Initial commit

This commit is contained in:
Adam Štrauch 2021-08-31 16:26:09 +02:00
commit 2f3698430b
Signed by: cx
GPG Key ID: 018304FFA8988F8D
8 changed files with 441 additions and 0 deletions

5
.gitignore vendored Normal file
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# Files with secrets
*secret*
# Binaries
lobby_*

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daemon/config.go Normal file
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package main
import (
"log"
"github.com/kelseyhightower/envconfig"
)
// Config keeps info about configuration of this daemon
type Config struct {
Token string `envconfig:"TOKEN" required:"false"` // not used yet
NATSURL string `envconfig:"NATS_URL" required:"true"`
Labels []string `envconfig:"LABELS" required:"false" default:""`
}
// GetConfig return configuration created based on environment variables
func GetConfig() *Config {
var config Config
err := envconfig.Process("", &config)
if err != nil {
log.Fatal(err.Error())
}
return &config
}

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daemon/identification.go Normal file
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package main
import (
"github.com/rosti-cz/server_lobby/server"
"github.com/shirou/gopsutil/v3/host"
)
func getIdentification() (server.Discovery, error) {
discovery := server.Discovery{}
info, err := host.Info()
if err != nil {
return discovery, err
}
discovery.Hostname = info.Hostname
discovery.Labels = config.Labels
return discovery, nil
}

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daemon/main.go Normal file
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package main
import (
"log"
"time"
"github.com/labstack/echo"
"github.com/labstack/echo/middleware"
"github.com/nats-io/nats.go"
"github.com/rosti-cz/server_lobby/server"
)
const discoveryChannel = "lobby.discovery"
const cleanEvery = 15 // clean discoveredServers every X seconds
const keepAlive = 15 // sends discovery struct every
var discoveryStorage server.Discoveries = server.Discoveries{}
var config Config
func init() {
discoveryStorage.LogChannel = make(chan string)
}
// cleanDiscoveryPool clears the local server map and keeps only the alive servers
func cleanDiscoveryPool() {
for {
discoveryStorage.Clean()
time.Sleep(cleanEvery * time.Second)
}
}
// sendDisoveryPacket sends discovery packet regularly so the network know we exist
func sendDisoveryPacket(nc *nats.Conn) {
for {
discovery, err := getIdentification()
if err != nil {
log.Printf("sending discovery identification error: %v\n", err)
}
data, err := discovery.Bytes()
if err != nil {
log.Printf("sending discovery formating message error: %v\n", err)
}
err = nc.Publish(discoveryChannel, data)
if err != nil {
log.Printf("sending discovery error: %v\n", err)
}
time.Sleep(keepAlive * time.Second)
}
}
// Print logs acquired from disovery storage
func printDiscoveryLogs() {
for {
logMessage := <-discoveryStorage.LogChannel
log.Println(logMessage)
}
}
func main() {
var err error
// Closing the logging channel
defer close(discoveryStorage.LogChannel)
// Load config from environment variables
config = *GetConfig()
// ------------------------
// Server discovering stuff
// ------------------------
// Connect to the NATS service
nc, err := nats.Connect(config.NATSURL)
if err != nil {
log.Fatalln(err)
}
defer nc.Drain()
go printDiscoveryLogs()
// Subscribe
log.Println("> discovery channel")
_, err = nc.Subscribe(discoveryChannel, discoveryHandler)
if err != nil {
log.Fatalln(err)
}
go cleanDiscoveryPool()
go sendDisoveryPacket(nc)
// --------
// REST API
// --------
e := echo.New()
// Middleware
e.Use(middleware.Logger())
e.Use(middleware.Recover())
// Routes
e.GET("/", func(c echo.Context) error {
discoveries := discoveryStorage.GetAll()
return c.JSONPretty(200, discoveries, " ")
})
// Start server
e.Logger.Fatal(e.Start(":1313"))
}

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package main
import (
"encoding/json"
"fmt"
"log"
"github.com/nats-io/nats.go"
"github.com/rosti-cz/server_lobby/server"
)
// discoveryHandler accepts discovery message and
func discoveryHandler(m *nats.Msg) {
message := server.Discovery{}
err := json.Unmarshal(m.Data, &message)
if err != nil {
log.Println(fmt.Errorf("decoding message error: %v", err))
}
err = message.Validate()
if err != nil {
log.Println(fmt.Errorf("validation error: %v", err))
}
discoveryStorage.Add(message)
}

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go.mod Normal file
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module github.com/rosti-cz/server_lobby
go 1.16
require (
github.com/dgrijalva/jwt-go v3.2.0+incompatible // indirect
github.com/golang/protobuf v1.5.2 // indirect
github.com/kelseyhightower/envconfig v1.4.0
github.com/labstack/echo v3.3.10+incompatible
github.com/labstack/gommon v0.3.0 // indirect
github.com/nats-io/nats-server/v2 v2.4.0 // indirect
github.com/nats-io/nats.go v1.12.0
github.com/shirou/gopsutil/v3 v3.21.7
github.com/valyala/fasttemplate v1.2.1 // indirect
golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4 // indirect
google.golang.org/protobuf v1.27.1 // indirect
)

109
go.sum Normal file
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@ -0,0 +1,109 @@
github.com/StackExchange/wmi v1.2.1 h1:VIkavFPXSjcnS+O8yTq7NI32k0R5Aj+v39y29VYDOSA=
github.com/StackExchange/wmi v1.2.1/go.mod h1:rcmrprowKIVzvc+NUiLncP2uuArMWLCbu9SBzvHz7e8=
github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/dgrijalva/jwt-go v3.2.0+incompatible h1:7qlOGliEKZXTDg6OTjfoBKDXWrumCAMpl/TFQ4/5kLM=
github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=
github.com/go-ole/go-ole v1.2.5 h1:t4MGB5xEDZvXI+0rMjjsfBsD7yAgp/s9ZDkL1JndXwY=
github.com/go-ole/go-ole v1.2.5/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
github.com/golang/protobuf v1.4.0-rc.1/go.mod h1:ceaxUfeHdC40wWswd/P6IGgMaK3YpKi5j83Wpe3EHw8=
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github.com/golang/protobuf v1.4.0-rc.2/go.mod h1:LlEzMj4AhA7rCAGe4KMBDvJI+AwstrUpVNzEA03Pprs=
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github.com/klauspost/compress v1.13.4/go.mod h1:8dP1Hq4DHOhN9w426knH3Rhby4rFm6D8eO+e+Dq5Gzg=
github.com/labstack/echo v3.3.10+incompatible h1:pGRcYk231ExFAyoAjAfD85kQzRJCRI8bbnE7CX5OEgg=
github.com/labstack/echo v3.3.10+incompatible/go.mod h1:0INS7j/VjnFxD4E2wkz67b8cVwCLbBmJyDaka6Cmk1s=
github.com/labstack/gommon v0.3.0 h1:JEeO0bvc78PKdyHxloTKiF8BD5iGrH8T6MSeGvSgob0=
github.com/labstack/gommon v0.3.0/go.mod h1:MULnywXg0yavhxWKc+lOruYdAhDwPK9wf0OL7NoOu+k=
github.com/mattn/go-colorable v0.1.2 h1:/bC9yWikZXAL9uJdulbSfyVNIR3n3trXl+v8+1sx8mU=
github.com/mattn/go-colorable v0.1.2/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
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github.com/minio/highwayhash v1.0.1/go.mod h1:BQskDq+xkJ12lmlUUi7U0M5Swg3EWR+dLTk+kldvVxY=
github.com/nats-io/jwt v1.2.2 h1:w3GMTO969dFg+UOKTmmyuu7IGdusK+7Ytlt//OYH/uU=
github.com/nats-io/jwt v1.2.2/go.mod h1:/xX356yQA6LuXI9xWW7mZNpxgF2mBmGecH+Fj34sP5Q=
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github.com/nats-io/jwt/v2 v2.0.3/go.mod h1:VRP+deawSXyhNjXmxPCHskrR6Mq50BqpEI5SEcNiGlY=
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github.com/nats-io/nats.go v1.12.0 h1:n0oZzK2aIZDMKuEiMKJ9qkCUgVY5vTAAksSXtLlz5Xc=
github.com/nats-io/nats.go v1.12.0/go.mod h1:BPko4oXsySz4aSWeFgOHLZs3G4Jq4ZAyE6/zMCxRT6w=
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golang.org/x/crypto v0.0.0-20210616213533-5ff15b29337e/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
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golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
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golang.org/x/time v0.0.0-20200416051211-89c76fbcd5d1/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
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golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
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google.golang.org/protobuf v0.0.0-20200221191635-4d8936d0db64/go.mod h1:kwYJMbMJ01Woi6D6+Kah6886xMZcty6N08ah7+eCXa0=
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server/main.go Normal file
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package server
import (
"encoding/json"
"fmt"
"time"
)
// ----------------
// Discovery struct
// ----------------
const TimeToLife = 60 // when server won't occur in the discovery channel longer than this, it should be considered as not-alive
// Discovery contains information about a single server and is used for server discovery
type Discovery struct {
Hostname string `json:"hostname"`
Labels []string `json:"labels"`
// For internal use to check if the server is still alive.
// Contains timestamp of the last check.
LastCheck int64 `json:"last_check"`
}
// Validate checks all values in the struct if the content is valid
func (d *Discovery) Validate() error {
// TODO: implement
return nil
}
// IsAlive return true if the server should be considered as alive
func (d *Discovery) IsAlive() bool {
return time.Now().Unix()-d.LastCheck < TimeToLife
}
func (d *Discovery) Bytes() ([]byte, error) {
data, err := json.Marshal(d)
return data, err
}
// -----------------
// Discovery storage
// -----------------
// Discoveries helps to store instances of Discovery struct and access them in thread safe mode
type Discoveries struct {
activeServers []Discovery
LogChannel chan string
}
// Add appends a new discovery/server to the storage
func (d *Discoveries) Add(discovery Discovery) {
if d.Exist(discovery.Hostname) {
d.Refresh(discovery.Hostname)
return
}
discovery.LastCheck = time.Now().Unix()
d.activeServers = append(d.activeServers, discovery)
if d.LogChannel != nil {
d.LogChannel <- fmt.Sprintf("%s registered", discovery.Hostname)
}
}
// Refresh updates
func (d *Discoveries) Refresh(hostname string) {
for idx, discovery := range d.activeServers {
if discovery.Hostname == hostname {
d.activeServers[idx].LastCheck = time.Now().Unix()
}
}
}
// Delete removes server identified by hostname from the storage
func (d *Discoveries) Delete(hostname string) {
if d.LogChannel != nil {
d.LogChannel <- fmt.Sprintf("removing %s", hostname)
}
newSet := []Discovery{}
for _, server := range d.activeServers {
if server.Hostname != hostname {
newSet = append(newSet, server)
}
}
d.activeServers = newSet
}
// Exist returns true if server with given hostname exists
func (d *Discoveries) Exist(hostname string) bool {
for _, server := range d.activeServers {
if server.Hostname == hostname {
return true
}
}
return false
}
// Get returns Discovery struct with the given hostname but it can be also an empty struct if it's not found. Check if hostname is empty or use Exist first to be sure.
func (d *Discoveries) Get(hostname string) Discovery {
for _, server := range d.activeServers {
if server.Hostname == hostname {
return server
}
}
return Discovery{}
}
// GetAll returns copy of the internal storage
func (d *Discoveries) GetAll() []Discovery {
return d.activeServers
}
// Clean checks loops over last check values for each discovery object and removes it if it's passed
func (d *Discoveries) Clean() {
newSet := []Discovery{}
for _, server := range d.activeServers {
if server.IsAlive() {
newSet = append(newSet, server)
} else {
if d.LogChannel != nil {
d.LogChannel <- fmt.Sprintf("%s not alive anymore", server.Hostname)
}
}
}
d.activeServers = newSet
}