Merge branch 'keep-kernel-size' into 'main'

Configure the amount of kernels to keep

See merge request apt-team/apt!324

3 files changed, 76 insertions, 13 deletions

diff --git a/apt-pkg/algorithms.cc b/apt-pkg/algorithms.cc
index d841d6dd8..24a41b70a 100644
--- a/apt-pkg/algorithms.cc
+++ b/apt-pkg/algorithms.cc
@@ -1574,30 +1574,37 @@ std::string GetProtectedKernelsRegex(pkgCache *cache, bool ReturnRemove)
    if (version2unames.size() == 0)
       return "";
 
-   auto latest = version2unames.rbegin();
-   auto previous = latest;
-   ++previous;
-
+   auto versions = version2unames.rbegin();
    std::set<std::string> keep;
 
+   auto keepKernels = (unsigned long)_config->FindI("APT::NeverAutoRemove::KernelCount", 2);
+   if (keepKernels < 2)
+      keepKernels = 2;
+
+   if (Debug)
+      std::clog << "Amount of kernels to keep " << keepKernels << std::endl;
+
    if (not bootedVersion.empty())
    {
       if (Debug)
 	 std::clog << "Keeping booted kernel " << bootedVersion << std::endl;
       keep.insert(bootedVersion);
    }
-   if (latest != version2unames.rend())
-   {
-      if (Debug)
-	 std::clog << "Keeping latest kernel " << latest->first << std::endl;
-      keep.insert(latest->first);
-   }
-   if (keep.size() < 2 && previous != version2unames.rend())
+
+   while (keep.size() < keepKernels && versions != version2unames.rend())
    {
+      auto v = versions->first;
+      if (v == bootedVersion)
+      {
+	 versions++;
+	 continue;
+      }
       if (Debug)
-	 std::clog << "Keeping previous kernel " << previous->first << std::endl;
-      keep.insert(previous->first);
+	 std::clog << "Keeping previous kernel " << v << std::endl;
+      keep.insert(v);
+      versions++;
    }
+
    // Escape special characters '.' and '+' in version strings so we can build a regular expression
    auto escapeSpecial = [](std::string input) -> std::string {
       for (size_t pos = 0; (pos = input.find_first_of(".+", pos)) != input.npos; pos += 2) {
diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml
index 7e7d64f8d..46f05d42e 100644
--- a/doc/apt.conf.5.xml
+++ b/doc/apt.conf.5.xml
@@ -311,6 +311,61 @@ APT::Compressor::rev {
      <listitem><para>The CDROM subsection controls the &apt-cdrom; tool; please see its
      documentation for more information about the options here.</para></listitem>
      </varlistentry>
+
+    <varlistentry>
+        <term>
+            <option>NeverAutoRemove</option>
+        </term>
+        <listitem>
+            <para>
+                Never autoremove packages that match the regular expression(s).
+            </para>
+        </listitem>
+    </varlistentry>
+
+    <varlistentry>
+        <term>
+            <option>Protect-Kernels</option>
+        </term>
+        <listitem>
+            <para>
+                This option tells apt autoremove that kernels are protected and
+                defaults to true. In case kernels are not protected they are
+                treated as any other package.
+            </para>
+        </listitem>
+    </varlistentry>
+
+    <varlistentry>
+        <term>
+            <option>VersionedKernelPackages</option>
+        </term>
+        <listitem>
+            <para>
+                Define the regular expression(s) for versioned kernel packages.
+                Based on these expressions a rule set is injected into apt
+                similar to APT::NeverAutoRemove regular expressions.
+            </para>
+        </listitem>
+    </varlistentry>
+
+    <varlistentry>
+        <term>
+            <option>NeverAutoRemove::KernelCount</option>
+        </term>
+        <listitem>
+            <para>
+                Keep a custom amount of kernels when autoremoving and defaults
+                to 2, meaning two kernels are kept. Apt will always keep the
+                running kernel and the latest one. If the latest kernel is the
+                same as the running kernel, the second latest kernel is kept.
+                Because of this, any value lower than 2 will be ignored. If you
+                want only the latest kernel, you should set
+                APT::Protect-Kernels to false.
+            </para>
+        </listitem>
+    </varlistentry>
+
    </variablelist>
  </refsect1>
 
diff --git a/doc/examples/configure-index b/doc/examples/configure-index
index 0d4dd31a5..f37b7696c 100644
--- a/doc/examples/configure-index
+++ b/doc/examples/configure-index
@@ -55,6 +55,7 @@ APT
   Build-Profiles "<STRING_OR_LIST>";
 
   NeverAutoRemove "<LIST>";  // list of package name regexes
+  NeverAutoRemove::KernelCount "<INT>"; // Keep the configured amount of kernels
   LastInstalledKernel "<STRING>"; // last installed kernel version
   VersionedKernelPackages "<LIST>"; // regular expressions to be protected from autoremoval (kernel uname will be appended)
   Protect-Kernels "<BOOL>"; // whether to protect installed kernels against autoremoval (default: true)