stages/kickstart: post-installation scripts

Add a new %post option to the kickstart stage that supports adding
multiple post blocks to a kickstart file, with all the options supported
by the directive.

stages/org.osbuild.kickstart

@@ -170,6 +170,25 @@ def make_network(options: Dict) -> List[str]:
     return res
 
 
+def make_post(post_list):
+    res = []
+    for post in post_list:
+        start = ["%post"]
+        if post.get("erroronfail"):
+            start.append("--erroronfail")
+        if post.get("nochroot"):
+            start.append("--nochroot")
+        log = post.get("log")
+        if log:
+            start.extend(["--log", f'"{log}"'])
+        interpreter = post.get("interpreter")
+        if interpreter:
+            start.extend(["--interpreter", f'"{interpreter}"'])
+
+        res.extend([" ".join(start), *post["commands"], "%end"])
+    return res
+
+
 def main(tree, options):  # pylint: disable=too-many-branches
     path = options["path"].lstrip("/")
     ostree = options.get("ostree")
@@ -242,6 +261,9 @@ def main(tree, options):  # pylint: disable=too-many-branches
     kargs_append = options.get("bootloader", {}).get("append")
     if kargs_append:
         config += [f"bootloader --append='{kargs_append}'"]
+    post = options.get("%post", [])
+    if post:
+        config += make_post(post)
 
     target = os.path.join(tree, path)
     base = os.path.dirname(target)

stages/org.osbuild.kickstart.meta.json

@@ -555,6 +555,43 @@
             "type": "string"
           }
         }
+      },
+      "%post": {
+        "type": "array",
+        "minItems": 1,
+        "items": {
+          "type": "object",
+          "description": "Adds arbitrary commands to run on the system once the installation is complete.",
+          "additionalProperties": false,
+          "required": [
+            "commands"
+          ],
+          "properties": {
+            "erroronfail": {
+              "description": "Stop the installation on script failure",
+              "type": "boolean"
+            },
+            "interpreter": {
+              "description": "Allows specifying a different scripting language",
+              "type": "string"
+            },
+            "log": {
+              "description": "Log all messages from the script to the given log file",
+              "type": "string"
+            },
+            "nochroot": {
+              "description": "Run outside of the chroot environment",
+              "type": "boolean"
+            },
+            "commands": {
+              "type": "array",
+              "minItems": 1,
+              "items": {
+                "type": "string"
+              }
+            }
+          }
+        }
       }
     }
   }

stages/test/test_kickstart.py

@@ -241,6 +241,47 @@ TEST_INPUT = [
     ({"ostreecontainer": {"transport": "dir", "url": "/run/install/repo/container", }, },
      "ostreecontainer --url=/run/install/repo/container --transport=dir",),
     ({"bootloader": {"append": "karg1 karg2=0"}}, "bootloader --append='karg1 karg2=0'"),
+
+    # %post
+    ({"%post": [{"commands": ["mkdir /scratch"]}]}, "%post\nmkdir /scratch\n%end"),
+    (
+        {
+            "%post": [
+                {"commands": ["mkdir /scratch"]},
+                {"commands": ["print('DONE!!!')"], "interpreter": "/usr/bin/python3"},
+            ]
+        },
+        "%post\nmkdir /scratch\n%end\n" +
+        "%post --interpreter \"/usr/bin/python3\"\nprint('DONE!!!')\n%end"
+    ),
+    (
+        {
+            "%post": [
+                {"commands": ["mkdir /scratch"]},
+                {
+                    "erroronfail": True,
+                    "nochroot": True,
+                    "interpreter": "/usr/bin/bash",
+                    "log": "/mnt/sysimage/var/log/ks-p2.log",
+                    "commands": [
+                        "echo 'Starting post2'",
+                        "if [ ! -e /mnt/sysimage/etc/resolv.conf ]; then",
+                        "  cp /etc/resolv.conf /mnt/sysimage/etc/resolv.conf",
+                        "fi",
+                    ]
+                },
+                {"commands": ["print('DONE!!!')"], "interpreter": "/usr/bin/python3"},
+            ]
+        },
+        "%post\nmkdir /scratch\n%end\n" +
+        "%post --erroronfail --nochroot --log \"/mnt/sysimage/var/log/ks-p2.log\" --interpreter \"/usr/bin/bash\"\n" +
+        "echo 'Starting post2'\n" +
+        "if [ ! -e /mnt/sysimage/etc/resolv.conf ]; then\n" +
+        "  cp /etc/resolv.conf /mnt/sysimage/etc/resolv.conf\n" +
+        "fi\n" +
+        "%end\n" +
+        "%post --interpreter \"/usr/bin/python3\"\nprint('DONE!!!')\n%end"
+    )
 ]
 
 
@@ -387,6 +428,10 @@ def test_kickstart_valid(tmp_path, stage_module, test_input, expected):  # pylin
             {"rootpw": {"iscrypted": True, "plaintext": True, "password": "pass"}},
             "is not valid under any of the given schemas"
         ),
+        # bad %post blocks
+        ({"%post": []}, re.compile(r"\[\] should be non-empty|\[\] is too short")),
+        ({"%post": [{}]}, "'commands' is a required property"),
+        ({"%post": [{"commands": []}]}, re.compile(r"\[\] should be non-empty|\[\] is too short")),
     ],
 )
 @pytest.mark.parametrize("stage_schema", ["1"], indirect=True)