gem-hunter
Language: Go
Reduce boiler plate needed on each new Golang main functions (Command Line Interface) for both tool and servers
Reduce boiler plate needed on each new Golang main functions (Command Line Interface) for both tools and servers (use fortio.org/scli ServerMain() for server)
It abstracts the repetitive parts of a main() command line tool, flag parsing, usage, etc...
You can see real use example in a tool like multicurl or a server like proxy.
It also supports (sub)commands style (where there is a word/command before the flags and remaining arguments, fortio uses that mode).
If you have durations in flags, do use the 0 dependencies fortio.org/duration Flag along this package.
Client/Tool example (no dynamic flag url or config) sampleTool
Code as simple as
import ( "flag" "os" "fortio.org/cli" "fortio.org/duration" "fortio.org/log" ) func main() { myFlag := flag.String("myflag", "default", "my flag") durationExample := duration.Flag("duration", 1*duration.Day, "example of `duration` flag with days support") cli.MinArgs = 2 cli.MaxArgs = 4 cli.Main() // Will have either called cli.ExitFunction or everything is valid // Next line output won't show when passed -quiet log.Infof("Info test, -myflag is %q and duration is %v", *myFlag, duration.Duration(*durationExample)) // This always shows log.Printf("Hello world, version %s, args %v", cli.ShortVersion, flag.Args()) // This shows and is colorized and structured, unless loglevel is set to critical. log.S(log.Error, "Error test", log.Str("myflag", *myFlag), log.Attr("num_args", len(flag.Args())), log.Attr("args", flag.Args())) }
$ sampleTool a
sampleTool 1.2.0 usage:
sampleTool [flags] arg1 arg2 [arg3...arg4]
or 1 of the special arguments
sampleTool {help|version|buildinfo}
flags:
-duration duration
example of duration flag with days support (default 1d)
-logger-force-color
Force color output even if stderr isn't a terminal
-logger-no-color
Prevent colorized output even if stderr is a terminal
-loglevel level
log level, one of [Debug Verbose Info Warning Error Critical Fatal] (default Info)
-myflag string
my flag (default "default")
-quiet
Quiet mode, sets loglevel to Error (quietly) to reduces the output
At least 2 arguments expected, got 1Since v1.3, the above is colorized on a terminal and looks like this:
or normal case:
Old style, no colors:
$ sampleTool -logger-no-color a b -duration 1w3h 17:20:41 [I] Info test, -myflag is "default" and duration is 1w3h 17:20:41 Hello world, version dev, args [a b] 17:20:41 [E] Error test, myflag="default", num_args="2", args="[a b]"
e.g
% go install github.com/fortio/multicurl@latest go: downloading github.com/fortio/multicurl v1.10.1 % multicurl buildinfo 1.10.1 h1:h9yM3XplwG7JWtVaSS0eJPiDmCJfnxvj3w+yoAMWMo4= go1.19.6 arm64 darwin go go1.19.6 path github.com/fortio/multicurl mod github.com/fortio/multicurl v1.10.1 h1:h9yM3XplwG7JWtVaSS0eJPiDmCJfnxvj3w+yoAMWMo4= dep fortio.org/cli v0.6.1 h1:V9L6ly4oz4fJjeQ5745FulIMsFAwFZvLPSUN+cKUrKk= dep fortio.org/log v1.2.2 h1:vs42JjNwiqbMbacittZjJE9+oi72Za6aekML9gKmILg= dep fortio.org/version v1.0.2 h1:8NwxdX58aoeKx7T5xAPO0xlUu1Hpk42nRz5s6e6eKZ0= build -compiler=gc build CGO_ENABLED=1 build CGO_CFLAGS= build CGO_CPPFLAGS= build CGO_CXXFLAGS= build CGO_LDFLAGS= build GOARCH=arm64 build GOOS=darwin
% multicurl help Fortio multicurl 1.10.1 usage: multicurl [flags] url or 1 of the special arguments multicurl {help|version|buildinfo} flags: [...] -logger-force-color Force color output even if stderr isn't a terminal -logger-no-color Prevent colorized output even if stderr is a terminal -loglevel level log level, one of [Debug Verbose Info Warning Error Critical Fatal] (default Info) -quiet Quiet mode, sets loglevel to Error (quietly) to reduces the output
Short 'numeric' version (v skipped, useful for docker image tags etc)
% multicurl version 1.10.1
You should always try to use FROM scratch Docker images when possible,
it's one of the strength of go.
Using this fortio.org/cli as a base makes it work for outcalls to internet valid TLS certs (e.g. https).
It does this by defaulting to the bundle provided by golang.org/x/crypto/x509roots/fallback automatically.
See https://github.com/fortio/multicurl for a good example.
If you do not want this behavior, build using -tags no_tls_fallback.
If you application doesn't do http request/response logging at all, use -tags no_http or -tags no_net (that one will also imply no_tls_fallback) and save 1.6 Mbytes in your binary's size (because the linker isn't smart enough to see net/http isn't actually used) (1.1Mbytes for log's no_http and 530k from the no_tls_fallback)
And, if you don't need any of the advanced JSON logging (which is quite likely with a cli), use -tags no_json the logger will still produce json structured logging just not as advanced if what you log are deep structures - this saves another 130k or so.
These tags are from fortio.org/log v1.14 and later
In summary: for smallest pure local cli binaries using this package:
CGO_ENABLE=0 go build -trimpath -ldflags="-w -s" -tags no_net,no_json .
saves ~1.7Mbytes in total (a basic cli dependending on this package will then only be about 300k more as an hello world yet include color help, buildinfo, version, logging etc)