feat: expose more instance metadata categories (#44)

.github/workflows/ci.yml

@@ -24,11 +24,13 @@ on:
     branches:
       - main
     paths:
+      - "**/*.go"
       - "*.go"
       - "go.mod"
       - "go.sum"
   pull_request:
     paths:
+      - "**/*.go"
       - "*.go"
       - "go.mod"
       - "go.sum"

.github/workflows/codeql.yml

@@ -25,9 +25,11 @@ on:
     branches:
       - main
     paths:
+      - "**/*.go"
       - "*.go"
   pull_request:
     paths:
+      - "**/*.go"
       - "*.go"
   schedule:
     - cron: "36 4 * * 6"

.github/workflows/docs.yml

@@ -21,6 +21,10 @@
 name: docs
 on:
   pull_request:
+    paths:
+      - ".github/workflows/docs.yml"
+      - "docs/**"
+      - "mkdocs.yml"
   push:
     tags:
       - "v*.*.*"
@@ -36,45 +40,53 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 0
+
       - name: Set up Python runtime
         uses: actions/setup-python@v4
         with:
           python-version: 3.x
+
       - name: Set up build cache
         uses: actions/cache@v3
         id: cache
         with:
           key: ${{ runner.os }}-${{ hashFiles('.cache/**') }}
           path: .cache
+
       - name: Install Python dependencies
         run: |
           pip install \
             "mkdocs-git-committers-plugin-2>=0.4.3" \
             "mkdocs-git-revision-date-localized-plugin>=1.0" \
             "mkdocs-minify-plugin>=0.3" \
             "mkdocs-redirects>=1.0"
+
       - name: Install MkDocs Insiders
         if: github.event.repository.fork == false
         env:
           GH_TOKEN: ${{ secrets.GH_MKDOCS }}
         run: |
           pip install git+https://${GH_TOKEN}@github.com/squidfunk/mkdocs-material-insiders.git
+
       - name: Build
         run: mkdocs build
         env:
           GH_TOKEN: ${{ secrets.GH_MKDOCS }}
+
       - name: HTML Test
         uses: wjdp/htmltest-action@master
         with:
           path: site
           config: htmltest.yml
+
       - name: Deploy documentation
         if: startsWith(github.ref, 'refs/tags/v')
         env:
           GH_TOKEN: ${{ secrets.GH_MKDOCS }}
         run: |
           mkdocs gh-deploy --force
           mkdocs --version
+
       - name: Set Custom Domain
         if: startsWith(github.ref, 'refs/tags/v')
         uses: octokit/[email protected]

pkg/imds/metadata.go

@@ -34,6 +34,9 @@ const (
 	pathIPv4            = "local-ipv4"
 	pathMacAddress      = "mac"
 	pathPlacementRegion = "placement/region"
+	pathPlacementAZ     = "placement/availability-zone"
+	pathInstanceID      = "instance-id"
+	pathHostname        = "hostname"
 )
 
 // MetadataClientAPI defines the API for interacting with the Amazon
@@ -60,6 +63,15 @@ type Metadata struct {
 
 	// VPC ID of where the EC2 instance was launched
 	VPC string
+
+	// AZ is the availability zone where the instance was launched
+	AZ string
+
+	// InstanceID is the unique ID of this instance
+	InstanceID string
+
+	// Hostname is the private IPv4 hostname of the launched instance
+	Hostname string
 }
 
 // NewFromAPI returns a new client from the provided IMDS API implementation
@@ -70,44 +82,39 @@ func NewFromAPI(api MetadataClientAPI) *Client {
 // InstanceMetadata attempts to retrieve useful metadata associated with
 // the current EC2 instance by querying IMDS
 func (c *Client) InstanceMetadata(ctx context.Context) (Metadata, error) {
-	region, err := region(ctx, c.api)
-	if err != nil {
+	md := Metadata{}
+
+	var err error
+	if md.Region, err = get(ctx, c.api, pathPlacementRegion); err != nil {
 		return Metadata{}, err
 	}
 
-	ipv4, err := ipv4(ctx, c.api)
-	if err != nil {
+	if md.IPv4, err = get(ctx, c.api, pathIPv4); err != nil {
 		return Metadata{}, err
 	}
 
-	vpcID, err := vpc(ctx, c.api)
-	if err != nil {
+	if md.VPC, err = vpc(ctx, c.api); err != nil {
 		return Metadata{}, err
 	}
 
-	return Metadata{
-		Region: region,
-		IPv4:   ipv4,
-		VPC:    vpcID,
-	}, nil
-}
+	if md.AZ, err = get(ctx, c.api, pathPlacementAZ); err != nil {
+		return Metadata{}, err
+	}
 
-func region(ctx context.Context, api MetadataClientAPI) (string, error) {
-	out, err := api.GetMetadata(ctx, &awsimds.GetMetadataInput{
-		Path: pathPlacementRegion,
-	})
-	if err != nil {
-		return "", err
+	if md.InstanceID, err = get(ctx, c.api, pathInstanceID); err != nil {
+		return Metadata{}, err
 	}
-	defer out.Content.Close()
 
-	data, _ := ioutil.ReadAll(out.Content)
-	return string(data), nil
+	if md.Hostname, err = get(ctx, c.api, pathHostname); err != nil {
+		return Metadata{}, err
+	}
+
+	return md, nil
 }
 
-func ipv4(ctx context.Context, api MetadataClientAPI) (string, error) {
+func get(ctx context.Context, api MetadataClientAPI, path string) (string, error) {
 	out, err := api.GetMetadata(ctx, &awsimds.GetMetadataInput{
-		Path: pathIPv4,
+		Path: path,
 	})
 	if err != nil {
 		return "", err
@@ -119,24 +126,15 @@ func ipv4(ctx context.Context, api MetadataClientAPI) (string, error) {
 }
 
 func vpc(ctx context.Context, api MetadataClientAPI) (string, error) {
-	mac, err := api.GetMetadata(ctx, &awsimds.GetMetadataInput{
-		Path: pathMacAddress,
-	})
+	mac, err := get(ctx, api, pathMacAddress)
 	if err != nil {
 		return "", err
 	}
-	defer mac.Content.Close()
-	md, _ := ioutil.ReadAll(mac.Content)
 
-	// Use the MAC address to retrieve the VPC associated with the EC2 instance
-	out, err := api.GetMetadata(ctx, &awsimds.GetMetadataInput{
-		Path: fmt.Sprintf("network/interfaces/macs/%s/vpc-id", string(md)),
-	})
+	vpc, err := get(ctx, api, fmt.Sprintf("network/interfaces/macs/%s/vpc-id", mac))
 	if err != nil {
 		return "", err
 	}
-	defer mac.Content.Close()
-	data, _ := ioutil.ReadAll(out.Content)
 
-	return string(data), nil
+	return vpc, nil
 }

pkg/imds/metadata_test.go

@@ -51,4 +51,7 @@ func TestIntegration_InstanceMetadata(t *testing.T) {
 	assert.Equal(t, aemm.ValueLocalIPv4, metadata.IPv4)
 	assert.Equal(t, aemm.ValuePlacementRegion, metadata.Region)
 	assert.Equal(t, aemm.ValueNetworkInterfaces0VPCID, metadata.VPC)
+	assert.Equal(t, aemm.ValuePlacementAvailabilityZone, metadata.AZ)
+	assert.Equal(t, aemm.ValueInstanceID, metadata.InstanceID)
+	assert.Equal(t, aemm.ValueHostname, metadata.Hostname)
 }