From ce8d74780610f33e85a7da0a9871b6c75131a8e2 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Mateusz=20=C5=81oskot?= Date: Fri, 27 Sep 2024 23:03:23 +0100 Subject: [PATCH] feat: add /env endpoint to allow exposing operator-controlled info from the server (#189) Fixes #114 --- httpbin/cmd/cmd.go | 69 +++++++++++++++++++++------------- httpbin/cmd/cmd_test.go | 56 ++++++++++++++++++++++++++- httpbin/handlers.go | 7 ++++ httpbin/handlers_test.go | 10 +++++ httpbin/httpbin.go | 5 +++ httpbin/options.go | 8 ++++ httpbin/responses.go | 4 ++ httpbin/static/index.html.tmpl | 1 + 8 files changed, 131 insertions(+), 29 deletions(-) diff --git a/httpbin/cmd/cmd.go b/httpbin/cmd/cmd.go index 08a98465..cdda27b5 100644 --- a/httpbin/cmd/cmd.go +++ b/httpbin/cmd/cmd.go @@ -25,6 +25,7 @@ const ( defaultListenHost = "0.0.0.0" defaultListenPort = 8080 defaultLogFormat = "text" + defaultEnvPrefix = "HTTPBIN_ENV_" // Reasonable defaults for our http server srvReadTimeout = 5 * time.Second @@ -35,13 +36,13 @@ const ( // Main is the main entrypoint for the go-httpbin binary. See loadConfig() for // command line argument parsing. func Main() int { - return mainImpl(os.Args[1:], os.Getenv, os.Hostname, os.Stderr) + return mainImpl(os.Args[1:], os.Getenv, os.Environ, os.Hostname, os.Stderr) } // mainImpl is the real implementation of Main(), extracted for better // testability. -func mainImpl(args []string, getEnv func(string) string, getHostname func() (string, error), out io.Writer) int { - cfg, err := loadConfig(args, getEnv, getHostname) +func mainImpl(args []string, getEnvVal func(string) string, getEnviron func() []string, getHostname func() (string, error), out io.Writer) int { + cfg, err := loadConfig(args, getEnvVal, getEnviron, getHostname) if err != nil { if cfgErr, ok := err.(ConfigError); ok { // for -h/-help, just print usage and exit without error @@ -75,6 +76,7 @@ func mainImpl(args []string, getEnv func(string) string, getHostname func() (str } opts := []httpbin.OptionFunc{ + httpbin.WithEnv(cfg.Env), httpbin.WithMaxBodySize(cfg.MaxBodySize), httpbin.WithMaxDuration(cfg.MaxDuration), httpbin.WithObserver(httpbin.StdLogObserver(logger)), @@ -110,6 +112,7 @@ func mainImpl(args []string, getEnv func(string) string, getHostname func() (str // config holds the configuration needed to initialize and run go-httpbin as a // standalone server. type config struct { + Env map[string]string AllowedRedirectDomains []string ListenHost string ExcludeHeaders string @@ -144,7 +147,7 @@ func (e ConfigError) Error() string { // loadConfig parses command line arguments and env vars into a fully resolved // Config struct. Command line arguments take precedence over env vars. -func loadConfig(args []string, getEnv func(string) string, getHostname func() (string, error)) (*config, error) { +func loadConfig(args []string, getEnvVal func(string) string, getEnviron func() []string, getHostname func() (string, error)) (*config, error) { cfg := &config{} fs := flag.NewFlagSet("go-httpbin", flag.ContinueOnError) @@ -192,24 +195,24 @@ func loadConfig(args []string, getEnv func(string) string, getHostname func() (s // Command line flags take precedence over environment vars, so we only // check for environment vars if we have default values for our command // line flags. - if cfg.MaxBodySize == httpbin.DefaultMaxBodySize && getEnv("MAX_BODY_SIZE") != "" { - cfg.MaxBodySize, err = strconv.ParseInt(getEnv("MAX_BODY_SIZE"), 10, 64) + if cfg.MaxBodySize == httpbin.DefaultMaxBodySize && getEnvVal("MAX_BODY_SIZE") != "" { + cfg.MaxBodySize, err = strconv.ParseInt(getEnvVal("MAX_BODY_SIZE"), 10, 64) if err != nil { - return nil, configErr("invalid value %#v for env var MAX_BODY_SIZE: parse error", getEnv("MAX_BODY_SIZE")) + return nil, configErr("invalid value %#v for env var MAX_BODY_SIZE: parse error", getEnvVal("MAX_BODY_SIZE")) } } - if cfg.MaxDuration == httpbin.DefaultMaxDuration && getEnv("MAX_DURATION") != "" { - cfg.MaxDuration, err = time.ParseDuration(getEnv("MAX_DURATION")) + if cfg.MaxDuration == httpbin.DefaultMaxDuration && getEnvVal("MAX_DURATION") != "" { + cfg.MaxDuration, err = time.ParseDuration(getEnvVal("MAX_DURATION")) if err != nil { - return nil, configErr("invalid value %#v for env var MAX_DURATION: parse error", getEnv("MAX_DURATION")) + return nil, configErr("invalid value %#v for env var MAX_DURATION: parse error", getEnvVal("MAX_DURATION")) } } - if cfg.ListenHost == defaultListenHost && getEnv("HOST") != "" { - cfg.ListenHost = getEnv("HOST") + if cfg.ListenHost == defaultListenHost && getEnvVal("HOST") != "" { + cfg.ListenHost = getEnvVal("HOST") } if cfg.Prefix == "" { - if prefix := getEnv("PREFIX"); prefix != "" { + if prefix := getEnvVal("PREFIX"); prefix != "" { cfg.Prefix = prefix } } @@ -221,29 +224,29 @@ func loadConfig(args []string, getEnv func(string) string, getHostname func() (s return nil, configErr("Prefix %#v must not end with a slash", cfg.Prefix) } } - if cfg.ExcludeHeaders == "" && getEnv("EXCLUDE_HEADERS") != "" { - cfg.ExcludeHeaders = getEnv("EXCLUDE_HEADERS") + if cfg.ExcludeHeaders == "" && getEnvVal("EXCLUDE_HEADERS") != "" { + cfg.ExcludeHeaders = getEnvVal("EXCLUDE_HEADERS") } - if cfg.ListenPort == defaultListenPort && getEnv("PORT") != "" { - cfg.ListenPort, err = strconv.Atoi(getEnv("PORT")) + if cfg.ListenPort == defaultListenPort && getEnvVal("PORT") != "" { + cfg.ListenPort, err = strconv.Atoi(getEnvVal("PORT")) if err != nil { - return nil, configErr("invalid value %#v for env var PORT: parse error", getEnv("PORT")) + return nil, configErr("invalid value %#v for env var PORT: parse error", getEnvVal("PORT")) } } - if cfg.TLSCertFile == "" && getEnv("HTTPS_CERT_FILE") != "" { - cfg.TLSCertFile = getEnv("HTTPS_CERT_FILE") + if cfg.TLSCertFile == "" && getEnvVal("HTTPS_CERT_FILE") != "" { + cfg.TLSCertFile = getEnvVal("HTTPS_CERT_FILE") } - if cfg.TLSKeyFile == "" && getEnv("HTTPS_KEY_FILE") != "" { - cfg.TLSKeyFile = getEnv("HTTPS_KEY_FILE") + if cfg.TLSKeyFile == "" && getEnvVal("HTTPS_KEY_FILE") != "" { + cfg.TLSKeyFile = getEnvVal("HTTPS_KEY_FILE") } if cfg.TLSCertFile != "" || cfg.TLSKeyFile != "" { if cfg.TLSCertFile == "" || cfg.TLSKeyFile == "" { return nil, configErr("https cert and key must both be provided") } } - if cfg.LogFormat == defaultLogFormat && getEnv("LOG_FORMAT") != "" { - cfg.LogFormat = getEnv("LOG_FORMAT") + if cfg.LogFormat == defaultLogFormat && getEnvVal("LOG_FORMAT") != "" { + cfg.LogFormat = getEnvVal("LOG_FORMAT") } if cfg.LogFormat != "text" && cfg.LogFormat != "json" { return nil, configErr(`invalid log format %q, must be "text" or "json"`, cfg.LogFormat) @@ -252,7 +255,7 @@ func loadConfig(args []string, getEnv func(string) string, getHostname func() (s // useRealHostname will be true if either the `-use-real-hostname` // arg is given on the command line or if the USE_REAL_HOSTNAME env var // is one of "1" or "true". - if useRealHostnameEnv := getEnv("USE_REAL_HOSTNAME"); useRealHostnameEnv == "1" || useRealHostnameEnv == "true" { + if useRealHostnameEnv := getEnvVal("USE_REAL_HOSTNAME"); useRealHostnameEnv == "1" || useRealHostnameEnv == "true" { cfg.rawUseRealHostname = true } if cfg.rawUseRealHostname { @@ -263,8 +266,8 @@ func loadConfig(args []string, getEnv func(string) string, getHostname func() (s } // split comma-separated list of domains into a slice, if given - if cfg.rawAllowedRedirectDomains == "" && getEnv("ALLOWED_REDIRECT_DOMAINS") != "" { - cfg.rawAllowedRedirectDomains = getEnv("ALLOWED_REDIRECT_DOMAINS") + if cfg.rawAllowedRedirectDomains == "" && getEnvVal("ALLOWED_REDIRECT_DOMAINS") != "" { + cfg.rawAllowedRedirectDomains = getEnvVal("ALLOWED_REDIRECT_DOMAINS") } for _, domain := range strings.Split(cfg.rawAllowedRedirectDomains, ",") { if strings.TrimSpace(domain) != "" { @@ -275,6 +278,18 @@ func loadConfig(args []string, getEnv func(string) string, getHostname func() (s // reset temporary fields to their zero values cfg.rawAllowedRedirectDomains = "" cfg.rawUseRealHostname = false + + for _, envVar := range getEnviron() { + name, value, _ := strings.Cut(envVar, "=") + if !strings.HasPrefix(name, defaultEnvPrefix) { + continue + } + if cfg.Env == nil { + cfg.Env = make(map[string]string) + } + cfg.Env[name] = value + } + return cfg, nil } diff --git a/httpbin/cmd/cmd_test.go b/httpbin/cmd/cmd_test.go index a0619876..ecf7065a 100644 --- a/httpbin/cmd/cmd_test.go +++ b/httpbin/cmd/cmd_test.go @@ -4,6 +4,7 @@ import ( "bytes" "errors" "flag" + "fmt" "os" "reflect" "testing" @@ -77,6 +78,49 @@ func TestLoadConfig(t *testing.T) { wantErr: flag.ErrHelp, }, + // env + "ok env with empty variables": { + env: map[string]string{}, + wantCfg: &config{ + Env: nil, + ListenHost: "0.0.0.0", + ListenPort: 8080, + MaxBodySize: httpbin.DefaultMaxBodySize, + MaxDuration: httpbin.DefaultMaxDuration, + LogFormat: defaultLogFormat, + }, + }, + "ok env with recognized variables": { + env: map[string]string{ + fmt.Sprintf("%sFOO", defaultEnvPrefix): "foo", + fmt.Sprintf("%s%sBAR", defaultEnvPrefix, defaultEnvPrefix): "bar", + fmt.Sprintf("%s123", defaultEnvPrefix): "123", + }, + wantCfg: &config{ + Env: map[string]string{ + fmt.Sprintf("%sFOO", defaultEnvPrefix): "foo", + fmt.Sprintf("%s%sBAR", defaultEnvPrefix, defaultEnvPrefix): "bar", + fmt.Sprintf("%s123", defaultEnvPrefix): "123", + }, + ListenHost: "0.0.0.0", + ListenPort: 8080, + MaxBodySize: httpbin.DefaultMaxBodySize, + MaxDuration: httpbin.DefaultMaxDuration, + LogFormat: defaultLogFormat, + }, + }, + "ok env with unrecognized variables": { + env: map[string]string{"HTTPBIN_FOO": "foo", "BAR": "bar"}, + wantCfg: &config{ + Env: nil, + ListenHost: "0.0.0.0", + ListenPort: 8080, + MaxBodySize: httpbin.DefaultMaxBodySize, + MaxDuration: httpbin.DefaultMaxDuration, + LogFormat: defaultLogFormat, + }, + }, + // max body size "invalid -max-body-size": { args: []string{"-max-body-size", "foo"}, @@ -515,7 +559,7 @@ func TestLoadConfig(t *testing.T) { if tc.getHostname == nil { tc.getHostname = getHostnameDefault } - cfg, err := loadConfig(tc.args, func(key string) string { return tc.env[key] }, tc.getHostname) + cfg, err := loadConfig(tc.args, func(key string) string { return tc.env[key] }, func() []string { return environSlice(tc.env) }, tc.getHostname) switch { case tc.wantErr != nil && err != nil: @@ -606,7 +650,7 @@ func TestMainImpl(t *testing.T) { } buf := &bytes.Buffer{} - gotCode := mainImpl(tc.args, func(key string) string { return tc.env[key] }, tc.getHostname, buf) + gotCode := mainImpl(tc.args, func(key string) string { return tc.env[key] }, func() []string { return environSlice(tc.env) }, tc.getHostname, buf) out := buf.String() if gotCode != tc.wantCode { @@ -625,3 +669,11 @@ func TestMainImpl(t *testing.T) { }) } } + +func environSlice(env map[string]string) []string { + envStrings := make([]string, 0, len(env)) + for name, value := range env { + envStrings = append(envStrings, fmt.Sprintf("%s=%s", name, value)) + } + return envStrings +} diff --git a/httpbin/handlers.go b/httpbin/handlers.go index 16503f6a..fbd3d46b 100644 --- a/httpbin/handlers.go +++ b/httpbin/handlers.go @@ -35,6 +35,13 @@ func (h *HTTPBin) Index(w http.ResponseWriter, r *http.Request) { writeHTML(w, h.indexHTML, http.StatusOK) } +// Env - returns environment variables with HTTPBIN_ prefix, if any pre-configured by operator +func (h *HTTPBin) Env(w http.ResponseWriter, _ *http.Request) { + writeJSON(http.StatusOK, w, &envResponse{ + Env: h.env, + }) +} + // FormsPost renders an HTML form that submits a request to the /post endpoint func (h *HTTPBin) FormsPost(w http.ResponseWriter, _ *http.Request) { writeHTML(w, h.formsPostHTML, http.StatusOK) diff --git a/httpbin/handlers_test.go b/httpbin/handlers_test.go index 048c6845..27b1a5a0 100644 --- a/httpbin/handlers_test.go +++ b/httpbin/handlers_test.go @@ -120,6 +120,16 @@ func TestIndex(t *testing.T) { } } +func TestEnv(t *testing.T) { + t.Run("default environment", func(t *testing.T) { + t.Parallel() + req := newTestRequest(t, "GET", "/env") + resp := must.DoReq(t, client, req) + result := mustParseResponse[envResponse](t, resp) + assert.Equal(t, len(result.Env), 0, "environment variables unexpected") + }) +} + func TestFormsPost(t *testing.T) { t.Parallel() diff --git a/httpbin/httpbin.go b/httpbin/httpbin.go index 82ae6e6b..7c60924a 100644 --- a/httpbin/httpbin.go +++ b/httpbin/httpbin.go @@ -57,6 +57,10 @@ type HTTPBin struct { // Set of hosts to which the /redirect-to endpoint will allow redirects AllowedRedirectDomains map[string]struct{} + // The operator-controlled environment variables filtered from + // the process environment, based on named HTTPBIN_ prefix. + env map[string]string + // Pre-computed error message for the /redirect-to endpoint, based on // -allowed-redirect-domains/ALLOWED_REDIRECT_DOMAINS forbiddenRedirectError string @@ -159,6 +163,7 @@ func (h *HTTPBin) Handler() http.Handler { mux.HandleFunc("/digest-auth/{qop}/{user}/{password}/{algorithm}", h.DigestAuth) mux.HandleFunc("/drip", h.Drip) mux.HandleFunc("/dump/request", h.DumpRequest) + mux.HandleFunc("/env", h.Env) mux.HandleFunc("/etag/{etag}", h.ETag) mux.HandleFunc("/gzip", h.Gzip) mux.HandleFunc("/headers", h.Headers) diff --git a/httpbin/options.go b/httpbin/options.go index e697a1c1..15f60904 100644 --- a/httpbin/options.go +++ b/httpbin/options.go @@ -46,6 +46,14 @@ func WithObserver(o Observer) OptionFunc { } } +// WithEnv sets the HTTPBIN_-prefixed environment variables reported +// by the /env endpoint. +func WithEnv(env map[string]string) OptionFunc { + return func(h *HTTPBin) { + h.env = env + } +} + // WithExcludeHeaders sets the headers to exclude in outgoing responses, to // prevent possible information leakage. func WithExcludeHeaders(excludeHeaders string) OptionFunc { diff --git a/httpbin/responses.go b/httpbin/responses.go index 6b1e82be..d05d525a 100644 --- a/httpbin/responses.go +++ b/httpbin/responses.go @@ -13,6 +13,10 @@ const ( textContentType = "text/plain; charset=utf-8" ) +type envResponse struct { + Env map[string]string `json:"env"` +} + type headersResponse struct { Headers http.Header `json:"headers"` } diff --git a/httpbin/static/index.html.tmpl b/httpbin/static/index.html.tmpl index d70030a4..0cf8b772 100644 --- a/httpbin/static/index.html.tmpl +++ b/httpbin/static/index.html.tmpl @@ -82,6 +82,7 @@
  • {{.Prefix}}/drip?numbytes=n&duration=s&delay=s&code=code Drips data over the given duration after an optional initial delay, simulating a slow HTTP server.
  • {{.Prefix}}/dump/request Returns the given request in its HTTP/1.x wire approximate representation.
  • {{.Prefix}}/encoding/utf8 Returns page containing UTF-8 data.
    • +
  • {{.Prefix}}/env Returns all environment variables named with HTTPBIN_ENV_ prefix.
  • {{.Prefix}}/etag/:etag Assumes the resource has the given etag and responds to If-None-Match header with a 200 or 304 and If-Match with a 200 or 412 as appropriate.
  • {{.Prefix}}/forms/post HTML form that submits to {{.Prefix}}/post
  • {{.Prefix}}/get Returns GET data.