From 4f01edb9230f58ff84b0dd892c931ec8ac9aad55 Mon Sep 17 00:00:00 2001 From: Brian Picciano Date: Tue, 13 Sep 2022 12:56:08 +0200 Subject: move src out of srv, clean up default.nix and Makefile --- src/cfg/cfg.go | 255 +++++++++++++++++++++++++++++++++++++++++++++++ src/cfg/cfg_test.go | 67 +++++++++++++ src/cfg/data_dir.go | 74 ++++++++++++++ src/cfg/mediocre_blog.go | 9 ++ 4 files changed, 405 insertions(+) create mode 100644 src/cfg/cfg.go create mode 100644 src/cfg/cfg_test.go create mode 100644 src/cfg/data_dir.go create mode 100644 src/cfg/mediocre_blog.go (limited to 'src/cfg') diff --git a/src/cfg/cfg.go b/src/cfg/cfg.go new file mode 100644 index 0000000..d87c45b --- /dev/null +++ b/src/cfg/cfg.go @@ -0,0 +1,255 @@ +// 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 + } +} + +// Args returns a pointer which will be filled with the process's positional +// arguments after Init is called. The positional arguments are all CLI +// arguments starting with the first non-flag argument. +// +// The usage argument should describe what these arguments are, and its notation +// should indicate if they are optional or variadic. For example: +// +// // optional variadic +// "[names...]" +// +// // required single args +// " " +// +// // Mixed +// " [baz] [other...]" +// +func (c *Cfg) Args(usage string) *[]string { + + args := new([]string) + + c.flagSet.Usage = func() { + fmt.Fprintf(os.Stderr, "USAGE [flags...] %s\n", usage) + fmt.Fprintf(os.Stderr, "\nFLAGS\n\n") + c.flagSet.PrintDefaults() + } + + c.OnInit(func(ctx context.Context) error { + *args = c.flagSet.Args() + return nil + }) + + return args +} + +// 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 +} + +// BoolVar is equivalent to flag.FlagSet's BoolVar method, but will additionally +// set up an environment variable for the parameter. +func (c *Cfg) BoolVar(p *bool, name string, value bool, usage string) { + + envName := c.envifyName(name) + + c.flagSet.BoolVar(p, name, value, envifyUsage(envName, usage)) + + if valStr := c.params.Env[envName]; valStr != "" { + *p = valStr != "" && valStr != "0" && valStr != "false" + } +} + +// Bool is equivalent to flag.FlagSet's Bool method, but will additionally set +// up an environment variable for the parameter. +func (c *Cfg) Bool(name string, value bool, usage string) *bool { + p := new(bool) + c.BoolVar(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/src/cfg/cfg_test.go b/src/cfg/cfg_test.go new file mode 100644 index 0000000..8266c89 --- /dev/null +++ b/src/cfg/cfg_test.go @@ -0,0 +1,67 @@ +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) +} + +func TestBoolVar(t *testing.T) { + + cfg := New(Params{ + Args: []string{"--foo=1"}, + Env: map[string]string{"FOO": "0", "BAR": "anything", "BIZ": "0"}, + }) + + var foo, bar, baz, biz bool + + cfg.BoolVar(&foo, "foo", false, "") + cfg.BoolVar(&bar, "bar", false, "") + cfg.BoolVar(&baz, "baz", false, "") + cfg.BoolVar(&biz, "biz", true, "") + + assert.NoError(t, cfg.Init(context.Background())) + assert.Equal(t, true, foo) + assert.Equal(t, true, bar) + assert.Equal(t, false, baz) + assert.Equal(t, false, biz) +} diff --git a/src/cfg/data_dir.go b/src/cfg/data_dir.go new file mode 100644 index 0000000..649bc15 --- /dev/null +++ b/src/cfg/data_dir.go @@ -0,0 +1,74 @@ +package cfg + +import ( + "context" + "fmt" + "os" + + "github.com/mediocregopher/mediocre-go-lib/v2/mctx" +) + +// DataDir manages the blog's data directory. +type DataDir struct { + Path string + + deleteOnClose bool +} + +// Init initializes the data directory, creating the directory named at path if +// it doesn't exist. +// +// If Path is not set, then a temporary directory will be created and its path +// set to the Path field. This directory will be removed when Close is called. +func (d *DataDir) Init() error { + if d.Path == "" { + + d.deleteOnClose = true + var err error + + if d.Path, err = os.MkdirTemp("", "mediocre-blog-data-*"); err != nil { + return fmt.Errorf("creating temporary directory: %w", err) + } + + return nil + } + + if err := os.MkdirAll(d.Path, 0700); err != nil { + return fmt.Errorf( + "creating directory (and parents) of %q: %w", + d.Path, + err, + ) + } + + return nil +} + +// SetupCfg implement the cfg.Cfger interface. +func (d *DataDir) SetupCfg(cfg *Cfg) { + + cfg.StringVar(&d.Path, "data-dir", "", "Directory to use for persistent storage. If unset a temp directory will be created, and will be deleted when the process exits.") + + cfg.OnInit(func(ctx context.Context) error { + return d.Init() + }) +} + +// Annotate implements mctx.Annotator interface. +func (d *DataDir) Annotate(a mctx.Annotations) { + a["dataDirPath"] = d.Path +} + +// Close cleans up any temporary state created by DataDir. +func (d *DataDir) Close() error { + + if !d.deleteOnClose { + return nil + } + + if err := os.RemoveAll(d.Path); err != nil { + return fmt.Errorf("removing temp dir %q: %w", d.Path, err) + } + + return nil +} diff --git a/src/cfg/mediocre_blog.go b/src/cfg/mediocre_blog.go new file mode 100644 index 0000000..98fe08c --- /dev/null +++ b/src/cfg/mediocre_blog.go @@ -0,0 +1,9 @@ +package cfg + +// this file contains functionality specific to the mediocre blog. + +// NewBlogCfg returns a Cfg specifically configured for mediocre blog processes. +func NewBlogCfg(params Params) *Cfg { + params.EnvPrefix = "MEDIOCRE_BLOG" + return New(params) +} -- cgit v1.2.3