This commit introduces a new tracing library, that replaces
golang.org/x/net/trace, and supports (amongts other thing) nested
traces.
This is a minimal change, future patches will make use of the new
functionality.
By default, golang.org/x/net/trace currently only allows the tracing
pages to be seen from localhost.
This restriction can be confusing for people accessing the monitoring
server remotely, and adds no value in our environment.
The monitoring server already exports very sensitive information, and
must be enabled with care, and is not on by default. This is well
documented.
This patch removes the restriction, making all the monitoring pages
equally accessible.
This patch adds a missing docstrings for exported identifiers, and
adjust some of the existing ones to match the standard style.
In some cases, the identifiers were un-exported after noticing they had
no external users.
Besides improving documentation, it also reduces the linter noise
significantly.
glog works fine and has great features, but it does not play along well
with systemd or standard log rotators (as it does the rotation itself).
So this patch replaces glog with a new logging module "log", which by
default logs to stderr, in a systemd-friendly manner.
Logging to files or syslog is still supported.
Errors can contain newlines, in particular this is common in messages
returned by remote SMTP servers.
This patch quotes them before logging, they don't interfere with the
log. Note the tracer itself can handle this just fine.
The default for max events is 10, which is a bit short for a normal SMTP
exchange. Expand it to 30 which should be large enough to keep most of
the traces.
We don't want to write debug messages to the log, but having them in
traces is always useful.
The traces are volatile and self-cleaning so the additional volume
should not cause any problems, and helps troubleshooting.
While at it, fix the depth constant when logging.
This patch reviews various debug and informational messages, making more
uniform use of tracing, and extends the monitoring http server with
useful information like an index and a queue dump.
This patch introduces the couriers, which the queue uses to deliver mail.
We have a local courier (using procmail), a remote courier (uses SMTP), and a
router courier that decides which of the two to use based on a list of local
domains.
There are still a few things pending, but they all have their basic
functionality working and tested.
