A REST API for the DN42 registry, written in Go, to provide a bridge between interactive applications and the registry. https://explorer.burble.com
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//////////////////////////////////////////////////////////////////////////
// DN42 Registry API Server
//////////////////////////////////////////////////////////////////////////
package main
//////////////////////////////////////////////////////////////////////////
import (
"bufio"
// "errors"
"fmt"
log "github.com/sirupsen/logrus"
"io/ioutil"
"os"
"os/exec"
"strings"
"time"
)
//////////////////////////////////////////////////////////////////////////
// registry data model
// registry data
// Attributes within Objects
type RegAttribute struct {
Key string
Value string // this is a post-processed, or decorated value
RawValue string // the raw value as read from the registry
}
type RegObject struct {
Ref string // the ref contains the full path for this object
Data []*RegAttribute // the key/value data for this object
Backlinks []*RegObject // other objects that reference this one
}
// types are collections of objects
type RegType struct {
Ref string // full path for this type
Objects map[string]*RegObject // the objects in this type
}
// registry meta data
type RegAttributeSchema struct {
Fields []string
Relations []*RegType
}
type RegKeyIndex struct {
Ref string
Objects map[*RegObject][]*RegAttribute
}
type RegTypeSchema struct {
Ref string
Attributes map[string]*RegAttributeSchema
KeyIndex map[string]*RegKeyIndex
}
// the registry itself
type Registry struct {
Commit string
Schema map[string]*RegTypeSchema
Types map[string]*RegType
}
// and a variable for the actual data
var RegistryData *Registry
// store the previous commit
var previousCommit string
// also store the registry refresh ticker
var AuthorisationToken string
var RegistryRefresh chan bool
//////////////////////////////////////////////////////////////////////////
// utility and manipulation functions
// general functions
func RegistryMakePath(t string, o string) string {
return t + "/" + o
}
func RegistrySplitPath(p string) (string, string) {
tmp := strings.Split(p, "/")
if len(tmp) != 2 {
return "", ""
}
return tmp[0], tmp[1]
}
func (registry *Registry) GetObject(path string) *RegObject {
rtname, objname := RegistrySplitPath(path)
rtype := registry.Types[rtname]
if rtype == nil {
return nil
}
return rtype.Objects[objname]
}
// attribute functions
// nothing here
// object functions
// return attributes exactly matching a specific key
func (object *RegObject) GetKey(key string) []*RegAttribute {
attributes := make([]*RegAttribute, 0)
for _, a := range object.Data {
if a.Key == key {
attributes = append(attributes, a)
}
}
return attributes
}
// return a single key
func (object *RegObject) GetSingleKey(key string) *RegAttribute {
attributes := object.GetKey(key)
if len(attributes) != 1 {
log.WithFields(log.Fields{
"key": key,
"object": object.Ref,
}).Error("Unable to find unique key in object")
// can't register the object
return nil
}
return attributes[0]
}
// schema functions
// validate a set of attributes against a schema
func (schema *RegTypeSchema) validate(attributes []*RegAttribute) []*RegAttribute {
validated := make([]*RegAttribute, 0, len(attributes))
for _, attribute := range attributes {
// keys beginning with 'x-' are user defined, skip validation
if !strings.HasPrefix(attribute.Key, "x-") {
if schema.Attributes[attribute.Key] == nil {
// couldn't find a schema attribute
log.WithFields(log.Fields{
"key": attribute.Key,
"schema": schema.Ref,
}).Error("Schema validation failed")
// don't add to the validated list
continue
}
}
// all ok
validated = append(validated, attribute)
}
return validated
}
// add an attribute to the key map
func (schema *RegTypeSchema) addKeyIndex(object *RegObject,
attribute *RegAttribute) {
keyix := schema.KeyIndex[attribute.Key]
// create a new object map if it didn't exist
if keyix == nil {
keyix = &RegKeyIndex{
Ref: attribute.Key,
Objects: make(map[*RegObject][]*RegAttribute),
}
schema.KeyIndex[attribute.Key] = keyix
}
// add the object/attribute reference
keyix.Objects[object] = append(keyix.Objects[object], attribute)
}
// object functions
// add a backlink to an object
func (object *RegObject) addBacklink(ref *RegObject) {
// check if the backlink already exists, this could be the case
// if an object is referenced multiple times (e.g. admin-c & tech-c)
for _, blink := range object.Backlinks {
if blink == ref {
// already exists, just return as nothing to do
return
}
}
// didn't find a match, add the backlink
object.Backlinks = append(object.Backlinks, ref)
}
//////////////////////////////////////////////////////////////////////////
// reload the registry
func reloadRegistry(path string, commit string) {
log.Debug("Reloading registry")
// r will become the new registry data
registry := &Registry{
Commit: commit,
Schema: make(map[string]*RegTypeSchema),
Types: make(map[string]*RegType),
}
// bootstrap the schema registry type
registry.Types["schema"] = &RegType{
Ref: "schema",
Objects: make(map[string]*RegObject),
}
registry.loadType("schema", path)
// and parse the schema to get the remaining types
registry.parseSchema()
// now load the remaining types
for _, rType := range registry.Types {
registry.loadType(rType.Ref, path)
}
// mark relationships
registry.decorate()
// trigger updates in any other modules
EventBus.Fire("RegistryUpdate", registry, path)
// swap in the new registry data
RegistryData = registry
}
//////////////////////////////////////////////////////////////////////////
// create and load the raw data for a registry type
func (registry *Registry) loadType(typeName string, path string) {
// the type will already have been created
rType := registry.Types[typeName]
// as will the schema (unless attempting to load the schema itself)
schema := registry.Schema[typeName]
// special case for DNS as the directory
// doesn't match the type name
if typeName == "domain" {
path += "/dns"
} else {
path += "/" + typeName
}
// and load all the objects in this type
rType.loadObjects(schema, path)
}
//////////////////////////////////////////////////////////////////////////
// load all the objects associated with a type
func (rType *RegType) loadObjects(schema *RegTypeSchema, path string) {
entries, err := ioutil.ReadDir(path)
if err != nil {
log.WithFields(log.Fields{
"error": err,
"path": path,
"type": rType.Ref,
}).Error("Failed to read registry type directory")
return
}
// for each entry in the directory
for _, entry := range entries {
// each file maps to a registry object
if !entry.IsDir() {
filename := entry.Name()
// ignore dotfiles
if !strings.HasPrefix(filename, ".") {
// load the attributes from file
attributes := loadAttributes(path + "/" + filename)
// basic validation of attributes against the schema
// schema may be nil if we are actually loading the schema itself
if schema != nil {
attributes = schema.validate(attributes)
}
// make the object
object := &RegObject{
Ref: RegistryMakePath(rType.Ref, filename),
Data: attributes,
Backlinks: make([]*RegObject, 0),
}
// add to type
rType.Objects[filename] = object
}
}
}
log.WithFields(log.Fields{
"ref": rType.Ref,
"path": path,
"count": len(rType.Objects),
}).Debug("Loaded registry type")
}
//////////////////////////////////////////////////////////////////////////
// read attributes from a file
func loadAttributes(path string) []*RegAttribute {
attributes := make([]*RegAttribute, 0)
// open the file to start reading it
file, err := os.Open(path)
if err != nil {
log.WithFields(log.Fields{
"error": err,
"path": path,
}).Error("Failed to read attributes from file")
return attributes
}
defer file.Close()
// read the file line by line using the bufio scanner
scanner := bufio.NewScanner(file)
for scanner.Scan() {
line := strings.TrimRight(scanner.Text(), "\r\n")
// lines starting with '+' denote an empty line
if line[0] == '+' {
// concatenate a \n on to the previous attribute value
attributes[len(attributes)-1].RawValue += "\n"
} else {
// look for a : separator in the first 20 characters
ix := strings.IndexByte(line, ':')
if ix == -1 || ix >= 20 {
// couldn't find one
if len(line) <= 20 {
// hmmm, the line was shorter than 20 characters
// something is amiss
log.WithFields(log.Fields{
"length": len(line),
"path": path,
"line": line,
}).Warn("Short line detected")
} else {
// line is a continuation of the previous line, so
// concatenate the value on to the previous attribute value
attributes[len(attributes)-1].RawValue +=
"\n" + string(line[20:])
}
} else {
// found a key and : separator
// is there actually a value ?
var value string
if len(line) <= 20 {
// blank value
value = ""
} else {
value = string(line[20:])
}
// create a new attribute
a := &RegAttribute{
Key: string(line[:ix]),
RawValue: value,
}
attributes = append(attributes, a)
}
}
}
return attributes
}
//////////////////////////////////////////////////////////////////////////
// parse schema files to extract keys and for attribute relations
func (registry *Registry) parseSchema() {
// for each object in the schema type
for _, object := range registry.Types["schema"].Objects {
// look up the ref attribute
ref := object.GetSingleKey("ref")
if ref == nil {
log.WithFields(log.Fields{
"object": object.Ref,
}).Error("Schema record without ref")
// can't process this object
continue
}
// create the type schema object
typeName := strings.TrimPrefix(ref.RawValue, "dn42.")
typeSchema := &RegTypeSchema{
Ref: typeName,
Attributes: make(map[string]*RegAttributeSchema),
KeyIndex: make(map[string]*RegKeyIndex),
}
// ensure the type exists
rType := registry.Types[typeName]
if rType == nil {
rType := &RegType{
Ref: typeName,
Objects: make(map[string]*RegObject),
}
registry.Types[typeName] = rType
}
// for each key attribute in the schema
attributes := object.GetKey("key")
for _, attribute := range attributes {
// split the value on whitespace
fields := strings.Fields(attribute.RawValue)
keyName := fields[0]
typeSchema.Attributes[keyName] = &RegAttributeSchema{
Fields: fields[1:],
}
}
// register the type schema
registry.Schema[typeName] = typeSchema
}
// scan the fields of each schema attribute to determine relationships
// this needs to be second step to allow pre-creation of the types
for _, typeSchema := range registry.Schema {
for attribName, attribSchema := range typeSchema.Attributes {
for _, field := range attribSchema.Fields {
if strings.HasPrefix(field, "lookup=") {
// the relationships may be a multivalue, separated by ,
rels := strings.Split(strings.
TrimPrefix(field, "lookup="), ",")
// map to a regtype
relations := make([]*RegType, 0, len(rels))
for ix := range rels {
relName := strings.TrimPrefix(rels[ix], "dn42.")
relation := registry.Types[relName]
// log if unable to look up the type
if relation == nil {
// log unless this is the schema def lookup=str '>' [spec]...
if typeSchema.Ref != "schema" {
log.WithFields(log.Fields{
"relation": relName,
"attribute": attribName,
"type": typeSchema.Ref,
}).Error("Relation to type that does not exist")
}
} else {
// store the relationship
relations = append(relations, relation)
}
}
// register the relations
attribSchema.Relations = relations
// assume only 1 lookup= per key
break
}
}
}
}
log.Debug("Schema parsing complete")
}
//////////////////////////////////////////////////////////////////////////
// parse all attributes and decorate them
func (registry *Registry) decorate() {
cattribs := 0
cmatched := 0
// walk each attribute value
for _, rType := range registry.Types {
schema := registry.Schema[rType.Ref]
for _, object := range rType.Objects {
for _, attribute := range object.Data {
cattribs += 1
// add this attribute to the key map
schema.addKeyIndex(object, attribute)
attribSchema := schema.Attributes[attribute.Key]
// are there relations defined for this attribute ?
// attribSchema may be null if this attribute is user defined (x-*)
if (attribSchema != nil) &&
attribute.matchRelation(object, attribSchema.Relations) {
// matched
cmatched += 1
} else {
// no match, just copy the attribute data
attribute.Value = attribute.RawValue
}
}
}
}
log.WithFields(log.Fields{
"attributes": cattribs,
"matched": cmatched,
}).Debug("Decoration complete")
}
//////////////////////////////////////////////////////////////////////////
// match an attribute against schema relations
func (attribute *RegAttribute) matchRelation(parent *RegObject,
relations []*RegType) bool {
// it's not going to match if relations is empty
if relations == nil {
return false
}
// check each relation
for _, relation := range relations {
object := relation.Objects[attribute.RawValue]
if object != nil {
// found a match !
// decorate the attribute value
attribute.Value = fmt.Sprintf("[%s](%s)",
attribute.RawValue, object.Ref)
// and add a back reference to the related object
object.addBacklink(parent)
return true
}
}
// didn't find anything
return false
}
//////////////////////////////////////////////////////////////////////////
// fetch the current commit hash
func getCommitHash(regDir string, gitPath string) string {
// run git to get the latest commit hash
cmd := exec.Command(gitPath, "log", "-1", "--format=%H")
cmd.Dir = regDir
// execute
out, err := cmd.Output()
if err != nil {
log.WithFields(log.Fields{
"error": err,
"gitPath": gitPath,
"regDir": regDir,
}).Error("Failed to execute git log")
}
return strings.TrimSpace(string(out))
}
//////////////////////////////////////////////////////////////////////////
// refresh the registry
func refreshRegistry(regDir string, gitPath string, branch string) {
// run git fetch to get the current commits from the master
cmd := exec.Command(gitPath, "fetch")
cmd.Dir = regDir
// execute
if out, err := cmd.Output(); err != nil {
log.WithFields(log.Fields{
"error": err,
"gitPath": gitPath,
"regDir": regDir,
}).Error("Failed to execute git fetch")
} else {
fmt.Printf("Git Fetch: %s", string(out))
}
// then reset hard to match the master
cmd = exec.Command(gitPath, "reset", "--hard", "origin/"+branch)
cmd.Dir = regDir
// execute
if out, err := cmd.Output(); err != nil {
log.WithFields(log.Fields{
"error": err,
"gitPath": gitPath,
"regDir": regDir,
"branch": branch,
}).Error("Failed to execute git reset")
} else {
fmt.Printf("Git Reset: %s", string(out))
}
}
//////////////////////////////////////////////////////////////////////////
// called from main to initialse the registry data and syncing
func InitialiseRegistryData(regDir string, refresh time.Duration,
gitPath string, autoPull bool, branch string, token string) {
AuthorisationToken = token
// validate that the regDir/data path exists
dataPath := regDir + "/data"
regStat, err := os.Stat(dataPath)
if err != nil {
log.WithFields(log.Fields{
"error": err,
"path": dataPath,
}).Fatal("Unable to find registry directory")
}
// and it is a directory
if !regStat.IsDir() {
log.WithFields(log.Fields{
"error": err,
"path": dataPath,
}).Fatal("Registry path is not a directory")
}
// check that git exists
_, err = os.Stat(gitPath)
if err != nil {
log.WithFields(log.Fields{
"error": err,
"path": gitPath,
}).Fatal("Unable to find git executable")
}
// enforce a minimum update time
minTime := 10 * time.Minute
if refresh < minTime {
log.WithFields(log.Fields{
"interval": refresh,
}).Error("Enforcing minimum update time of 10 minutes")
refresh = minTime
}
// initialise the previous commit hash
// and do initial load from registry
previousCommit = getCommitHash(regDir, gitPath)
reloadRegistry(dataPath, previousCommit)
// create the refresh timer
RegistryRefresh = make(chan bool)
ticker := time.NewTicker(refresh)
go func() {
for {
select {
// when the ticker ticks
case <-RegistryRefresh:
case <-ticker.C:
}
log.Debug("Refresh Timer")
// automatically try to refresh the registry ?
if autoPull {
refreshRegistry(regDir, gitPath, branch)
}
// get the latest hash
currentCommit := getCommitHash(regDir, gitPath)
// has the registry been updated ?
if currentCommit != previousCommit {
log.WithFields(log.Fields{
"current": currentCommit,
"previous": previousCommit,
}).Info("Registry has changed, refresh started")
// refresh
reloadRegistry(dataPath, currentCommit)
// update commit
previousCommit = currentCommit
}
}
}()
}
//////////////////////////////////////////////////////////////////////////
// end of code