diff options
Diffstat (limited to 'srv/cfg')
| -rw-r--r-- | srv/cfg/cfg.go | 200 | ||||
| -rw-r--r-- | srv/cfg/cfg_test.go | 46 |
2 files changed, 0 insertions, 246 deletions
diff --git a/srv/cfg/cfg.go b/srv/cfg/cfg.go deleted file mode 100644 index 8513e16..0000000 --- a/srv/cfg/cfg.go +++ /dev/null @@ -1,200 +0,0 @@ -// Package cfg implements a simple wrapper around go's flag package, in order to -// implement initialization hooks. -package cfg - -import ( - "context" - "flag" - "fmt" - "os" - "strconv" - "strings" -) - -// Cfger is a component which can be used with Cfg to setup its initialization. -type Cfger interface { - SetupCfg(*Cfg) -} - -// Params are used to initialize a Cfg instance. -type Params struct { - - // Args are the command line arguments, excluding the command-name. - // - // Defaults to os.Args[1:] - Args []string - - // Env is the process's environment variables. - // - // Defaults to the real environment variables. - Env map[string]string - - // EnvPrefix indicates a string to prefix to all environment variable names - // that Cfg will read. Will be automatically suffixed with a "_" if given. - EnvPrefix string -} - -func (p Params) withDefaults() Params { - - if p.Args == nil { - p.Args = os.Args[1:] - } - - if p.Env == nil { - - p.Env = map[string]string{} - - for _, envVar := range os.Environ() { - - parts := strings.SplitN(envVar, "=", 2) - - if len(parts) < 2 { - panic(fmt.Sprintf("envVar %q returned from os.Environ() somehow", envVar)) - } - - p.Env[parts[0]] = parts[1] - } - } - - if p.EnvPrefix != "" { - p.EnvPrefix = strings.TrimSuffix(p.EnvPrefix, "_") + "_" - } - - return p -} - -// Cfg is a wrapper around the stdlib's FlagSet and a set of initialization -// hooks. -type Cfg struct { - params Params - flagSet *flag.FlagSet - - hooks []func(ctx context.Context) error -} - -// New initializes and returns a new instance of *Cfg. -func New(params Params) *Cfg { - - params = params.withDefaults() - - return &Cfg{ - params: params, - flagSet: flag.NewFlagSet("", flag.ExitOnError), - } -} - -// OnInit appends the given callback to the sequence of hooks which will run on -// a call to Init. -func (c *Cfg) OnInit(cb func(context.Context) error) { - c.hooks = append(c.hooks, cb) -} - -// Init runs all hooks registered using OnInit, in the same order OnInit was -// called. If one returns an error that error is returned and no further hooks -// are run. -func (c *Cfg) Init(ctx context.Context) error { - if err := c.flagSet.Parse(c.params.Args); err != nil { - return err - } - - for _, h := range c.hooks { - if err := h(ctx); err != nil { - return err - } - } - - return nil -} - -func (c *Cfg) envifyName(name string) string { - name = c.params.EnvPrefix + name - name = strings.Replace(name, "-", "_", -1) - name = strings.ToUpper(name) - return name -} - -func envifyUsage(envName, usage string) string { - return fmt.Sprintf("%s (overrides %s)", usage, envName) -} - -// StringVar is equivalent to flag.FlagSet's StringVar method, but will -// additionally set up an environment variable for the parameter. -func (c *Cfg) StringVar(p *string, name, value, usage string) { - - envName := c.envifyName(name) - - c.flagSet.StringVar(p, name, value, envifyUsage(envName, usage)) - - if val := c.params.Env[envName]; val != "" { - *p = val - } -} - -// String is equivalent to flag.FlagSet's String method, but will additionally -// set up an environment variable for the parameter. -func (c *Cfg) String(name, value, usage string) *string { - p := new(string) - c.StringVar(p, name, value, usage) - return p -} - -// IntVar is equivalent to flag.FlagSet's IntVar method, but will additionally -// set up an environment variable for the parameter. -func (c *Cfg) IntVar(p *int, name string, value int, usage string) { - - envName := c.envifyName(name) - - c.flagSet.IntVar(p, name, value, envifyUsage(envName, usage)) - - // if we can't parse the envvar now then just hold onto the error until - // Init, otherwise we'd have to panic here and that'd be ugly. - var err error - - if valStr := c.params.Env[envName]; valStr != "" { - - var val int - val, err = strconv.Atoi(valStr) - - if err != nil { - err = fmt.Errorf( - "parsing envvar %q with value %q: %w", - envName, valStr, err, - ) - - } else { - *p = val - } - } - - c.OnInit(func(context.Context) error { return err }) -} - -// Int is equivalent to flag.FlagSet's Int method, but will additionally set up -// an environment variable for the parameter. -func (c *Cfg) Int(name string, value int, usage string) *int { - p := new(int) - c.IntVar(p, name, value, usage) - return p -} - -// SubCmd should be called _after_ Init. Init will have consumed all arguments -// up until the first non-flag argument. This non-flag argument is a -// sub-command, and is returned by this method. This method also resets Cfg's -// internal state so that new options can be added to it. -// -// If there is no sub-command following the initial set of flags then this will -// return empty string. -func (c *Cfg) SubCmd() string { - c.params.Args = c.flagSet.Args() - if len(c.params.Args) == 0 { - return "" - } - - subCmd := c.params.Args[0] - - c.flagSet = flag.NewFlagSet(subCmd, flag.ExitOnError) - c.hooks = nil - c.params.Args = c.params.Args[1:] - - return subCmd -} diff --git a/srv/cfg/cfg_test.go b/srv/cfg/cfg_test.go deleted file mode 100644 index 7ccf94a..0000000 --- a/srv/cfg/cfg_test.go +++ /dev/null @@ -1,46 +0,0 @@ -package cfg - -import ( - "context" - "testing" - - "github.com/stretchr/testify/assert" -) - -func TestStringVar(t *testing.T) { - - cfg := New(Params{ - Args: []string{"--foo=CLI"}, - Env: map[string]string{"FOO": "ENV", "BAR": "ENV"}, - }) - - var foo, bar, baz string - - cfg.StringVar(&foo, "foo", "DEF", "") - cfg.StringVar(&bar, "bar", "DEF", "") - cfg.StringVar(&baz, "baz", "DEF", "") - - assert.NoError(t, cfg.Init(context.Background())) - assert.Equal(t, "CLI", foo) - assert.Equal(t, "ENV", bar) - assert.Equal(t, "DEF", baz) -} - -func TestIntVar(t *testing.T) { - - cfg := New(Params{ - Args: []string{"--foo=111"}, - Env: map[string]string{"FOO": "222", "BAR": "222"}, - }) - - var foo, bar, baz int - - cfg.IntVar(&foo, "foo", 333, "") - cfg.IntVar(&bar, "bar", 333, "") - cfg.IntVar(&baz, "baz", 333, "") - - assert.NoError(t, cfg.Init(context.Background())) - assert.Equal(t, 111, foo) - assert.Equal(t, 222, bar) - assert.Equal(t, 333, baz) -} |