutput/ReleaseSelect.tsx

@@ -17,6 +17,7 @@ import {
   RHEL_9_FULL_SUPPORT,
   RHEL_9_MAINTENANCE_SUPPORT,
   RHEL_10_BETA,
+  ON_PREM_RELEASES,
 } from '../../../../constants';
 import { useAppDispatch, useAppSelector } from '../../../../store/hooks';
 import { Distributions } from '../../../../store/imageBuilderApi';
@@ -27,6 +28,7 @@ import {
 import isRhel from '../../../../Utilities/isRhel';
 import { toMonthAndYear } from '../../../../Utilities/time';
 import { useFlag } from '../../../../Utilities/useGetEnvironment';
+import { useGetHostDistro } from '../../../../Utilities/useGetHostDistro';
 
 const ReleaseSelect = () => {
   // What the UI refers to as the "release" is referred to as the "distribution" in the API.
@@ -36,6 +38,7 @@ const ReleaseSelect = () => {
   const dispatch = useAppDispatch();
   const [isOpen, setIsOpen] = useState(false);
   const [showDevelopmentOptions, setShowDevelopmentOptions] = useState(false);
+  const hostDistro = useGetHostDistro(distribution);
 
   const isRHEL9BetaEnabled = useFlag('image-builder.rhel9.beta.enabled');
   const isRHEL10BetaEnabled = useFlag('image-builder.rhel10.beta.enabled');
@@ -74,8 +77,13 @@ const ReleaseSelect = () => {
 
   const setSelectOptions = () => {
     const options: ReactElement[] = [];
+    const releases = process.env.IS_ON_PREMISE ? ON_PREM_RELEASES : RELEASES;
     const filteredRhel = new Map(
-      [...RELEASES].filter(([key]) => {
+      [...releases].filter(([key]) => {
+        if (process.env.IS_ON_PREMISE) {
+          return key === hostDistro;
+        }
+
         if (key === RHEL_9_BETA) {
           return isRHEL9BetaEnabled;
         }
@@ -114,14 +122,17 @@ const ReleaseSelect = () => {
         variant={SelectVariant.single}
         onToggle={() => setIsOpen(!isOpen)}
         onSelect={handleSelect}
-        selections={RELEASES.get(distribution)}
+        selections={RELEASES.get(hostDistro)}
         isOpen={isOpen}
-        {...(!showDevelopmentOptions && {
-          loadingVariant: {
-            text: 'Show options for further development of RHEL',
-            onClick: handleExpand,
-          },
-        })}
+        {...(!showDevelopmentOptions &&
+          // Hide this for on-prem since the host
+          // could be centos or fedora
+          !process.env.IS_ON_PREMISE && {
+            loadingVariant: {
+              text: 'Show options for further development of RHEL',
+              onClick: handleExpand,
+            },
+          })}
       >
         {setSelectOptions()}
       </Select>

src/Utilities/useGetHostDistro.ts

@@ -0,0 +1,51 @@
+import { useEffect, useState } from 'react';
+
+import path from 'path';
+
+import cockpit from 'cockpit';
+
+import { CENTOS_10, FEDORA_41, RHEL_10_BETA } from '../constants';
+import { Distributions } from '../store/imageBuilderApi';
+
+export const useGetHostDistro = (distribution: Distributions) => {
+  const [distro, setDistro] = useState(distribution);
+
+  useEffect(() => {
+    const getHostDistro = async () => {
+      try {
+        const file = cockpit.file(path.join('/', 'etc', 'os-release'));
+        const contents = await file.read();
+        file.close();
+
+        // TOML parse fails on certain distros
+        // so this is the best way of getting the
+        // name of the host distro
+        const [distroName] = contents
+          .split('\n')
+          .filter((line) => line.startsWith('NAME='));
+
+        if (distroName === 'NAME="Red Hat Enterprise Linux"') {
+          // TODO: add RHEL 10
+          setDistro(RHEL_10_BETA);
+        }
+
+        if (distroName === 'NAME="CentOS Stream"') {
+          setDistro(CENTOS_10);
+        }
+
+        if (distroName === 'NAME="Fedora Linux"') {
+          setDistro(FEDORA_41);
+        }
+      } finally {
+        // do nothing, just use the default distribution
+      }
+    };
+
+    // don't call this function for the service
+    if (process.env.IS_ON_PREMISE) {
+      getHostDistro();
+    }
+  });
+
+  return distro;
+};