add webhook client

src/pkg/webhook/builder.go

@@ -0,0 +1,79 @@
+/*
+Copyright 2022 Amazon.com, Inc. or its affiliates. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package webhook
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	urlpkg "net/url"
+	templatepkg "text/template"
+	"time"
+)
+
+type (
+	HttpSendFunc = func(*http.Request) (*http.Response, error)
+	ProxyFunc    = func(*http.Request) (*url.URL, error)
+
+	ClientBuilder func(ProxyFunc) HttpSendFunc
+)
+
+func NewHttpClientDo(proxy ProxyFunc) HttpSendFunc {
+	c := &http.Client{
+		Timeout: 5 * time.Second,
+		Transport: &http.Transport{
+			IdleConnTimeout: 1 * time.Second,
+			Proxy:           proxy,
+		},
+	}
+	return c.Do
+}
+
+func (b ClientBuilder) NewClient(url, proxyURL, template string, headers http.Header) (Client, error) {
+	c := Client{}
+
+	if url == "" {
+		return c, nil
+	}
+
+	proxy := noopProxy
+	if proxyURL != "" {
+		proxyURL, err := urlpkg.Parse(proxyURL)
+		if err != nil {
+			return c, fmt.Errorf("failed to parse proxy URL: %w", err)
+		}
+
+		proxy = func(_ *http.Request) (*urlpkg.URL, error) {
+			return proxyURL, nil
+		}
+	}
+
+	tmpl, err := templatepkg.New("webhook").Parse(template)
+	if err != nil {
+		return c, fmt.Errorf("failed to parse template: %w", err)
+	}
+
+	c.url = url
+	c.headers = headers
+	c.sendFunc = b(proxy)
+	c.template = tmpl
+	return c, nil
+}
+
+func noopProxy(_ *http.Request) (*url.URL, error) {
+	return nil, nil
+}

src/pkg/webhook/client.go

@@ -0,0 +1,76 @@
+/*
+Copyright 2022 Amazon.com, Inc. or its affiliates. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package webhook
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"net/http"
+	templatepkg "text/template"
+
+	"github.com/aws/aws-node-termination-handler/pkg/logging"
+)
+
+type Client struct {
+	url      string
+	headers  http.Header
+	sendFunc HttpSendFunc
+	template *templatepkg.Template
+}
+
+func (c Client) NewRequest() Request {
+	return Request{sendFunc: c.send}
+}
+
+func (c Client) send(ctx context.Context, n Notification) error {
+	ctx = logging.WithLogger(ctx, logging.FromContext(ctx).Named("webhook"))
+
+	if c.url == "" {
+		return nil
+	}
+
+	var buf bytes.Buffer
+	if err := c.template.Execute(&buf, n); err != nil {
+		msg := "failed to populate template"
+		logging.FromContext(ctx).With("error", err).Error(msg)
+		return fmt.Errorf("%s: %w", msg, err)
+	}
+
+	req, err := http.NewRequest(http.MethodPost, c.url, &buf)
+	if err != nil {
+		msg := "failed to create request"
+		logging.FromContext(ctx).With("error", err).Error(msg)
+		return fmt.Errorf("%s: %w", msg, err)
+	}
+
+	req.Header = c.headers
+
+	resp, err := c.sendFunc(req)
+	if err != nil {
+		msg := "request failed"
+		logging.FromContext(ctx).With("error", err).Error(msg)
+		return fmt.Errorf("%s: %w", msg, err)
+	}
+	if resp != nil {
+		logging.FromContext(ctx).
+			With("status", resp.StatusCode).
+			Info("response status")
+	}
+
+	return nil
+}

src/pkg/webhook/notification.go

@@ -0,0 +1,27 @@
+/*
+Copyright 2022 Amazon.com, Inc. or its affiliates. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package webhook
+
+import "time"
+
+type Notification struct {
+	EventID    string
+	InstanceID string
+	Kind       string
+	NodeName   string
+	StartTime  time.Time
+}

src/pkg/webhook/request.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2022 Amazon.com, Inc. or its affiliates. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package webhook
+
+import (
+	"context"
+	"time"
+)
+
+type (
+	sendFuncType func(context.Context, Notification) error
+
+	Event interface {
+		EventID() string
+		Kind() string
+		StartTime() time.Time
+	}
+
+	Request struct {
+		sendFunc sendFuncType
+
+		Event      Event
+		InstanceID string
+		NodeName   string
+	}
+)
+
+func (r Request) Send(ctx context.Context) error {
+	return r.sendFunc(ctx, Notification{
+		EventID:    r.Event.EventID(),
+		InstanceID: r.InstanceID,
+		Kind:       r.Event.Kind(),
+		NodeName:   r.NodeName,
+		StartTime:  r.Event.StartTime(),
+	})
+}