From 75578aad61c1e9fae021223ece70cb83e3e2bcf2 Mon Sep 17 00:00:00 2001
From: Valentin Rothberg <rothberg@redhat.com>
Date: Sat, 22 Dec 2018 14:59:43 +0100
Subject: add container-init support
Add support for executing an init binary as PID 1 in a container to
forward signals and reap processes. When the `--init` flag is set for
podman-create or podman-run, the init binary is bind-mounted to
`/dev/init` in the container and "/dev/init --" is prepended to the
container's command.
The default base path of the container-init binary is `/usr/libexec/podman`
while the default binary is catatonit [1]. This default can be changed
permanently via the `init_path` field in the `libpod.conf` configuration
file (which is recommended for packaging) or temporarily via the
`--init-path` flag of podman-create and podman-run.
[1] https://github.com/openSUSE/catatonit
Fixes: #1670
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>
---
pkg/spec/createconfig.go | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
(limited to 'pkg')
diff --git a/pkg/spec/createconfig.go b/pkg/spec/createconfig.go
index 25f8cd7a1..ffc98e307 100644
--- a/pkg/spec/createconfig.go
+++ b/pkg/spec/createconfig.go
@@ -2,6 +2,7 @@ package createconfig
import (
"encoding/json"
+ "fmt"
"net"
"os"
"strconv"
@@ -145,6 +146,36 @@ func (c *CreateConfig) CreateBlockIO() (*spec.LinuxBlockIO, error) {
return c.createBlockIO()
}
+// AddContainerInitBinary adds the init binary specified by path iff the
+// container will run in a private PID namespace that is not shared with the
+// host or another pre-existing container, where an init-like process is
+// already running.
+//
+// Note that AddContainerInitBinary prepends "/dev/init" "--" to the command
+// to execute the bind-mounted binary as PID 1.
+func (c *CreateConfig) AddContainerInitBinary(path string) error {
+ if path == "" {
+ return fmt.Errorf("please specify a path to the container-init binary")
+ }
+ if !c.PidMode.IsPrivate() {
+ return fmt.Errorf("cannot add init binary as PID 1 (PID namespace isn't private)")
+ }
+ if c.Systemd {
+ return fmt.Errorf("cannot use container-init binary with systemd")
+ }
+ if _, err := os.Stat(path); os.IsNotExist(err) {
+ return errors.Wrap(err, "container-init binary not found on the host")
+ }
+ c.Command = append([]string{"/dev/init", "--"}, c.Command...)
+ c.Mounts = append(c.Mounts, spec.Mount{
+ Destination: "/dev/init",
+ Type: "bind",
+ Source: path,
+ Options: []string{"bind", "ro"},
+ })
+ return nil
+}
+
func processOptions(options []string) []string {
var (
foundrw, foundro bool
--
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