// +build linux,cgo,!static_build,journald
package journald
// #include <sys/types.h>
// #include <sys/poll.h>
// #include <systemd/sd-journal.h>
// #include <errno.h>
// #include <stdio.h>
// #include <stdlib.h>
// #include <string.h>
// #include <time.h>
// #include <unistd.h>
//
//static int get_message(sd_journal *j, const char **msg, size_t *length, int *partial)
//{
// int rc;
// size_t plength;
// *msg = NULL;
// *length = 0;
// plength = strlen("CONTAINER_PARTIAL_MESSAGE=true");
// rc = sd_journal_get_data(j, "CONTAINER_PARTIAL_MESSAGE", (const void **) msg, length);
// *partial = ((rc == 0) && (*length == plength) && (memcmp(*msg, "CONTAINER_PARTIAL_MESSAGE=true", plength) == 0));
// rc = sd_journal_get_data(j, "MESSAGE", (const void **) msg, length);
// if (rc == 0) {
// if (*length > 8) {
// (*msg) += 8;
// *length -= 8;
// } else {
// *msg = NULL;
// *length = 0;
// rc = -ENOENT;
// }
// }
// return rc;
//}
//static int get_priority(sd_journal *j, int *priority)
//{
// const void *data;
// size_t i, length;
// int rc;
// *priority = -1;
// rc = sd_journal_get_data(j, "PRIORITY", &data, &length);
// if (rc == 0) {
// if ((length > 9) && (strncmp(data, "PRIORITY=", 9) == 0)) {
// *priority = 0;
// for (i = 9; i < length; i++) {
// *priority = *priority * 10 + ((const char *)data)[i] - '0';
// }
// if (length > 9) {
// rc = 0;
// }
// }
// }
// return rc;
//}
//static int is_attribute_field(const char *msg, size_t length)
//{
// static const struct known_field {
// const char *name;
// size_t length;
// } fields[] = {
// {"MESSAGE", sizeof("MESSAGE") - 1},
// {"MESSAGE_ID", sizeof("MESSAGE_ID") - 1},
// {"PRIORITY", sizeof("PRIORITY") - 1},
// {"CODE_FILE", sizeof("CODE_FILE") - 1},
// {"CODE_LINE", sizeof("CODE_LINE") - 1},
// {"CODE_FUNC", sizeof("CODE_FUNC") - 1},
// {"ERRNO", sizeof("ERRNO") - 1},
// {"SYSLOG_FACILITY", sizeof("SYSLOG_FACILITY") - 1},
// {"SYSLOG_IDENTIFIER", sizeof("SYSLOG_IDENTIFIER") - 1},
// {"SYSLOG_PID", sizeof("SYSLOG_PID") - 1},
// {"CONTAINER_NAME", sizeof("CONTAINER_NAME") - 1},
// {"CONTAINER_ID", sizeof("CONTAINER_ID") - 1},
// {"CONTAINER_ID_FULL", sizeof("CONTAINER_ID_FULL") - 1},
// {"CONTAINER_TAG", sizeof("CONTAINER_TAG") - 1},
// };
// unsigned int i;
// void *p;
// if ((length < 1) || (msg[0] == '_') || ((p = memchr(msg, '=', length)) == NULL)) {
// return -1;
// }
// length = ((const char *) p) - msg;
// for (i = 0; i < sizeof(fields) / sizeof(fields[0]); i++) {
// if ((fields[i].length == length) && (memcmp(fields[i].name, msg, length) == 0)) {
// return -1;
// }
// }
// return 0;
//}
//static int get_attribute_field(sd_journal *j, const char **msg, size_t *length)
//{
// int rc;
// *msg = NULL;
// *length = 0;
// while ((rc = sd_journal_enumerate_data(j, (const void **) msg, length)) > 0) {
// if (is_attribute_field(*msg, *length) == 0) {
// break;
// }
// rc = -ENOENT;
// }
// return rc;
//}
//static int wait_for_data_cancelable(sd_journal *j, int pipefd)
//{
// struct pollfd fds[2];
// uint64_t when = 0;
// int timeout, jevents, i;
// struct timespec ts;
// uint64_t now;
//
// memset(&fds, 0, sizeof(fds));
// fds[0].fd = pipefd;
// fds[0].events = POLLHUP;
// fds[1].fd = sd_journal_get_fd(j);
// if (fds[1].fd < 0) {
// return fds[1].fd;
// }
//
// do {
// jevents = sd_journal_get_events(j);
// if (jevents < 0) {
// return jevents;
// }
// fds[1].events = jevents;
// sd_journal_get_timeout(j, &when);
// if (when == -1) {
// timeout = -1;
// } else {
// clock_gettime(CLOCK_MONOTONIC, &ts);
// now = (uint64_t) ts.tv_sec * 1000000 + ts.tv_nsec / 1000;
// timeout = when > now ? (int) ((when - now + 999) / 1000) : 0;
// }
// i = poll(fds, 2, timeout);
// if ((i == -1) && (errno != EINTR)) {
// /* An unexpected error. */
// return (errno != 0) ? -errno : -EINTR;
// }
// if (fds[0].revents & POLLHUP) {
// /* The close notification pipe was closed. */
// return 0;
// }
// if (sd_journal_process(j) == SD_JOURNAL_APPEND) {
// /* Data, which we might care about, was appended. */
// return 1;
// }
// } while ((fds[0].revents & POLLHUP) == 0);
// return 0;
//}
import "C"
import (
"fmt"
"strings"
"time"
"unsafe"
"github.com/coreos/go-systemd/journal"
"github.com/docker/docker/api/types/backend"
"github.com/docker/docker/daemon/logger"
"github.com/sirupsen/logrus"
)
func (s *journald) Close() error {
s.mu.Lock()
s.closed = true
for reader := range s.readers.readers {
reader.Close()
}
s.mu.Unlock()
return nil
}
func (s *journald) drainJournal(logWatcher *logger.LogWatcher, config logger.ReadConfig, j *C.sd_journal, oldCursor *C.char) *C.char {
var msg, data, cursor *C.char
var length C.size_t
var stamp C.uint64_t
var priority, partial C.int
// Walk the journal from here forward until we run out of new entries.
drain:
for {
// Try not to send a given entry twice.
if oldCursor != nil {
for C.sd_journal_test_cursor(j, oldCursor) > 0 {
if C.sd_journal_next(j) <= 0 {
break drain
}
}
}
// Read and send the logged message, if there is one to read.
i := C.get_message(j, &msg, &length, &partial)
if i != -C.ENOENT && i != -C.EADDRNOTAVAIL {
// Read the entry's timestamp.
if C.sd_journal_get_realtime_usec(j, &stamp) != 0 {
break
}
// Set up the time and text of the entry.
timestamp := time.Unix(int64(stamp)/1000000, (int64(stamp)%1000000)*1000)
line := C.GoBytes(unsafe.Pointer(msg), C.int(length))
if partial == 0 {
line = append(line, "\n"...)
}
// Recover the stream name by mapping
// from the journal priority back to
// the stream that we would have
// assigned that value.
source := ""
if C.get_priority(j, &priority) != 0 {
source = ""
} else if priority == C.int(journal.PriErr) {
source = "stderr"
} else if priority == C.int(journal.PriInfo) {
source = "stdout"
}
// Retrieve the values of any variables we're adding to the journal.
var attrs []backend.LogAttr
C.sd_journal_restart_data(j)
for C.get_attribute_field(j, &data, &length) > C.int(0) {
kv := strings.SplitN(C.GoStringN(data, C.int(length)), "=", 2)
attrs = append(attrs, backend.LogAttr{Key: kv[0], Value: kv[1]})
}
// Send the log message.
logWatcher.Msg <- &logger.Message{
Line: line,
Source: source,
Timestamp: timestamp.In(time.UTC),
Attrs: attrs,
}
}
// If we're at the end of the journal, we're done (for now).
if C.sd_journal_next(j) <= 0 {
break
}
}
// free(NULL) is safe
C.free(unsafe.Pointer(oldCursor))
if C.sd_journal_get_cursor(j, &cursor) != 0 {
// ensure that we won't be freeing an address that's invalid
cursor = nil
}
return cursor
}
func (s *journald) followJournal(logWatcher *logger.LogWatcher, config logger.ReadConfig, j *C.sd_journal, pfd [2]C.int, cursor *C.char) *C.char {
s.mu.Lock()
s.readers.readers[logWatcher] = logWatcher
if s.closed {
// the journald Logger is closed, presumably because the container has been
// reset. So we shouldn't follow, because we'll never be woken up. But we
// should make one more drainJournal call to be sure we've got all the logs.
// Close pfd[1] so that one drainJournal happens, then cleanup, then return.
C.close(pfd[1])
}
s.mu.Unlock()
newCursor := make(chan *C.char)
go func() {
for {
// Keep copying journal data out until we're notified to stop
// or we hit an error.
status := C.wait_for_data_cancelable(j, pfd[0])
if status < 0 {
cerrstr := C.strerror(C.int(-status))
errstr := C.GoString(cerrstr)
fmtstr := "error %q while attempting to follow journal for container %q"
logrus.Errorf(fmtstr, errstr, s.vars["CONTAINER_ID_FULL"])
break
}
cursor = s.drainJournal(logWatcher, config, j, cursor)
if status != 1 {
// We were notified to stop
break
}
}
// Clean up.
C.close(pfd[0])
s.mu.Lock()
delete(s.readers.readers, logWatcher)
s.mu.Unlock()
close(logWatcher.Msg)
newCursor <- cursor
}()
// Wait until we're told to stop.
select {
case cursor = <-newCursor:
case <-logWatcher.WatchClose():
// Notify the other goroutine that its work is done.
C.close(pfd[1])
cursor = <-newCursor
}
return cursor
}
func (s *journald) readLogs(logWatcher *logger.LogWatcher, config logger.ReadConfig) {
var j *C.sd_journal
var cmatch, cursor *C.char
var stamp C.uint64_t
var sinceUnixMicro uint64
var pipes [2]C.int
// Get a handle to the journal.
rc := C.sd_journal_open(&j, C.int(0))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error opening journal")
close(logWatcher.Msg)
return
}
// If we end up following the log, we can set the journal context
// pointer and the channel pointer to nil so that we won't close them
// here, potentially while the goroutine that uses them is still
// running. Otherwise, close them when we return from this function.
following := false
defer func(pfollowing *bool) {
if !*pfollowing {
close(logWatcher.Msg)
}
C.sd_journal_close(j)
}(&following)
// Remove limits on the size of data items that we'll retrieve.
rc = C.sd_journal_set_data_threshold(j, C.size_t(0))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error setting journal data threshold")
return
}
// Add a match to have the library do the searching for us.
cmatch = C.CString("CONTAINER_ID_FULL=" + s.vars["CONTAINER_ID_FULL"])
defer C.free(unsafe.Pointer(cmatch))
rc = C.sd_journal_add_match(j, unsafe.Pointer(cmatch), C.strlen(cmatch))
if rc != 0 {
logWatcher.Err <- fmt.Errorf("error setting journal match")
return
}
// If we have a cutoff time, convert it to Unix time once.
if !config.Since.IsZero() {
nano := config.Since.UnixNano()
sinceUnixMicro = uint64(nano / 1000)
}
if config.Tail > 0 {
lines := config.Tail
// Start at the end of the journal.
if C.sd_journal_seek_tail(j) < 0 {
logWatcher.Err <- fmt.Errorf("error seeking to end of journal")
return
}
if C.sd_journal_previous(j) < 0 {
logWatcher.Err <- fmt.Errorf("error backtracking to previous journal entry")
return
}
// Walk backward.
for lines > 0 {
// Stop if the entry time is before our cutoff.
// We'll need the entry time if it isn't, so go
// ahead and parse it now.
if C.sd_journal_get_realtime_usec(j, &stamp) != 0 {
break
} else {
// Compare the timestamp on the entry
// to our threshold value.
if sinceUnixMicro != 0 && sinceUnixMicro > uint64(stamp) {
break
}
}
lines--
// If we're at the start of the journal, or
// don't need to back up past any more entries,
// stop.
if lines == 0 || C.sd_journal_previous(j) <= 0 {
break
}
}
} else {
// Start at the beginning of the journal.
if C.sd_journal_seek_head(j) < 0 {
logWatcher.Err <- fmt.Errorf("error seeking to start of journal")
return
}
// If we have a cutoff date, fast-forward to it.
if sinceUnixMicro != 0 && C.sd_journal_seek_realtime_usec(j, C.uint64_t(sinceUnixMicro)) != 0 {
logWatcher.Err <- fmt.Errorf("error seeking to start time in journal")
return
}
if C.sd_journal_next(j) < 0 {
logWatcher.Err <- fmt.Errorf("error skipping to next journal entry")
return
}
}
cursor = s.drainJournal(logWatcher, config, j, nil)
if config.Follow {
// Allocate a descriptor for following the journal, if we'll
// need one. Do it here so that we can report if it fails.
if fd := C.sd_journal_get_fd(j); fd < C.int(0) {
logWatcher.Err <- fmt.Errorf("error opening journald follow descriptor: %q", C.GoString(C.strerror(-fd)))
} else {
// Create a pipe that we can poll at the same time as
// the journald descriptor.
if C.pipe(&pipes[0]) == C.int(-1) {
logWatcher.Err <- fmt.Errorf("error opening journald close notification pipe")
} else {
cursor = s.followJournal(logWatcher, config, j, pipes, cursor)
// Let followJournal handle freeing the journal context
// object and closing the channel.
following = true
}
}
}
C.free(unsafe.Pointer(cursor))
return
}
func (s *journald) ReadLogs(config logger.ReadConfig) *logger.LogWatcher {
logWatcher := logger.NewLogWatcher()
go s.readLogs(logWatcher, config)
return logWatcher
}