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Misleading 404 logs in IMDS mode when querying EC2 Metadata without a public IP #1058

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merged 2 commits into from
Nov 21, 2024
Merged

Misleading 404 logs in IMDS mode when querying EC2 Metadata without a public IP #1058

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fef7353
assume public ip and hostname ec2 metadata can be absent
xabinapal Aug 29, 2024
62870ab
add ec2metadata new tests to check for optional paths
xabinapal Aug 29, 2024
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28 changes: 16 additions & 12 deletions pkg/ec2metadata/ec2metadata.go
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Original file line number Diff line number Diff line change
Expand Up @@ -218,7 +218,7 @@ func (e *Service) GetASGTargetLifecycleState() (state string, err error) {
}

// GetMetadataInfo generic function for retrieving ec2 metadata
func (e *Service) GetMetadataInfo(path string) (info string, err error) {
func (e *Service) GetMetadataInfo(path string, allowMissing bool) (info string, err error) {
metadataInfo := ""
resp, err := e.Request(path)
if err != nil {
Expand All @@ -232,8 +232,12 @@ func (e *Service) GetMetadataInfo(path string) (info string, err error) {
}
metadataInfo = string(body)
if resp.StatusCode < 200 || resp.StatusCode >= 300 {
log.Info().Msgf("Metadata response status code: %d. Body: %s", resp.StatusCode, metadataInfo)
return "", fmt.Errorf("Metadata request received http status code: %d", resp.StatusCode)
if resp.StatusCode != 404 || !allowMissing {
log.Info().Msgf("Metadata response status code: %d. Body: %s", resp.StatusCode, metadataInfo)
return "", fmt.Errorf("Metadata request received http status code: %d", resp.StatusCode)
} else {
return "", nil
}
}
}
return metadataInfo, nil
Expand Down Expand Up @@ -351,26 +355,26 @@ func retry(attempts int, sleep time.Duration, httpReq func() (*http.Response, er
// GetNodeMetadata attempts to gather additional ec2 instance information from the metadata service
func (e *Service) GetNodeMetadata() NodeMetadata {
metadata := NodeMetadata{}
identityDoc, err := e.GetMetadataInfo(IdentityDocPath)
identityDoc, err := e.GetMetadataInfo(IdentityDocPath, false)
if err != nil {
log.Err(err).Msg("Unable to fetch metadata from IMDS")
return metadata
}
err = json.NewDecoder(strings.NewReader(identityDoc)).Decode(&metadata)
if err != nil {
log.Warn().Msg("Unable to fetch instance identity document from ec2 metadata")
metadata.InstanceID, _ = e.GetMetadataInfo(InstanceIDPath)
metadata.InstanceType, _ = e.GetMetadataInfo(InstanceTypePath)
metadata.LocalIP, _ = e.GetMetadataInfo(LocalIPPath)
metadata.AvailabilityZone, _ = e.GetMetadataInfo(AZPlacementPath)
metadata.InstanceID, _ = e.GetMetadataInfo(InstanceIDPath, false)
metadata.InstanceType, _ = e.GetMetadataInfo(InstanceTypePath, false)
metadata.LocalIP, _ = e.GetMetadataInfo(LocalIPPath, false)
metadata.AvailabilityZone, _ = e.GetMetadataInfo(AZPlacementPath, false)
if len(metadata.AvailabilityZone) > 1 {
metadata.Region = metadata.AvailabilityZone[0 : len(metadata.AvailabilityZone)-1]
}
}
metadata.InstanceLifeCycle, _ = e.GetMetadataInfo(InstanceLifeCycle)
metadata.LocalHostname, _ = e.GetMetadataInfo(LocalHostnamePath)
metadata.PublicHostname, _ = e.GetMetadataInfo(PublicHostnamePath)
metadata.PublicIP, _ = e.GetMetadataInfo(PublicIPPath)
metadata.InstanceLifeCycle, _ = e.GetMetadataInfo(InstanceLifeCycle, false)
metadata.LocalHostname, _ = e.GetMetadataInfo(LocalHostnamePath, false)
metadata.PublicHostname, _ = e.GetMetadataInfo(PublicHostnamePath, true)
metadata.PublicIP, _ = e.GetMetadataInfo(PublicIPPath, true)

log.Info().Interface("metadata", metadata).Msg("Startup Metadata Retrieved")

Expand Down
58 changes: 54 additions & 4 deletions pkg/ec2metadata/ec2metadata_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -609,16 +609,66 @@ func TestGetMetadataServiceRequest404(t *testing.T) {
// Use URL from our local test server
imds := ec2metadata.New(server.URL, 1)

_, err := imds.GetMetadataInfo(requestPath)
_, err := imds.GetMetadataInfo(requestPath, false)

h.Assert(t, err != nil, "Expected error to be nil but it was not")
h.Assert(t, err != nil, "Error expected because request errored with 404")
}

func TestGetMetadataServiceRequest404AllowMissing(t *testing.T) {
var requestPath string = "/latest/meta-data/instance-type"

server := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
rw.Header().Add("X-aws-ec2-metadata-token-ttl-seconds", "100")
if req.URL.String() == "/latest/api/token" {
rw.WriteHeader(200)
_, err := rw.Write([]byte(`token`))
h.Ok(t, err)
return
}
h.Equals(t, req.Header.Get("X-aws-ec2-metadata-token"), "token")
h.Equals(t, req.URL.String(), requestPath)
rw.WriteHeader(404)
}))
defer server.Close()

// Use URL from our local test server
imds := ec2metadata.New(server.URL, 1)

_, err := imds.GetMetadataInfo(requestPath, true)

h.Assert(t, err == nil, "Expected error to be nil but it was not")
}

func TestGetMetadataServiceRequest500AllowMissing(t *testing.T) {
var requestPath string = "/latest/meta-data/instance-type"

server := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
rw.Header().Add("X-aws-ec2-metadata-token-ttl-seconds", "100")
if req.URL.String() == "/latest/api/token" {
rw.WriteHeader(200)
_, err := rw.Write([]byte(`token`))
h.Ok(t, err)
return
}
h.Equals(t, req.Header.Get("X-aws-ec2-metadata-token"), "token")
h.Equals(t, req.URL.String(), requestPath)
rw.WriteHeader(500)
}))
defer server.Close()

// Use URL from our local test server
imds := ec2metadata.New(server.URL, 1)

_, err := imds.GetMetadataInfo(requestPath, true)

h.Assert(t, err != nil, "Error expected because request errored with 500")
}

func TestGetMetadataServiceRequestFailure(t *testing.T) {
// Use URL from our local test server
imds := ec2metadata.New("/some-path-that-will-error", 1)

_, err := imds.GetMetadataInfo("/latest/meta-data/instance-type")
_, err := imds.GetMetadataInfo("/latest/meta-data/instance-type", false)
h.Assert(t, err != nil, "Error expected because no server should be running")
}

Expand All @@ -643,7 +693,7 @@ func TestGetMetadataServiceSuccess(t *testing.T) {
// Use URL from our local test server
imds := ec2metadata.New(server.URL, 1)

resp, err := imds.GetMetadataInfo(requestPath)
resp, err := imds.GetMetadataInfo(requestPath, false)

h.Ok(t, err)
h.Equals(t, `x1.32xlarge`, resp)
Expand Down
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