Configure journal-remote limits properly

Let's make sure the limits are configured so we can always write at
least 4G of logs. We also enable compact mode again in all cases to
reduce the size used by journal files as for example Github Actions
machines aren't exactly swimming in free space.

(We pick 4G because that's the max journal file size when the compact
mode is used)

(We'll probably have to revisit this again at some point but for now
this should do the trick)

diff --git a/mkosi/qemu.py b/mkosi/qemu.py
index 9b87dc175e09f137e61aece2a658c9ff61cb3351..f663917b8540e2eca98628df98da5e0736877536 100644 (file)
--- a/mkosi/qemu.py
+++ b/mkosi/qemu.py
@@ -18,6 +18,7 @@ import struct
 import subprocess
 import sys
 import tempfile
+import textwrap
 import uuid
 from collections.abc import Iterator, Sequence
 from pathlib import Path
@@ -430,31 +431,49 @@ def start_journal_remote(config: Config, sockfd: int) -> Iterator[None]:
         run(["chattr", "+C", d], check=False, stderr=subprocess.DEVNULL if not ARG_DEBUG.get() else None)
         INVOKING_USER.chown(d)
 
-    with spawn(
-        [
-            bin,
-            "--output", config.forward_journal,
-            "--split-mode", "none" if config.forward_journal.suffix == ".journal" else "host",
-        ],
-        pass_fds=(sockfd,),
-        sandbox=config.sandbox(
-            binary=bin,
-            mounts=[Mount(config.forward_journal.parent, config.forward_journal.parent)],
-        ),
-        user=config.forward_journal.parent.stat().st_uid if INVOKING_USER.invoked_as_root else None,
-        group=config.forward_journal.parent.stat().st_gid if INVOKING_USER.invoked_as_root else None,
-        # If all logs go into a single file, disable compact mode to allow for journal files exceeding 4G.
-        env={"SYSTEMD_JOURNAL_COMPACT": "0" if config.forward_journal.suffix == ".journal" else "1"},
-        foreground=False,
-    ) as (proc, innerpid):
-        allocate_scope(
-            config,
-            name=f"mkosi-journal-remote-{config.machine_or_name()}",
-            pid=innerpid,
-            description=f"mkosi systemd-journal-remote for {config.machine_or_name()}",
+    with tempfile.NamedTemporaryFile(mode="w", prefix="mkosi-journal-remote-config") as f:
+        # Make sure we capture all the logs by bumping the limits. We set MaxFileSize=4G because with the compact mode
+        # enabled the files cannot grow any larger anyway.
+        f.write(
+            textwrap.dedent(
+                f"""\
+                [Remote]
+                MaxUse=1T
+                KeepFree=1G
+                MaxFileSize=4G
+                MaxFiles={1 if config.forward_journal.suffix == ".journal" else 100}
+                """
+            )
         )
-        yield
-        kill(proc, innerpid, signal.SIGTERM)
+
+        f.flush()
+
+        with spawn(
+            [
+                bin,
+                "--output", config.forward_journal,
+                "--split-mode", "none" if config.forward_journal.suffix == ".journal" else "host",
+            ],
+            pass_fds=(sockfd,),
+            sandbox=config.sandbox(
+                binary=bin,
+                mounts=[
+                    Mount(config.forward_journal.parent, config.forward_journal.parent),
+                    Mount(f.name, "/etc/systemd/journal-remote.conf"),
+                ],
+            ),
+            user=config.forward_journal.parent.stat().st_uid if INVOKING_USER.invoked_as_root else None,
+            group=config.forward_journal.parent.stat().st_gid if INVOKING_USER.invoked_as_root else None,
+            foreground=False,
+        ) as (proc, innerpid):
+            allocate_scope(
+                config,
+                name=f"mkosi-journal-remote-{config.machine_or_name()}",
+                pid=innerpid,
+                description=f"mkosi systemd-journal-remote for {config.machine_or_name()}",
+            )
+            yield
+            kill(proc, innerpid, signal.SIGTERM)
 
 
 

diff --git a/mkosi/resources/mkosi.md b/mkosi/resources/mkosi.md
index 74303d4cff17a1d48a9df30fa4270d3311277a9d..b4c91e4341aae2e622e712047f565218d3731625 100644 (file)
--- a/mkosi/resources/mkosi.md
+++ b/mkosi/resources/mkosi.md
@@ -1916,6 +1916,11 @@ boolean argument: either `1`, `yes`, or `true` to enable, or `0`, `no`,
 : Note that systemd v256 or newer is required in the virtual machine for
   log forwarding to work.
 
+: Note that if a path with the `.journal` extension is given, the
+  journal size is limited to `4G`. Configure an output directory instead
+  of file if your workload produces more than `4G` worth of journal
+  data.
+
 ## Specifiers
 
 The current value of various settings can be accessed when parsing