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Allow FQDN lookup functions to take context #199

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merged 8 commits into from
Feb 1, 2024
Merged

Allow FQDN lookup functions to take context #199

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fd1ad25
Pass context to FQDN lookup functions
ycombinator Jan 25, 2024
01b75c6
Adding CHANGELOG entry
ycombinator Jan 25, 2024
6eea02f
Update test
ycombinator Jan 25, 2024
2b70234
Closer replacement
ycombinator Jan 25, 2024
b05739a
Include timeout test case
ycombinator Jan 25, 2024
f64eb1b
Tighten regex
ycombinator Jan 25, 2024
8ef547d
Add FQDNWithContext functions to prevent breaking change
ycombinator Jan 25, 2024
ee500ea
Fix call
ycombinator Jan 31, 2024
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3 changes: 3 additions & 0 deletions .changelog/199.txt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
```release-note:enhancement
Allow FQDN lookup functions to take a context.
```
7 changes: 6 additions & 1 deletion providers/aix/host_aix_ppc64.go
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ package aix
import "C"

import (
"context"
"errors"
"fmt"
"os"
Expand Down Expand Up @@ -128,8 +129,12 @@ func (*host) Memory() (*types.HostMemoryInfo, error) {
return &mem, nil
}

func (h *host) FQDNWithContext(ctx context.Context) (string, error) {
return shared.FQDNWithContext(ctx)
}

func (h *host) FQDN() (string, error) {
return shared.FQDN()
return h.FQDNWithContext(context.Background())
}

func newHost() (*host, error) {
Expand Down
7 changes: 6 additions & 1 deletion providers/darwin/host_darwin.go
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Expand Up @@ -20,6 +20,7 @@
package darwin

import (
"context"
"errors"
"fmt"
"os"
Expand Down Expand Up @@ -139,8 +140,12 @@ func (h *host) Memory() (*types.HostMemoryInfo, error) {
return &mem, nil
}

func (h *host) FQDNWithContext(ctx context.Context) (string, error) {
return shared.FQDNWithContext(ctx)
}

func (h *host) FQDN() (string, error) {
return shared.FQDN()
return h.FQDNWithContext(context.Background())
}

func (h *host) LoadAverage() (*types.LoadAverageInfo, error) {
Expand Down
12 changes: 10 additions & 2 deletions providers/linux/host_fqdn_integration_docker_linux_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,10 @@
package linux

import (
"context"
"fmt"
"testing"
"time"

"github.com/stretchr/testify/require"
)
Expand All @@ -32,7 +34,10 @@ func TestHost_FQDN_set(t *testing.T) {
t.Fatal(fmt.Errorf("could not get host information: %w", err))
}

gotFQDN, err := host.FQDN()
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()

gotFQDN, err := host.FQDNWithContext(ctx)
require.NoError(t, err)
if gotFQDN != wantFQDN {
t.Errorf("got FQDN %q, want: %q", gotFQDN, wantFQDN)
Expand All @@ -45,7 +50,10 @@ func TestHost_FQDN_not_set(t *testing.T) {
t.Fatal(fmt.Errorf("could not get host information: %w", err))
}

gotFQDN, err := host.FQDN()
ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()

gotFQDN, err := host.FQDNWithContext(ctx)
require.NoError(t, err)
hostname := host.Info().Hostname
if gotFQDN != hostname {
Expand Down
7 changes: 6 additions & 1 deletion providers/linux/host_linux.go
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Expand Up @@ -18,6 +18,7 @@
package linux

import (
"context"
"errors"
"fmt"
"io/ioutil"
Expand Down Expand Up @@ -73,8 +74,12 @@ func (h *host) Memory() (*types.HostMemoryInfo, error) {
return parseMemInfo(content)
}

func (h *host) FQDNWithContext(ctx context.Context) (string, error) {
return shared.FQDNWithContext(ctx)
}

func (h *host) FQDN() (string, error) {
return shared.FQDN()
return h.FQDNWithContext(context.Background())
}

// VMStat reports data from /proc/vmstat on linux.
Expand Down
20 changes: 13 additions & 7 deletions providers/shared/fqdn.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,13 +20,14 @@
package shared

import (
"context"
"fmt"
"net"
"os"
"strings"
)

// FQDN attempts to lookup the host's fully-qualified domain name and returns it.
// FQDNWithContext attempts to lookup the host's fully-qualified domain name and returns it.
// It does so using the following algorithm:
//
// 1. It gets the hostname from the OS. If this step fails, it returns an error.
Expand All @@ -40,18 +41,23 @@ import (
//
// 4. If steps 2 and 3 both fail, an empty string is returned as the FQDN along with
// errors from those steps.
func FQDN() (string, error) {
func FQDNWithContext(ctx context.Context) (string, error) {
hostname, err := os.Hostname()
if err != nil {
return "", fmt.Errorf("could not get hostname to look for FQDN: %w", err)
}

return fqdn(hostname)
return fqdn(ctx, hostname)
}

// FQDN just calls FQDNWithContext with a background context.
func FQDN() (string, error) {
return FQDNWithContext(context.Background())
}

func fqdn(hostname string) (string, error) {
func fqdn(ctx context.Context, hostname string) (string, error) {
var errs error
cname, err := net.LookupCNAME(hostname)
cname, err := net.DefaultResolver.LookupCNAME(ctx, hostname)
if err != nil {
errs = fmt.Errorf("could not get FQDN, all methods failed: failed looking up CNAME: %w",
err)
Expand All @@ -60,13 +66,13 @@ func fqdn(hostname string) (string, error) {
return strings.ToLower(strings.TrimSuffix(cname, ".")), nil
}

ips, err := net.LookupIP(hostname)
ips, err := net.DefaultResolver.LookupIP(ctx, "ip", hostname)
if err != nil {
errs = fmt.Errorf("%s: failed looking up IP: %w", errs, err)
}

for _, ip := range ips {
names, err := net.LookupAddr(ip.String())
names, err := net.DefaultResolver.LookupAddr(ctx, ip.String())
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The type of ips here changed from []net.IP to []net.IPAddr which doesn't have the same implementation of String(), since net.IPAddr embeds IP and extends it with a zone.

If you want the exact same conversion as before you want to call ip.IP.String() I think.

func (a *IPAddr) String() string {
	if a == nil {
		return "<nil>"
	}
	ip := ipEmptyString(a.IP)
	if a.Zone != "" {
		return ip + "%" + a.Zone
	}
	return ip
}

The original call to net.LookupIP stripped off the IPv6 zone: https://cs.opensource.google/go/go/+/refs/tags/go1.21.6:src/net/lookup.go;l=195

// LookupIP looks up host using the local resolver.
// It returns a slice of that host's IPv4 and IPv6 addresses.
func LookupIP(host string) ([]IP, error) {
	addrs, err := DefaultResolver.LookupIPAddr(context.Background(), host)
	if err != nil {
		return nil, err
	}
	ips := make([]IP, len(addrs))
	for i, ia := range addrs {
		ips[i] = ia.IP
	}
	return ips, nil
}

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The type of ips here changed from []net.IP to []net.IPAddr...

Are you sure? Before, ips was initialized as:

ips, err := net.LookupIP(hostname)

Now, it's initialized as:

ips, err := net.DefaultResolver.LookupIP(ctx, "ip", hostname)

In both cases, the type of ips is the same: []IP.

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Ah you are right for some reason I ended up focusing on LookupIPAddr as if it were called early, I think this was because net.LookupIP calls LookupIPAddr but func (r *Resolver) LookupIP does something else.

I don't have enough brainpower left for the day or network knowledge to know if that is significant, I was trying to quickly check if this worked the same as it did before.

if err != nil || len(names) == 0 {
continue
}
Expand Down
32 changes: 27 additions & 5 deletions providers/shared/fqdn_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,10 @@
package shared

import (
"context"
"fmt"
"testing"
"time"

"github.com/stretchr/testify/require"
)
Expand All @@ -31,6 +33,7 @@ func TestFQDN(t *testing.T) {
osHostname string
expectedFQDN string
expectedErrRegex string
timeout time.Duration
}{
// This test case depends on network, particularly DNS,
// being available. If it starts to fail often enough
Expand All @@ -44,23 +47,37 @@ func TestFQDN(t *testing.T) {
"long_nonexistent_hostname": {
osHostname: "foo.bar.elastic.co",
expectedFQDN: "",
expectedErrRegex: makeErrorRegex("foo.bar.elastic.co"),
expectedErrRegex: makeErrorRegex("foo.bar.elastic.co", false),
},
"short_nonexistent_hostname": {
osHostname: "foobarbaz",
expectedFQDN: "",
expectedErrRegex: makeErrorRegex("foobarbaz"),
expectedErrRegex: makeErrorRegex("foobarbaz", false),
},
"long_mixed_case_hostname": {
osHostname: "eLaSTic.co",
expectedFQDN: "elastic.co",
expectedErrRegex: "",
},
"nonexistent_timeout": {
osHostname: "foobarbaz",
expectedFQDN: "",
expectedErrRegex: makeErrorRegex("foobarbaz", true),
timeout: 1 * time.Millisecond,
},
}

for name, test := range tests {
t.Run(name, func(t *testing.T) {
actualFQDN, err := fqdn(test.osHostname)
timeout := test.timeout
if timeout == 0 {
timeout = 10 * time.Second
}

ctx, cancel := context.WithTimeout(context.Background(), timeout)
defer cancel()

actualFQDN, err := fqdn(ctx, test.osHostname)
require.Equal(t, test.expectedFQDN, actualFQDN)

if test.expectedErrRegex == "" {
Expand All @@ -72,11 +89,16 @@ func TestFQDN(t *testing.T) {
}
}

func makeErrorRegex(osHostname string) string {
func makeErrorRegex(osHostname string, withTimeout bool) string {
timeoutStr := ""
if withTimeout {
timeoutStr = ": i/o timeout"
}

return fmt.Sprintf(
"could not get FQDN, all methods failed: "+
"failed looking up CNAME: lookup %s.*: "+
"failed looking up IP: lookup %s.*",
"failed looking up IP: lookup %s"+timeoutStr,
osHostname,
osHostname,
)
Expand Down
7 changes: 6 additions & 1 deletion providers/windows/host_windows.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,7 @@
package windows

import (
"context"
"errors"
"fmt"
"os"
Expand Down Expand Up @@ -84,7 +85,7 @@ func (h *host) Memory() (*types.HostMemoryInfo, error) {
}, nil
}

func (h *host) FQDN() (string, error) {
func (h *host) FQDNWithContext(_ context.Context) (string, error) {
fqdn, err := getComputerNameEx(stdwindows.ComputerNamePhysicalDnsFullyQualified)
if err != nil {
return "", fmt.Errorf("could not get windows FQDN: %s", err)
Expand All @@ -93,6 +94,10 @@ func (h *host) FQDN() (string, error) {
return strings.ToLower(strings.TrimSuffix(fqdn, ".")), nil
}

func (h *host) FQDN() (string, error) {
return h.FQDNWithContext(context.Background())
}

func newHost() (*host, error) {
h := &host{}
r := &reader{}
Expand Down
11 changes: 9 additions & 2 deletions types/host.go
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Expand Up @@ -17,7 +17,10 @@

package types

import "time"
import (
"context"
"time"
)

// Host is the interface that wraps methods for returning Host stats
// It may return partial information if the provider
Expand All @@ -27,7 +30,11 @@ type Host interface {
Info() HostInfo
Memory() (*HostMemoryInfo, error)

// FQDN returns the fully-qualified domain name of the host, lowercased.
// FQDNWithContext returns the fully-qualified domain name of the host, lowercased.
FQDNWithContext(ctx context.Context) (string, error)

// FQDN calls FQDNWithContext with a background context.
// Deprecated: Use FQDNWithContext instead.
FQDN() (string, error)
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This is a breaking change to the API. I suggest adding an FQDNWithContext(context.Context) unless we are prepared to rollout a github.com/elastic/go-sysinfo/v2.

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Done in 8ef547d.

}

Expand Down
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