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write HostAliases to hosts file #45148

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merged 1 commit into from
May 1, 2017
Merged

write HostAliases to hosts file #45148

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19 changes: 13 additions & 6 deletions pkg/kubelet/kubelet_pods.go
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Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,8 @@ func makeMounts(pod *v1.Pod, podDir string, container *v1.Container, hostName, h
})
}
if mountEtcHostsFile {
hostsMount, err := makeHostsMount(podDir, podIP, hostName, hostDomain)
hostAliases := pod.Spec.HostAliases
hostsMount, err := makeHostsMount(podDir, podIP, hostName, hostDomain, hostAliases)
if err != nil {
return nil, err
}
Expand All @@ -192,9 +193,9 @@ func makeMounts(pod *v1.Pod, podDir string, container *v1.Container, hostName, h

// makeHostsMount makes the mountpoint for the hosts file that the containers
// in a pod are injected with.
func makeHostsMount(podDir, podIP, hostName, hostDomainName string) (*kubecontainer.Mount, error) {
func makeHostsMount(podDir, podIP, hostName, hostDomainName string, hostAliases []v1.HostAlias) (*kubecontainer.Mount, error) {
hostsFilePath := path.Join(podDir, "etc-hosts")
if err := ensureHostsFile(hostsFilePath, podIP, hostName, hostDomainName); err != nil {
if err := ensureHostsFile(hostsFilePath, podIP, hostName, hostDomainName, hostAliases); err != nil {
return nil, err
}
return &kubecontainer.Mount{
Expand All @@ -208,17 +209,17 @@ func makeHostsMount(podDir, podIP, hostName, hostDomainName string) (*kubecontai

// ensureHostsFile ensures that the given host file has an up-to-date ip, host
// name, and domain name.
func ensureHostsFile(fileName, hostIP, hostName, hostDomainName string) error {
func ensureHostsFile(fileName, hostIP, hostName, hostDomainName string, hostAliases []v1.HostAlias) error {
if _, err := os.Stat(fileName); os.IsExist(err) {
glog.V(4).Infof("kubernetes-managed etc-hosts file exits. Will not be recreated: %q", fileName)
return nil
}
content := hostsFileContent(hostIP, hostName, hostDomainName)
content := hostsFileContent(hostIP, hostName, hostDomainName, hostAliases)
return ioutil.WriteFile(fileName, content, 0644)
}

// hostsFileContent is the content of the managed etc hosts
func hostsFileContent(hostIP, hostName, hostDomainName string) []byte {
func hostsFileContent(hostIP, hostName, hostDomainName string, hostAliases []v1.HostAlias) []byte {
var buffer bytes.Buffer
buffer.WriteString("# Kubernetes-managed hosts file.\n")
buffer.WriteString("127.0.0.1\tlocalhost\n") // ipv4 localhost
Expand All @@ -232,6 +233,12 @@ func hostsFileContent(hostIP, hostName, hostDomainName string) []byte {
} else {
buffer.WriteString(fmt.Sprintf("%s\t%s\n", hostIP, hostName))
}
// write each IP/hostname pair as an entry into hosts file
for _, hostAlias := range hostAliases {
for _, hostname := range hostAlias.Hostnames {
buffer.WriteString(fmt.Sprintf("%s\t%s\n", hostAlias.IP, hostname))
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Comment that this was previously validated to be a valid IP address and hostname?

}
}
return buffer.Bytes()
}

Expand Down
49 changes: 48 additions & 1 deletion pkg/kubelet/kubelet_pods_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -119,12 +119,14 @@ func TestHostsFileContent(t *testing.T) {
hostIP string
hostName string
hostDomainName string
hostAliases []v1.HostAlias
expectedContent string
}{
{
"123.45.67.89",
"podFoo",
"",
[]v1.HostAlias{},
`# Kubernetes-managed hosts file.
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
Expand All @@ -139,6 +141,7 @@ fe00::2 ip6-allrouters
"203.0.113.1",
"podFoo",
"domainFoo",
[]v1.HostAlias{},
`# Kubernetes-managed hosts file.
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
Expand All @@ -147,12 +150,56 @@ fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
203.0.113.1 podFoo.domainFoo podFoo
`,
},
{
"203.0.113.1",
"podFoo",
"domainFoo",
[]v1.HostAlias{
{IP: "123.45.67.89", Hostnames: []string{"foo", "bar", "baz"}},
},
`# Kubernetes-managed hosts file.
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
203.0.113.1 podFoo.domainFoo podFoo
123.45.67.89 foo
123.45.67.89 bar
123.45.67.89 baz
`,
},
{
"203.0.113.1",
"podFoo",
"domainFoo",
[]v1.HostAlias{
{IP: "123.45.67.89", Hostnames: []string{"foo", "bar", "baz"}},
{IP: "456.78.90.123", Hostnames: []string{"park", "doo", "boo"}},
},
`# Kubernetes-managed hosts file.
127.0.0.1 localhost
::1 localhost ip6-localhost ip6-loopback
fe00::0 ip6-localnet
fe00::0 ip6-mcastprefix
fe00::1 ip6-allnodes
fe00::2 ip6-allrouters
203.0.113.1 podFoo.domainFoo podFoo
123.45.67.89 foo
123.45.67.89 bar
123.45.67.89 baz
456.78.90.123 park
456.78.90.123 doo
456.78.90.123 boo
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should we add validation that there are not duplicate hostnames in case someone adds:

[]v1.HostAlias{
	{IP: "123.45.67.89", Hostnames: []string{"foo", "bar"}},
	{IP: "456.78.90.123", Hostnames: []string{"foo", "bar"}},
}

which results in

123.45.67.89	foo
123.45.67.89	bar
456.78.90.123	foo
456.78.90.123	bar

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And shouldn't we validate for proper IPv4 IPs? :-)

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78d6662

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I think dups is fine - it's your own fault.

`,
},
}

for _, testCase := range testCases {
actualContent := string(hostsFileContent(testCase.hostIP, testCase.hostName, testCase.hostDomainName))
actualContent := string(hostsFileContent(testCase.hostIP, testCase.hostName, testCase.hostDomainName, testCase.hostAliases))
assert.Equal(t, testCase.expectedContent, actualContent, "hosts file content not expected")
}
}
Expand Down