133 lines
3.6 KiB
Go
133 lines
3.6 KiB
Go
/*
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Copyright 2021 The Dapr Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package kubernetes
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import (
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"bytes"
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"context"
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"fmt"
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"net"
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"strconv"
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"strings"
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"text/template"
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"github.com/dapr/components-contrib/nameresolution"
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"github.com/dapr/kit/config"
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"github.com/dapr/kit/logger"
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)
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const (
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DefaultClusterDomain = "cluster.local"
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ClusterDomainKey = "clusterDomain"
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TemplateKey = "template"
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)
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// Compile-time interface assertions
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var (
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_ nameresolution.Resolver = (*resolver)(nil)
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_ nameresolution.ResolverMulti = (*resolver)(nil)
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)
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func executeTemplateWithResolveRequest(tmpl *template.Template, req nameresolution.ResolveRequest) (string, error) {
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var addr bytes.Buffer
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if err := tmpl.Execute(&addr, req); err != nil {
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return "", err
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}
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return addr.String(), nil
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}
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type resolver struct {
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logger logger.Logger
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clusterDomain string
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tmpl *template.Template
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}
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// NewResolver creates Kubernetes name resolver.
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func NewResolver(logger logger.Logger) nameresolution.Resolver {
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return &resolver{
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logger: logger,
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clusterDomain: DefaultClusterDomain,
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tmpl: nil,
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}
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}
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// Init initializes Kubernetes name resolver.
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func (k *resolver) Init(ctx context.Context, metadata nameresolution.Metadata) error {
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configInterface, err := config.Normalize(metadata.Configuration)
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if err != nil {
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return err
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}
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if cfg, ok := configInterface.(map[string]interface{}); ok {
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clusterDomainAny := cfg[ClusterDomainKey]
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tmplStrAny := cfg[TemplateKey]
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if clusterDomainAny != nil {
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clusterDomain, _ := clusterDomainAny.(string)
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if clusterDomain != "" {
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k.clusterDomain = clusterDomain
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}
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}
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if tmplStrAny != nil {
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tmplStr, _ := tmplStrAny.(string)
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if tmplStr != "" {
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k.tmpl = template.Must(template.New("kubernetes-template").Parse(tmplStr))
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k.logger.Debugf("using custom template %s", tmplStr)
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}
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}
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}
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return nil
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}
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// ResolveID resolves name to address in Kubernetes.
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func (k *resolver) ResolveID(ctx context.Context, req nameresolution.ResolveRequest) (string, error) {
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if k.tmpl != nil {
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return executeTemplateWithResolveRequest(k.tmpl, req)
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}
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// Dapr requires this formatting for Kubernetes services
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return req.ID + "-dapr." + req.Namespace + ".svc." + k.clusterDomain + ":" + strconv.Itoa(req.Port), nil
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}
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// ResolveIDMulti resolves an app-id to a set of IP addresses in Kubernetes
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func (k *resolver) ResolveIDMulti(ctx context.Context, req nameresolution.ResolveRequest) (nameresolution.AddressList, error) {
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// First, get the address from ResolveID, which is usually a DNS name
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addr, err := k.ResolveID(ctx, req)
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if err != nil {
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return nil, err
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}
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// Extract the port if present
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var port string
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idx := strings.LastIndexByte(addr, ':')
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if idx > -1 && (idx+1) < len(addr) {
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port = addr[(idx + 1):]
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addr = addr[:idx]
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}
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// Resolve the DNS name for a list of IPv4 or IPv6
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ips, err := net.LookupIP(addr)
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if err != nil {
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return nil, fmt.Errorf("failed to resolve address for '%s': %w", addr, err)
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}
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// Return a list of IPs + port
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res := make(nameresolution.AddressList, len(ips))
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for i, ip := range ips {
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res[i] = net.JoinHostPort(ip.String(), port)
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}
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return res, nil
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}
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