diff --git a/docs/reference/commandline/build.md b/docs/reference/commandline/build.md
index 2f8be4f7f9..c636a794d3 100644
--- a/docs/reference/commandline/build.md
+++ b/docs/reference/commandline/build.md
@@ -454,12 +454,12 @@ Specifying the `--isolation` flag without a value is the same as setting `--isol
### Add entries to container hosts file (--add-host)
-You can add other hosts into a container's `/etc/hosts` file by using one or
-more `--add-host` flags. This example adds a static address for a host named
-`docker`:
+You can add other hosts into a build container's `/etc/hosts` file by using one
+or more `--add-host` flags. This example adds static addresses for hosts named
+`my-hostname` and `my_hostname_v6`:
```console
-$ docker build --add-host docker:10.180.0.1 .
+$ docker build --add-host my_hostname=8.8.8.8 --add-host my_hostname_v6=2001:4860:4860::8888 .
```
If you need your build to connect to services running on the host, you can use
@@ -467,7 +467,15 @@ the special `host-gateway` value for `--add-host`. In the following example,
build containers resolve `host.docker.internal` to the host's gateway IP.
```console
-$ docker build --add-host host.docker.internal:host-gateway .
+$ docker build --add-host host.docker.internal=host-gateway .
+```
+
+You can wrap an IPv6 address in square brackets.
+`=` and `:` are both valid separators.
+Both formats in the following example are valid:
+
+```console
+$ docker build --add-host my-hostname:10.180.0.1 --add-host my-hostname_v6=[2001:4860:4860::8888] .
```
### Specifying target build stage (--target)
diff --git a/docs/reference/commandline/run.md b/docs/reference/commandline/run.md
index 0f7dc23691..9bb96ad45f 100644
--- a/docs/reference/commandline/run.md
+++ b/docs/reference/commandline/run.md
@@ -746,22 +746,28 @@ section of the Docker run reference page.
You can add other hosts into a container's `/etc/hosts` file by using one or
more `--add-host` flags. This example adds a static address for a host named
-`docker`:
+`my-hostname`:
```console
-$ docker run --add-host=docker:93.184.216.34 --rm -it alpine
+$ docker run --add-host=my-hostname=8.8.8.8 --rm -it alpine
-/ # ping docker
-PING docker (93.184.216.34): 56 data bytes
-64 bytes from 93.184.216.34: seq=0 ttl=37 time=93.052 ms
-64 bytes from 93.184.216.34: seq=1 ttl=37 time=92.467 ms
-64 bytes from 93.184.216.34: seq=2 ttl=37 time=92.252 ms
+/ # ping my-hostname
+PING my-hostname (8.8.8.8): 56 data bytes
+64 bytes from 8.8.8.8: seq=0 ttl=37 time=93.052 ms
+64 bytes from 8.8.8.8: seq=1 ttl=37 time=92.467 ms
+64 bytes from 8.8.8.8: seq=2 ttl=37 time=92.252 ms
^C
---- docker ping statistics ---
+--- my-hostname ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max = 92.209/92.495/93.052 ms
```
+You can wrap an IPv6 address in square brackets:
+
+```console
+$ docker run --add-host my-hostname=[2001:db8::33] --rm -it alpine
+```
+
The `--add-host` flag supports a special `host-gateway` value that resolves to
the internal IP address of the host. This is useful when you want containers to
connect to services running on the host machine.
@@ -779,11 +785,17 @@ $ echo "hello from host!" > ./hello
$ python3 -m http.server 8000
Serving HTTP on 0.0.0.0 port 8000 (http://0.0.0.0:8000/) ...
$ docker run \
- --add-host host.docker.internal:host-gateway \
+ --add-host host.docker.internal=host-gateway \
curlimages/curl -s host.docker.internal:8000/hello
hello from host!
```
+The `--add-host` flag also accepts a `:` separator, for example:
+
+```console
+$ docker run --add-host=my-hostname:8.8.8.8 --rm -it alpine
+```
+
### Set ulimits in container (--ulimit)
Since setting `ulimit` settings in a container requires extra privileges not
diff --git a/man/docker-build.1.md b/man/docker-build.1.md
index 341a3db3a1..a1088f352e 100644
--- a/man/docker-build.1.md
+++ b/man/docker-build.1.md
@@ -78,10 +78,10 @@ set as the **URL**, the repository is cloned locally and then sent as the contex
layers in tact, and one for the squashed version.
**--add-host** []
- Add a custom host-to-IP mapping (host:ip)
+ Add a custom host-to-IP mapping (host=ip, or host:ip)
- Add a line to /etc/hosts. The format is hostname:ip. The **--add-host**
-option can be set multiple times.
+ Add a line to /etc/hosts. The format is hostname=ip, or hostname:ip.
+ The **--add-host** option can be set multiple times.
**--build-arg** *variable*
name and value of a **buildarg**.
diff --git a/man/docker-run.1.md b/man/docker-run.1.md
index 7b6384c668..89e6b1f94b 100644
--- a/man/docker-run.1.md
+++ b/man/docker-run.1.md
@@ -121,10 +121,10 @@ executables expect) and pass along signals. The **-a** option can be set for
each of stdin, stdout, and stderr.
**--add-host**=[]
- Add a custom host-to-IP mapping (host:ip)
+ Add a custom host-to-IP mapping (host=ip, or host:ip)
- Add a line to /etc/hosts. The format is hostname:ip. The **--add-host**
-option can be set multiple times.
+ Add a line to /etc/hosts. The format is hostname=ip, or hostname:ip.
+ The **--add-host** option can be set multiple times.
**--annotation**=[]
Add an annotation to the container (passed through to the OCI runtime).
diff --git a/opts/hosts.go b/opts/hosts.go
index 7cdd1218f7..552ab6b4a5 100644
--- a/opts/hosts.go
+++ b/opts/hosts.go
@@ -161,21 +161,53 @@ func ParseTCPAddr(tryAddr string, defaultAddr string) (string, error) {
return fmt.Sprintf("tcp://%s%s", net.JoinHostPort(host, port), u.Path), nil
}
-// ValidateExtraHost validates that the specified string is a valid extrahost and returns it.
-// ExtraHost is in the form of name:ip where the ip has to be a valid ip (IPv4 or IPv6).
+// ValidateExtraHost validates that the specified string is a valid extrahost and
+// returns it. ExtraHost is in the form of name:ip or name=ip, where the ip has
+// to be a valid ip (IPv4 or IPv6). The address may be enclosed in square
+// brackets.
//
-// TODO(thaJeztah): remove client-side validation, and delegate to the API server.
+// For example:
+//
+// my-hostname:127.0.0.1
+// my-hostname:::1
+// my-hostname=::1
+// my-hostname:[::1]
+//
+// For compatibility with the API server, this function normalises the given
+// argument to use the ':' separator and strip square brackets enclosing the
+// address.
func ValidateExtraHost(val string) (string, error) {
- // allow for IPv6 addresses in extra hosts by only splitting on first ":"
- k, v, ok := strings.Cut(val, ":")
- if !ok || k == "" {
+ k, v, ok := strings.Cut(val, "=")
+ if !ok {
+ // allow for IPv6 addresses in extra hosts by only splitting on first ":"
+ k, v, ok = strings.Cut(val, ":")
+ }
+ // Check that a hostname was given, and that it doesn't contain a ":". (Colon
+ // isn't allowed in a hostname, along with many other characters. It's
+ // special-cased here because the API server doesn't know about '=' separators in
+ // '--add-host'. So, it'll split at the first colon and generate a strange error
+ // message.)
+ if !ok || k == "" || strings.Contains(k, ":") {
return "", fmt.Errorf("bad format for add-host: %q", val)
}
// Skip IPaddr validation for "host-gateway" string
if v != hostGatewayName {
+ // If the address is enclosed in square brackets, extract it (for IPv6, but
+ // permit it for IPv4 as well; we don't know the address family here, but it's
+ // unambiguous).
+ if len(v) > 2 && v[0] == '[' && v[len(v)-1] == ']' {
+ v = v[1 : len(v)-1]
+ }
+ // ValidateIPAddress returns the address in canonical form (for example,
+ // 0:0:0:0:0:0:0:1 -> ::1). But, stick with the original form, to avoid
+ // surprising a user who's expecting to see the address they supplied in the
+ // output of 'docker inspect' or '/etc/hosts'.
if _, err := ValidateIPAddress(v); err != nil {
return "", fmt.Errorf("invalid IP address in add-host: %q", v)
}
}
- return val, nil
+ // This result is passed directly to the API, the daemon doesn't accept the '='
+ // separator or an address enclosed in brackets. So, construct something it can
+ // understand.
+ return k + ":" + v, nil
}
diff --git a/opts/hosts_test.go b/opts/hosts_test.go
index 4da5f5625c..326d975564 100644
--- a/opts/hosts_test.go
+++ b/opts/hosts_test.go
@@ -2,8 +2,10 @@ package opts
import (
"fmt"
- "strings"
"testing"
+
+ "gotest.tools/v3/assert"
+ is "gotest.tools/v3/assert/cmp"
)
func TestParseHost(t *testing.T) {
@@ -146,32 +148,152 @@ func TestParseInvalidUnixAddrInvalid(t *testing.T) {
}
func TestValidateExtraHosts(t *testing.T) {
- valid := []string{
- `myhost:192.168.0.1`,
- `thathost:10.0.2.1`,
- `anipv6host:2003:ab34:e::1`,
- `ipv6local:::1`,
- `host.docker.internal:host-gateway`,
+ tests := []struct {
+ doc string
+ input string
+ expectedOut string // Expect output==input if not set.
+ expectedErr string // Expect success if not set.
+ }{
+ {
+ doc: "IPv4, colon sep",
+ input: `myhost:192.168.0.1`,
+ },
+ {
+ doc: "IPv4, eq sep",
+ input: `myhost=192.168.0.1`,
+ expectedOut: `myhost:192.168.0.1`,
+ },
+ {
+ doc: "Weird but permitted, IPv4 with brackets",
+ input: `myhost=[192.168.0.1]`,
+ expectedOut: `myhost:192.168.0.1`,
+ },
+ {
+ doc: "Host and domain",
+ input: `host.and.domain.invalid:10.0.2.1`,
+ },
+ {
+ doc: "IPv6, colon sep",
+ input: `anipv6host:2003:ab34:e::1`,
+ },
+ {
+ doc: "IPv6, colon sep, brackets",
+ input: `anipv6host:[2003:ab34:e::1]`,
+ expectedOut: `anipv6host:2003:ab34:e::1`,
+ },
+ {
+ doc: "IPv6, eq sep, brackets",
+ input: `anipv6host=[2003:ab34:e::1]`,
+ expectedOut: `anipv6host:2003:ab34:e::1`,
+ },
+ {
+ doc: "IPv6 localhost, colon sep",
+ input: `ipv6local:::1`,
+ },
+ {
+ doc: "IPv6 localhost, eq sep",
+ input: `ipv6local=::1`,
+ expectedOut: `ipv6local:::1`,
+ },
+ {
+ doc: "IPv6 localhost, eq sep, brackets",
+ input: `ipv6local=[::1]`,
+ expectedOut: `ipv6local:::1`,
+ },
+ {
+ doc: "IPv6 localhost, non-canonical, colon sep",
+ input: `ipv6local:0:0:0:0:0:0:0:1`,
+ },
+ {
+ doc: "IPv6 localhost, non-canonical, eq sep",
+ input: `ipv6local=0:0:0:0:0:0:0:1`,
+ expectedOut: `ipv6local:0:0:0:0:0:0:0:1`,
+ },
+ {
+ doc: "IPv6 localhost, non-canonical, eq sep, brackets",
+ input: `ipv6local=[0:0:0:0:0:0:0:1]`,
+ expectedOut: `ipv6local:0:0:0:0:0:0:0:1`,
+ },
+ {
+ doc: "host-gateway special case, colon sep",
+ input: `host.docker.internal:host-gateway`,
+ },
+ {
+ doc: "host-gateway special case, eq sep",
+ input: `host.docker.internal=host-gateway`,
+ expectedOut: `host.docker.internal:host-gateway`,
+ },
+ {
+ doc: "Bad address, colon sep",
+ input: `myhost:192.notanipaddress.1`,
+ expectedErr: `invalid IP address in add-host: "192.notanipaddress.1"`,
+ },
+ {
+ doc: "Bad address, eq sep",
+ input: `myhost=192.notanipaddress.1`,
+ expectedErr: `invalid IP address in add-host: "192.notanipaddress.1"`,
+ },
+ {
+ doc: "No sep",
+ input: `thathost-nosemicolon10.0.0.1`,
+ expectedErr: `bad format for add-host: "thathost-nosemicolon10.0.0.1"`,
+ },
+ {
+ doc: "Bad IPv6",
+ input: `anipv6host:::::1`,
+ expectedErr: `invalid IP address in add-host: "::::1"`,
+ },
+ {
+ doc: "Bad IPv6, trailing colons",
+ input: `ipv6local:::0::`,
+ expectedErr: `invalid IP address in add-host: "::0::"`,
+ },
+ {
+ doc: "Bad IPv6, missing close bracket",
+ input: `ipv6addr=[::1`,
+ expectedErr: `invalid IP address in add-host: "[::1"`,
+ },
+ {
+ doc: "Bad IPv6, missing open bracket",
+ input: `ipv6addr=::1]`,
+ expectedErr: `invalid IP address in add-host: "::1]"`,
+ },
+ {
+ doc: "Missing address, colon sep",
+ input: `myhost.invalid:`,
+ expectedErr: `invalid IP address in add-host: ""`,
+ },
+ {
+ doc: "Missing address, eq sep",
+ input: `myhost.invalid=`,
+ expectedErr: `invalid IP address in add-host: ""`,
+ },
+ {
+ doc: "IPv6 localhost, bad name",
+ input: `:=::1`,
+ expectedErr: `bad format for add-host: ":=::1"`,
+ },
+ {
+ doc: "No input",
+ input: ``,
+ expectedErr: `bad format for add-host: ""`,
+ },
}
- invalid := map[string]string{
- `myhost:192.notanipaddress.1`: `invalid IP`,
- `thathost-nosemicolon10.0.0.1`: `bad format`,
- `anipv6host:::::1`: `invalid IP`,
- `ipv6local:::0::`: `invalid IP`,
- }
-
- for _, extrahost := range valid {
- if _, err := ValidateExtraHost(extrahost); err != nil {
- t.Fatalf("ValidateExtraHost(`"+extrahost+"`) should succeed: error %v", err)
- }
- }
-
- for extraHost, expectedError := range invalid {
- if _, err := ValidateExtraHost(extraHost); err == nil {
- t.Fatalf("ValidateExtraHost(`%q`) should have failed validation", extraHost)
- } else if !strings.Contains(err.Error(), expectedError) {
- t.Fatalf("ValidateExtraHost(`%q`) error should contain %q", extraHost, expectedError)
+ for _, tc := range tests {
+ tc := tc
+ if tc.expectedOut == "" {
+ tc.expectedOut = tc.input
}
+ t.Run(tc.input, func(t *testing.T) {
+ actualOut, actualErr := ValidateExtraHost(tc.input)
+ if tc.expectedErr == "" {
+ assert.Check(t, is.Equal(tc.expectedOut, actualOut))
+ assert.NilError(t, actualErr)
+ } else {
+ assert.Check(t, actualOut == "")
+ assert.Check(t, is.Error(actualErr, tc.expectedErr))
+ }
+ })
}
}