m/pkg/logtree/unraw: implement

This is another part of the generic external leveled log ingestion
mechanism. This parts takes care of ingesting external data either by
exposing an io.Writer or a named pipe on the filesystem from which
external logs are parsed and then inejcted into the logtree.

Change-Id: Ie2263496ca4d50220abdd8e4d37a35730d127319
Reviewed-on: https://review.monogon.dev/c/monogon/+/208
Reviewed-by: Leopold Schabel <leo@nexantic.com>
diff --git a/metropolis/pkg/logtree/unraw/unraw_test.go b/metropolis/pkg/logtree/unraw/unraw_test.go
new file mode 100644
index 0000000..faf7895
--- /dev/null
+++ b/metropolis/pkg/logtree/unraw/unraw_test.go
@@ -0,0 +1,112 @@
+package unraw
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"source.monogon.dev/metropolis/pkg/logbuffer"
+	"source.monogon.dev/metropolis/pkg/logtree"
+	"source.monogon.dev/metropolis/pkg/supervisor"
+)
+
+func testParser(l *logbuffer.Line, w LeveledWriter) {
+	w(&logtree.ExternalLeveledPayload{
+		Message: l.Data,
+	})
+}
+
+func TestNamedPipeReader(t *testing.T) {
+	dir, err := ioutil.TempDir("", "metropolis-test-named-pipe-reader")
+	if err != nil {
+		t.Fatalf("could not create tempdir: %v", err)
+	}
+	//defer os.RemoveAll(dir)
+	fifoPath := dir + "/fifo"
+
+	// Start named pipe reader.
+	started := make(chan struct{})
+	stop, lt := supervisor.TestHarness(t, func(ctx context.Context) error {
+		converter := Converter{
+			Parser:        testParser,
+			LeveledLogger: supervisor.Logger(ctx),
+		}
+
+		r, err := converter.NamedPipeReader(fifoPath)
+		if err != nil {
+			return fmt.Errorf("could not create pipe reader: %w", err)
+		}
+		close(started)
+		return r(ctx)
+	})
+
+	// Wait until NamedPipeReader returns to make sure the fifo was created..
+	<-started
+
+	// Start reading all logs.
+	reader, err := lt.Read("root", logtree.WithChildren(), logtree.WithStream())
+	if err != nil {
+		t.Fatalf("could not get logtree reader: %v", err)
+	}
+	defer reader.Close()
+
+	// Write two lines to the fifo.
+	f, err := os.OpenFile(fifoPath, os.O_RDWR, 0)
+	if err != nil {
+		t.Fatalf("could not open fifo: %v", err)
+	}
+	fmt.Fprintf(f, "foo\nbar\n")
+	f.Close()
+
+	// Expect lines to end up in logtree.
+	if got, want := (<-reader.Stream).Leveled.MessagesJoined(), "foo"; want != got {
+		t.Errorf("expected first message to be %q, got %q", want, got)
+	}
+	if got, want := (<-reader.Stream).Leveled.MessagesJoined(), "bar"; want != got {
+		t.Errorf("expected second message to be %q, got %q", want, got)
+	}
+
+	// Fully restart the entire hypervisor and pipe reader, redo test, things
+	// should continue to work.
+	stop()
+
+	started = make(chan struct{})
+	stop, lt = supervisor.TestHarness(t, func(ctx context.Context) error {
+		converter := Converter{
+			Parser:        testParser,
+			LeveledLogger: supervisor.Logger(ctx),
+		}
+
+		r, err := converter.NamedPipeReader(fifoPath)
+		if err != nil {
+			return fmt.Errorf("could not create pipe reader: %w", err)
+		}
+		close(started)
+		return r(ctx)
+	})
+
+	// Start reading all logs.
+	reader, err = lt.Read("root", logtree.WithChildren(), logtree.WithStream())
+	if err != nil {
+		t.Fatalf("could not get logtree reader: %v", err)
+	}
+	defer reader.Close()
+
+	<-started
+
+	// Write line to the fifo.
+	// Write two lines to the fifo.
+	f, err = os.OpenFile(fifoPath, os.O_RDWR, 0)
+	if err != nil {
+		t.Fatalf("could not open fifo: %v", err)
+	}
+	fmt.Fprintf(f, "baz\n")
+	f.Close()
+
+	// Expect lines to end up in logtree.
+	if got, want := (<-reader.Stream).Leveled.MessagesJoined(), "baz"; want != got {
+		t.Errorf("expected first message to be %q, got %q", want, got)
+	}
+}