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).
Client/Tool example (no dynamic flag url or config) sampleTool
Code as simple as
import (
"flag"
"os"
"fortio.org/cli"
"fortio.org/log"
)
func main() {
myFlag := flag.String("myflag", "default", "my flag")
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", *myFlag)
// 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:
-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
17:20:41 [I] Info test, -myflag is "default"
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 outputShort 'numeric' version (v skipped, useful for docker image tags etc)
% multicurl version
1.10.1You 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 -tag=no_tls_fallback.