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package links // import "github.com/docker/docker/daemon/links"
import (
"fmt"
"path"
"strings"
"github.com/docker/go-connections/nat"
)
// Link struct holds information about parent/child linked container
type Link struct {
// Parent container IP address
ParentIP string
// Child container IP address
ChildIP string
// Link name
Name string
// Child environments variables
ChildEnvironment []string
// Child exposed ports
Ports []nat.Port
}
// NewLink initializes a new Link struct with the provided options.
func NewLink(parentIP, childIP, name string, env []string, exposedPorts map[nat.Port]struct{}) *Link {
var (
i int
ports = make([]nat.Port, len(exposedPorts))
)
for p := range exposedPorts {
ports[i] = p
i++
}
return &Link{
Name: name,
ChildIP: childIP,
ParentIP: parentIP,
ChildEnvironment: env,
Ports: ports,
}
}
// ToEnv creates a string's slice containing child container information in
// the form of environment variables which will be later exported on container
// startup.
func (l *Link) ToEnv() []string {
env := []string{}
_, n := path.Split(l.Name)
alias := strings.ReplaceAll(strings.ToUpper(n), "-", "_")
if p := l.getDefaultPort(); p != nil {
env = append(env, fmt.Sprintf("%s_PORT=%s://%s:%s", alias, p.Proto(), l.ChildIP, p.Port()))
}
// sort the ports so that we can bulk the continuous ports together
nat.Sort(l.Ports, func(ip, jp nat.Port) bool {
// If the two ports have the same number, tcp takes priority
// Sort in desc order
return ip.Int() < jp.Int() || (ip.Int() == jp.Int() && strings.ToLower(ip.Proto()) == "tcp")
})
for i := 0; i < len(l.Ports); {
p := l.Ports[i]
j := nextContiguous(l.Ports, p.Int(), i)
if j > i+1 {
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_START=%s://%s:%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto(), l.ChildIP, p.Port()))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_ADDR=%s", alias, p.Port(), strings.ToUpper(p.Proto()), l.ChildIP))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PROTO=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto()))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT_START=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Port()))
q := l.Ports[j]
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_END=%s://%s:%s", alias, p.Port(), strings.ToUpper(q.Proto()), q.Proto(), l.ChildIP, q.Port()))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT_END=%s", alias, p.Port(), strings.ToUpper(q.Proto()), q.Port()))
i = j + 1
continue
} else {
i++
}
}
for _, p := range l.Ports {
env = append(env, fmt.Sprintf("%s_PORT_%s_%s=%s://%s:%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto(), l.ChildIP, p.Port()))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_ADDR=%s", alias, p.Port(), strings.ToUpper(p.Proto()), l.ChildIP))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PORT=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Port()))
env = append(env, fmt.Sprintf("%s_PORT_%s_%s_PROTO=%s", alias, p.Port(), strings.ToUpper(p.Proto()), p.Proto()))
}
// Load the linked container's name into the environment
env = append(env, fmt.Sprintf("%s_NAME=%s", alias, l.Name))
if l.ChildEnvironment != nil {
for _, v := range l.ChildEnvironment {
name, val, ok := strings.Cut(v, "=")
if !ok {
continue
}
// Ignore a few variables that are added during docker build (and not really relevant to linked containers)
if name == "HOME" || name == "PATH" {
continue
}
env = append(env, fmt.Sprintf("%s_ENV_%s=%s", alias, name, val))
}
}
return env
}
func nextContiguous(ports []nat.Port, value int, index int) int {
if index+1 == len(ports) {
return index
}
for i := index + 1; i < len(ports); i++ {
if ports[i].Int() > value+1 {
return i - 1
}
value++
}
return len(ports) - 1
}
// Default port rules
func (l *Link) getDefaultPort() *nat.Port {
var p nat.Port
i := len(l.Ports)
if i == 0 {
return nil
} else if i > 1 {
nat.Sort(l.Ports, func(ip, jp nat.Port) bool {
// If the two ports have the same number, tcp takes priority
// Sort in desc order
return ip.Int() < jp.Int() || (ip.Int() == jp.Int() && strings.ToLower(ip.Proto()) == "tcp")
})
}
p = l.Ports[0]
return &p
}
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