feat: announcements support (#501)

* feat: add announcement banner component

* feat: read announcement from env

* chore: add announcement docs

* fix: prettier

* fix: hide banner on close

* fix: add info banner styles

Author: x1unix

Makefile

@@ -53,6 +53,10 @@ cover:
 	@cat tools/cover.txt | xargs go test -v -covermode=count -coverprofile=/tmp/cover.out && \
 	go tool cover -html=/tmp/cover.out
 
+.PHONY:announcement
+announcement:
+	@go run ./cmd/announcements -f "$(SRC_FILE)"
+
 .PHONY: install
 install:
 	@if [ ! -d "./target" ]; then echo "ERROR: Please build project first by calling 'make'." && exit 2; fi

cmd/announcements/main.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/x1unix/go-playground/internal/announcements"
+)
+
+type flagValues struct {
+	isDecode bool
+	fileName string
+}
+
+func main() {
+	vals := &flagValues{}
+	flag.BoolVar(&vals.isDecode, "d", false, "Decode a given announcement file")
+	flag.StringVar(&vals.fileName, "f", "", "File name")
+	flag.Parse()
+
+	if err := mainErr(vals); err != nil {
+		log.Fatalln(err)
+	}
+}
+
+func mainErr(vals *flagValues) error {
+	if vals.fileName == "" {
+		return errors.New("missing file name")
+	}
+
+	data, err := os.ReadFile(vals.fileName)
+	if err != nil {
+		return fmt.Errorf("can't open input file: %w", err)
+	}
+
+	if vals.isDecode {
+		out, err := announcements.DecodeFromBase64(string(data))
+		if err != nil {
+			return err
+		}
+
+		enc := json.NewEncoder(os.Stdout)
+		enc.SetIndent("", "  ")
+		return enc.Encode(out)
+	}
+
+	v := &announcements.Announcement{}
+	if err := json.Unmarshal(data, v); err != nil {
+		return fmt.Errorf("can't parse input announcement from JSON: %w", err)
+	}
+
+	if err := v.Validate(); err != nil {
+		return err
+	}
+
+	out, err := announcements.Encode(v)
+	if err != nil {
+		return err
+	}
+
+	_, _ = fmt.Fprint(os.Stdout, out)
+	return nil
+}

cmd/playground/main.go

@@ -86,7 +86,10 @@ func start(logger *zap.Logger, cfg *config.Config) error {
 	// Initialize API endpoints
 	r := mux.NewRouter()
 	apiRouter := r.PathPrefix("/api").Subrouter()
-	svcCfg := server.ServiceConfig{Version: Version}
+	svcCfg := server.ServiceConfig{
+		Version:      Version,
+		Announcement: cfg.Misc.Announcement.Value,
+	}
 	server.NewAPIv1Handler(svcCfg, playgroundClient, buildSvc, backendsInfoSvc).
 		Mount(apiRouter)
 

docs/deployment/docker/README.md

@@ -36,6 +36,20 @@ Playground server can be configured using environment variables described below.
 | `HTTP_READ_TIMEOUT`    | `15s`                          | HTTP request read timeout.                                                                       |
 | `HTTP_WRITE_TIMEOUT`   | `60s`                          | HTTP response timeout.                                                                           |
 | `HTTP_IDLE_TIMEOUT`    | `90s`                          | HTTP keep alive timeout.                                                                         |
+| `SERVER_ANNOUNCEMENT`  |                                | Server announcement message to be displayed on top of page. See [Announcements](#announcements)  |
+
+#### Announcements
+
+Service supports displaying service announcements on a top of a page.\
+This is used to notify users about news suchs as planned server downtime or other important information.
+
+Announcement file is a base64-encoded msgpack string passed into `SERVER_ANNOUNCEMENT` environment variable.
+
+##### Encode announcement
+
+Use [this tool](../../../cmd/announcements/main.go) to encode a JSON file into a encoded announcement string.
+
+Announcement schema can be found [here](../../../internal/announcements/types.go).
 
 ## Building custom image
 

go.mod

@@ -8,17 +8,19 @@ require (
 	github.com/TheZeroSlave/zapsentry v1.10.0
 	github.com/avast/retry-go v3.0.0+incompatible
 	github.com/gorilla/mux v1.7.3
+	github.com/hashicorp/go-set/v3 v3.0.0
 	github.com/kelseyhightower/envconfig v1.4.0
 	github.com/pkg/errors v0.8.1
 	github.com/samber/lo v1.38.1
+	github.com/spf13/cobra v1.8.1
 	github.com/stretchr/testify v1.8.2
 	github.com/tevino/abool v0.0.0-20170917061928-9b9efcf221b5
-	github.com/traefik/yaegi v0.15.1
+	github.com/vmihailenco/msgpack/v5 v5.4.1
 	github.com/x1unix/foundation v1.0.0
+	go.uber.org/automaxprocs v1.6.0
 	go.uber.org/mock v0.4.0
 	go.uber.org/zap v1.21.0
 	golang.org/x/exp v0.0.0-20230321023759-10a507213a29
-	golang.org/x/mod v0.14.0
 	golang.org/x/sync v0.7.0
 	golang.org/x/time v0.0.0-20201208040808-7e3f01d25324
 )
@@ -27,16 +29,12 @@ require (
 	github.com/benbjohnson/clock v1.1.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/getsentry/sentry-go v0.13.0 // indirect
-	github.com/hashicorp/go-set/v3 v3.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/spf13/cobra v1.8.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/vmihailenco/tagparser/v2 v2.0.0 // indirect
 	go.uber.org/atomic v1.9.0 // indirect
-	go.uber.org/automaxprocs v1.6.0 // indirect
 	go.uber.org/multierr v1.8.0 // indirect
 	golang.org/x/sys v0.21.0 // indirect
-	google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.5.1 // indirect
-	google.golang.org/protobuf v1.34.2 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -11,7 +11,9 @@ github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/getsentry/sentry-go v0.13.0 h1:20dgTiUSfxRB/EhMPtxcL9ZEbM1ZdR+W/7f7NWD+xWo=
 github.com/getsentry/sentry-go v0.13.0/go.mod h1:EOsfu5ZdvKPfeHYV6pTVQnsjfp30+XA7//UooKNumH0=
 github.com/go-errors/errors v1.0.1 h1:LUHzmkK3GUKUrL/1gfBUxAHzcev3apQlezX/+O7ma6w=
-github.com/google/go-cmp v0.5.8 h1:e6P7q2lk1O+qJJb4BtCQXlK8vWEO8V1ZeuEdJNOqZyg=
+github.com/go-errors/errors v1.0.1/go.mod h1:f4zRHt4oKfwPJE5k8C9vpYG+aDHdBFUsgrm6/TyX73Q=
+github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
+github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/gorilla/mux v1.7.3 h1:gnP5JzjVOuiZD07fKKToCAOjS0yOpj/qPETTXCCS6hw=
 github.com/gorilla/mux v1.7.3/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
 github.com/hashicorp/go-set/v3 v3.0.0 h1:CaJBQvQCOWoftrBcDt7Nwgo0kdpmrKxar/x2o6pV9JA=
@@ -26,13 +28,18 @@ github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/pingcap/errors v0.11.4 h1:lFuQV/oaUMGcD2tqt+01ROSmJs75VG1ToEOkZIZ4nE4=
+github.com/pingcap/errors v0.11.4/go.mod h1:Oi8TUi2kEtXXLMJk9l1cGmz20kV3TaQ0usTwv5KuLY8=
 github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/prashantv/gostub v1.1.0 h1:BTyx3RfQjRHnUWaGF9oQos79AlQ5k8WNktv7VGvVH4g=
+github.com/prashantv/gostub v1.1.0/go.mod h1:A5zLQHz7ieHGG7is6LLXLz7I8+3LZzsrV0P1IAHhP5U=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/samber/lo v1.38.1 h1:j2XEAqXKb09Am4ebOg31SpvzUTTs6EN3VfgeLUhPdXM=
 github.com/samber/lo v1.38.1/go.mod h1:+m/ZKRl6ClXCE2Lgf3MsQlWfh4bn1bz6CXEOxnEXnEA=
+github.com/shoenig/test v1.11.0 h1:NoPa5GIoBwuqzIviCrnUJa+t5Xb4xi5Z+zODJnIDsEQ=
+github.com/shoenig/test v1.11.0/go.mod h1:UxJ6u/x2v/TNs/LoLxBNJRV9DiwBBKYxXSyczsBHFoI=
 github.com/spf13/cobra v1.8.1 h1:e5/vxKd/rZsfSJMUX1agtjeTDf+qv1/JdBF8gg5k9ZM=
 github.com/spf13/cobra v1.8.1/go.mod h1:wHxEcudfqmLYa8iTfL+OuZPbBZkmvliBWKIezN3kD9Y=
 github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
@@ -48,8 +55,10 @@ github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ
 github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/tevino/abool v0.0.0-20170917061928-9b9efcf221b5 h1:hNna6Fi0eP1f2sMBe/rJicDmaHmoXGe1Ta84FPYHLuE=
 github.com/tevino/abool v0.0.0-20170917061928-9b9efcf221b5/go.mod h1:f1SCnEOt6sc3fOJfPQDRDzHOtSXuTtnz0ImG9kPRDV0=
-github.com/traefik/yaegi v0.15.1 h1:YA5SbaL6HZA0Exh9T/oArRHqGN2HQ+zgmCY7dkoTXu4=
-github.com/traefik/yaegi v0.15.1/go.mod h1:AVRxhaI2G+nUsaM1zyktzwXn69G3t/AuTDrCiTds9p0=
+github.com/vmihailenco/msgpack/v5 v5.4.1 h1:cQriyiUvjTwOHg8QZaPihLWeRAAVoCpE00IUPn0Bjt8=
+github.com/vmihailenco/msgpack/v5 v5.4.1/go.mod h1:GaZTsDaehaPpQVyxrf5mtQlH+pc21PIudVV/E3rRQok=
+github.com/vmihailenco/tagparser/v2 v2.0.0 h1:y09buUbR+b5aycVFQs/g70pqKVZNBmxwAhO7/IwNM9g=
+github.com/vmihailenco/tagparser/v2 v2.0.0/go.mod h1:Wri+At7QHww0WTrCBeu4J6bNtoV6mEfg5OIWRZA9qds=
 github.com/x1unix/foundation v1.0.0 h1:tG0dG1sbiF9TGrjwns+wtX5feBprRD5iTvpmgQDnacA=
 github.com/x1unix/foundation v1.0.0/go.mod h1:y9E4igeUWi+njm4xCM48NItLhVH/Jj1KGE069I3J5Hc=
 github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
@@ -73,25 +82,19 @@ golang.org/x/exp v0.0.0-20230321023759-10a507213a29 h1:ooxPy7fPvB4kwsA2h+iBNHkAb
 golang.org/x/exp v0.0.0-20230321023759-10a507213a29/go.mod h1:CxIveKay+FTh1D0yPZemJVgC/95VzuuOLq5Qi4xnoYc=
 golang.org/x/lint v0.0.0-20190930215403-16217165b5de/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
-golang.org/x/mod v0.14.0 h1:dGoOF9QVLYng8IHTm7BAyWqCqSheQ5pYWGhzW00YJr0=
-golang.org/x/mod v0.14.0/go.mod h1:hTbmBsO62+eylJbnUtE2MGJUyE7QWk4xUqPFrRgJ+7c=
 golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.2.0 h1:PUR+T4wwASmuSTYdKjYHI5TD22Wy5ogLU5qZCOLxBrI=
-golang.org/x/sync v0.2.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.7.0 h1:YsImfSBoP9QPYL0xyKJPq0gcaJdG3rInoqxTWbfQu9M=
 golang.org/x/sync v0.7.0/go.mod h1:Czt+wKu1gCyEFDUtn0jG5QVvpJ6rzVqr5aXyt9drQfk=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.3.0 h1:w8ZOecv6NaNa/zC8944JTU3vz4u6Lagfk4RPQxv92NQ=
-golang.org/x/sys v0.3.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.21.0 h1:rF+pYz3DAGSQAxAu1CbC7catZg4ebC4UIeIhKxBZvws=
 golang.org/x/sys v0.21.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
@@ -106,12 +109,6 @@ golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.5.1 h1:F29+wU6Ee6qgu9TddPgooOdaqsxTMunOoj8KA5yuS5A=
-google.golang.org/grpc/cmd/protoc-gen-go-grpc v1.5.1/go.mod h1:5KF+wpkbTSbGcR9zteSqZV6fqFOWBl4Yde8En8MryZA=
-google.golang.org/protobuf v1.34.1 h1:9ddQBjfCyZPOHPUiPxpYESBLc+T8P3E+Vo4IbKZgFWg=
-google.golang.org/protobuf v1.34.1/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
-google.golang.org/protobuf v1.34.2 h1:6xV6lTsCfpGD21XK49h7MhtcApnLqkfYgPcdHftf6hg=
-google.golang.org/protobuf v1.34.2/go.mod h1:qYOHts0dSfpeUzUFpOMr/WGzszTmLH+DiWniOlNbLDw=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=

internal/announcements/decode.go

@@ -0,0 +1,80 @@
+package announcements
+
+import (
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+
+	"github.com/vmihailenco/msgpack/v5"
+)
+
+type TextMarshaler struct {
+	Value *Announcement
+}
+
+func (a *TextMarshaler) MarshalText() ([]byte, error) {
+	if a.Value == nil {
+		return nil, nil
+	}
+
+	encoded, err := Encode(a.Value)
+	if err != nil {
+		return nil, err
+	}
+
+	return []byte(encoded), nil
+}
+
+func (a *TextMarshaler) UnmarshalText(data []byte) error {
+	if len(data) == 0 {
+		return nil
+	}
+
+	decoded, err := DecodeFromBase64(string(data))
+	if err != nil {
+		return err
+	}
+
+	a.Value = decoded
+	return nil
+}
+
+// DecodeFromBase64 decodes announcement from base64 string, validates it and returns.
+func DecodeFromBase64(payload string) (*Announcement, error) {
+	if payload == "" {
+		return nil, nil
+	}
+
+	rawMsg, err := base64.StdEncoding.DecodeString(payload)
+	if err != nil {
+		return nil, fmt.Errorf("can't decode announcement from base64: %w", err)
+	}
+
+	msg := &Announcement{}
+	if err := msgpack.Unmarshal(rawMsg, msg); err != nil {
+		return nil, fmt.Errorf("can't decode announcenment from msgpack: %w", err)
+	}
+
+	if err := msg.Validate(); err != nil {
+		return nil, fmt.Errorf("invalid announcement contents: %w", err)
+	}
+
+	if msg.Key == "" {
+		// auto-compute announcement key
+		hash := sha256.Sum256(rawMsg)
+		msg.Key = hex.EncodeToString(hash[:])
+	}
+
+	return msg, nil
+}
+
+// Encode encodes announcement message into a msgpack base64 string.
+func Encode(msg *Announcement) (string, error) {
+	data, err := msgpack.Marshal(msg)
+	if err != nil {
+		return "", fmt.Errorf("can't encode message to msgpack: %w", err)
+	}
+
+	return base64.StdEncoding.EncodeToString(data), nil
+}

internal/announcements/decode_test.go

@@ -0,0 +1,30 @@
+package announcements
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestEncodeDecode(t *testing.T) {
+	testAnnouncement := &Announcement{
+		Key:  "test",
+		Type: "info",
+		Content: []MessagePart{
+			{
+				Type:  "text",
+				Value: "hello world",
+			},
+		},
+	}
+
+	m := TextMarshaler{Value: testAnnouncement}
+	encoded, err := m.MarshalText()
+	require.NoError(t, err)
+	require.NotEmpty(t, encoded)
+
+	m.Value = nil
+	err = m.UnmarshalText(encoded)
+	require.NoError(t, err)
+	require.Equal(t, testAnnouncement, m.Value)
+}

internal/announcements/types.go

@@ -0,0 +1,38 @@
+package announcements
+
+import (
+	"errors"
+	"fmt"
+)
+
+// AnnouncementMessagePart represents a part of an announcement message
+type MessagePart struct {
+	Type  string `json:"type" msgpack:"type"` // "link" or "text"
+	Value string `json:"value" msgpack:"value"`
+	Label string `json:"label,omitempty" msgpack:"label,omitempty"`
+	Style string `json:"style,omitempty" msgpack:"style,omitempty"` // "bold", "italic", or "underline"
+}
+
+// AnnouncementMessage represents a complete announcement message
+type Announcement struct {
+	Key          string        `json:"key" msgpack:"key"`
+	Type         string        `json:"type" msgpack:"type"` // "info", "error", "warning", or "success"
+	IsIconHidden bool          `json:"isIconHidden,omitempty" msgpack:"isIconHidden,omitempty"`
+	IsCentered   bool          `json:"isCentered,omitempty" msgpack:"isCentered,omitempty"`
+	Content      []MessagePart `json:"content" msgpack:"content"`
+}
+
+func (msg Announcement) Validate() error {
+	switch msg.Type {
+	case "info", "error", "warning", "success":
+		break
+	default:
+		return fmt.Errorf("invalid announcement message type: %q", msg.Type)
+	}
+
+	if len(msg.Content) == 0 {
+		return errors.New("missing announcement message content")
+	}
+
+	return nil
+}