update vendor

Signed-off-by: Roland.Ma <rolandma@yunify.com>
This commit is contained in:
Roland.Ma
2021-08-11 07:10:14 +00:00
parent a18f72b565
commit ea8f47c73a
2901 changed files with 269317 additions and 43103 deletions

View File

@@ -1,9 +1,9 @@
# A more minimal logging API for Go
Before you consider this package, please read [this blog post by the inimitable
Dave Cheney](http://dave.cheney.net/2015/11/05/lets-talk-about-logging). I
really appreciate what he has to say, and it largely aligns with my own
experiences. Too many choices of levels means inconsistent logs.
Before you consider this package, please read [this blog post by the
inimitable Dave Cheney][warning-makes-no-sense]. I really appreciate what
he has to say, and it largely aligns with my own experiences. Too many
choices of levels means inconsistent logs.
This package offers a purely abstract interface, based on these ideas but with
a few twists. Code can depend on just this interface and have the actual
@@ -31,6 +31,153 @@ may feel very similar, but the primary difference is the lack of semantics.
Because verbosity is a numerical value, it's safe to assume that an app running
with higher verbosity means more (and less important) logs will be generated.
This is a BETA grade API. I have implemented it for
[glog](https://godoc.org/github.com/golang/glog). Until there is a significant
2nd implementation, I don't really know how it will change.
This is a BETA grade API.
There are implementations for the following logging libraries:
- **github.com/google/glog**: [glogr](https://github.com/go-logr/glogr)
- **k8s.io/klog**: [klogr](https://git.k8s.io/klog/klogr)
- **go.uber.org/zap**: [zapr](https://github.com/go-logr/zapr)
- **log** (the Go standard library logger):
[stdr](https://github.com/go-logr/stdr)
- **github.com/sirupsen/logrus**: [logrusr](https://github.com/bombsimon/logrusr)
- **github.com/wojas/genericr**: [genericr](https://github.com/wojas/genericr) (makes it easy to implement your own backend)
- **logfmt** (Heroku style [logging](https://www.brandur.org/logfmt)): [logfmtr](https://github.com/iand/logfmtr)
# FAQ
## Conceptual
## Why structured logging?
- **Structured logs are more easily queriable**: Since you've got
key-value pairs, it's much easier to query your structured logs for
particular values by filtering on the contents of a particular key --
think searching request logs for error codes, Kubernetes reconcilers for
the name and namespace of the reconciled object, etc
- **Structured logging makes it easier to have cross-referencable logs**:
Similarly to searchability, if you maintain conventions around your
keys, it becomes easy to gather all log lines related to a particular
concept.
- **Structured logs allow better dimensions of filtering**: if you have
structure to your logs, you've got more precise control over how much
information is logged -- you might choose in a particular configuration
to log certain keys but not others, only log lines where a certain key
matches a certain value, etc, instead of just having v-levels and names
to key off of.
- **Structured logs better represent structured data**: sometimes, the
data that you want to log is inherently structured (think tuple-link
objects). Structured logs allow you to preserve that structure when
outputting.
## Why V-levels?
**V-levels give operators an easy way to control the chattiness of log
operations**. V-levels provide a way for a given package to distinguish
the relative importance or verbosity of a given log message. Then, if
a particular logger or package is logging too many messages, the user
of the package can simply change the v-levels for that library.
## Why not more named levels, like Warning?
Read [Dave Cheney's post][warning-makes-no-sense]. Then read [Differences
from Dave's ideas](#differences-from-daves-ideas).
## Why not allow format strings, too?
**Format strings negate many of the benefits of structured logs**:
- They're not easily searchable without resorting to fuzzy searching,
regular expressions, etc
- They don't store structured data well, since contents are flattened into
a string
- They're not cross-referencable
- They don't compress easily, since the message is not constant
(unless you turn positional parameters into key-value pairs with numerical
keys, at which point you've gotten key-value logging with meaningless
keys)
## Practical
## Why key-value pairs, and not a map?
Key-value pairs are *much* easier to optimize, especially around
allocations. Zap (a structured logger that inspired logr's interface) has
[performance measurements](https://github.com/uber-go/zap#performance)
that show this quite nicely.
While the interface ends up being a little less obvious, you get
potentially better performance, plus avoid making users type
`map[string]string{}` every time they want to log.
## What if my V-levels differ between libraries?
That's fine. Control your V-levels on a per-logger basis, and use the
`WithName` function to pass different loggers to different libraries.
Generally, you should take care to ensure that you have relatively
consistent V-levels within a given logger, however, as this makes deciding
on what verbosity of logs to request easier.
## But I *really* want to use a format string!
That's not actually a question. Assuming your question is "how do
I convert my mental model of logging with format strings to logging with
constant messages":
1. figure out what the error actually is, as you'd write in a TL;DR style,
and use that as a message
2. For every place you'd write a format specifier, look to the word before
it, and add that as a key value pair
For instance, consider the following examples (all taken from spots in the
Kubernetes codebase):
- `klog.V(4).Infof("Client is returning errors: code %v, error %v",
responseCode, err)` becomes `logger.Error(err, "client returned an
error", "code", responseCode)`
- `klog.V(4).Infof("Got a Retry-After %ds response for attempt %d to %v",
seconds, retries, url)` becomes `logger.V(4).Info("got a retry-after
response when requesting url", "attempt", retries, "after
seconds", seconds, "url", url)`
If you *really* must use a format string, place it as a key value, and
call `fmt.Sprintf` yourself -- for instance, `log.Printf("unable to
reflect over type %T")` becomes `logger.Info("unable to reflect over
type", "type", fmt.Sprintf("%T"))`. In general though, the cases where
this is necessary should be few and far between.
## How do I choose my V-levels?
This is basically the only hard constraint: increase V-levels to denote
more verbose or more debug-y logs.
Otherwise, you can start out with `0` as "you always want to see this",
`1` as "common logging that you might *possibly* want to turn off", and
`10` as "I would like to performance-test your log collection stack".
Then gradually choose levels in between as you need them, working your way
down from 10 (for debug and trace style logs) and up from 1 (for chattier
info-type logs).
## How do I choose my keys
- make your keys human-readable
- constant keys are generally a good idea
- be consistent across your codebase
- keys should naturally match parts of the message string
While key names are mostly unrestricted (and spaces are acceptable),
it's generally a good idea to stick to printable ascii characters, or at
least match the general character set of your log lines.
[warning-makes-no-sense]: http://dave.cheney.net/2015/11/05/lets-talk-about-logging