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Remove outdated kill method to stop sidecar
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@kvij
kvij committed Sep 21, 2023
1 parent c13e15c commit 1e813c4
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25 changes: 1 addition & 24 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -19,33 +19,10 @@ When the application exits, unless `NEVER_KILL_ISTIO_ON_FAILURE` has been set an
| `SCUTTLE_LOGGING` | If provided and set to `true`, `scuttle` will log various steps to the console which is helpful for debugging |
| `START_WITHOUT_ENVOY` | If provided and set to `true`, `scuttle` will not wait for envoy to be LIVE before starting the main application. However, it will still instruct envoy to exit. |
| `WAIT_FOR_ENVOY_TIMEOUT` | If provided and set to a valid `time.Duration` string greater than 0 seconds, `scuttle` will wait for that amount of time before starting the main application. By default, it will wait indefinitely. If `QUIT_WITHOUT_ENVOY_TIMEOUT` is set as well, it will take precedence over this variable |
| `ISTIO_QUIT_API` | If provided `scuttle` will send a POST to `/quitquitquit` at the given API. Should be in format `http://127.0.0.1:15020`. This is intended for Istio v1.3 and higher. When not given, Istio will be stopped using a `pkill` command. |
| `ISTIO_QUIT_API` | This is the path to envoy's pilot agent interface, in the format `http://127.0.0.1:15020`. If not provided and the `ENVOY_ADMIN_API` is configured with the default port `15000`, the setting is configured automatically. If present (configured or deducted) `scuttle` will send a POST to `/quitquitquit` at the url. |
| `GENERIC_QUIT_ENDPOINTS` | If provided `scuttle` will send a POST to the URL given. Multiple URLs are supported and must be provided as a CSV string. Should be in format `http://myendpoint.com` or `http://myendpoint.com,https://myotherendpoint.com`. The status code response is logged (if logging is enabled) but is not used. A 200 is treated the same as a 404 or 500. `GENERIC_QUIT_ENDPOINTS` is handled before Istio is stopped. |
| `QUIT_WITHOUT_ENVOY_TIMEOUT` | If provided and set to a valid duration, `scuttle` will exit if Envoy does not become available before the end of the timeout and not continue with the passed in executable. If `START_WITHOUT_ENVOY` is also set, this variable will not be taken into account. Also, if `WAIT_FOR_ENVOY_TIMEOUT` is set, this variable will take precedence. |

## How Scuttle stops Istio

Scuttle has two methods to stop Istio. You should configure Scuttle appropriately based on the version of Istio you are using.

| Istio Version | Method |
|---------------|--------|
| 1.3 and higher| `/quitquitquit` endpoint |
| 1.2 and lower | `pkill` command |

### Istio 1.3 and higher

Version 1.3 of Istio introduced an endpoint `/quitquitquit` similar to Envoy. By default this endpoint is available at `http://127.0.0.1:15020` which is the Pilot Agent service, responsible for managing envoy. ([Source](https://github.com/istio/istio/issues/15041))

To enable this, set the environment variable `ISTIO_QUIT_API` to `http://127.0.0.1:15020`.

### Istio 1.2 and lower

Versions 1.2 and lower of Istio have no supported method to stop Istio Sidecars. As a workaround Scuttle stops Istio using the command `pkill -SIGINT pilot-agent`.

To enable this, you must add `shareProcessNamespace: true` to your **Pod** definition in Kubernetes. This allows Scuttle to stop the service running on the sidecar container.

*Note:* This method is used by default if `ISTIO_QUIT_API` is not set

## Example usage in your Job's `Dockerfile`

```dockerfile
Expand Down
30 changes: 2 additions & 28 deletions main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -126,11 +126,6 @@ func kill(exitCode int) {
case config.NeverKillIstioOnFailure && exitCode != 0:
log(fmt.Sprintf(logLineUnformatted, "Skipping Istio kill", "NEVER_KILL_ISTIO_ON_FAILURE is true", exitCode))
os.Exit(exitCode)
case config.IstioQuitAPI == "":
// No istio API sent, fallback to Pkill method
log(fmt.Sprintf(logLineUnformatted, "Stopping Istio with pkill", "ISTIO_QUIT_API is not set", exitCode))
killGenericEndpoints()
killIstioWithPkill()
default:
// Stop istio using api
log(fmt.Sprintf(logLineUnformatted, "Stopping Istio with API", "ISTIO_QUIT_API is set", exitCode))
Expand All @@ -157,34 +152,13 @@ func killGenericEndpoints() {

func killIstioWithAPI() {
log(fmt.Sprintf("Stopping Istio using Istio API '%s' (intended for Istio >v1.2)", config.IstioQuitAPI))

responseSuccess := false
url := fmt.Sprintf("%s/quitquitquit", config.IstioQuitAPI)
code, err := postKill(context.TODO(), url)
if err != nil {
log(fmt.Sprintf("Sent quitquitquit to Istio, error: %d", err))
} else {
log(fmt.Sprintf("Sent quitquitquit to Istio, status code: %d", code))
responseSuccess = code >= 200 && code < 300
}

if !responseSuccess && config.IstioFallbackPkill {
log(fmt.Sprintf("quitquitquit failed, will attempt pkill method"))
killIstioWithPkill()
}
}

func killIstioWithPkill() {
log("Stopping Istio using pkill command (intended for Istio <v1.3)")

cmd := exec.Command("sh", "-c", "pkill -SIGINT pilot-agent")
_, err := cmd.Output()
if err == nil {
log("Process pilot-agent successfully stopped")
} else {
errorMessage := err.Error()
log("pilot-agent could not be stopped, err: " + errorMessage)
return
}
log(fmt.Sprintf("Sent quitquitquit to Istio, status code: %d", code))
}

func waitForEnvoy() context.Context {
Expand Down
20 changes: 20 additions & 0 deletions scuttle_config.go
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Expand Up @@ -2,11 +2,15 @@ package main

import (
"fmt"
"net/url"
"os"
"strings"
"time"
)

const defaultAdminAPIPort = 15000
const defaultQuitAPIPort = 15020

// ScuttleConfig ... represents Scuttle's configuration based on environment variables or defaults.
type ScuttleConfig struct {
LoggingEnabled bool
Expand Down Expand Up @@ -43,6 +47,10 @@ func getConfig() ScuttleConfig {
QuitWithoutEnvoyTimeout: getDurationFromEnv("QUIT_WITHOUT_ENVOY_TIMEOUT", time.Duration(0), loggingEnabled),
}

if config.IstioQuitAPI == "" {
config.IstioQuitAPI = replacePort(config.EnvoyAdminAPI, defaultAdminAPIPort, defaultQuitAPIPort)
}

return config
}

Expand Down Expand Up @@ -122,3 +130,15 @@ func getDurationFromEnv(name string, defaultVal time.Duration, logEnabled bool)

return defaultVal
}

// replacePort returns a URL with the port replaced when the sourceURL is valid and has the original port set.
// If the original port does not match or the sourceURL is invalid an empty string is returned.
func replacePort(sourceURL string, original, replacement int) string {
u, err := url.Parse(sourceURL)
if err != nil || (u.Port() != fmt.Sprintf("%d", original)) {
return ""
}

u.Host = fmt.Sprintf("%s:%d", u.Hostname(), replacement)
return u.String()
}
51 changes: 51 additions & 0 deletions scuttle_config_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,51 @@
package main

import "testing"

func Test_replacePort(t *testing.T) {
type args struct {
sourceURL string
original int
replacement int
}
tests := []struct {
name string
args args
want string
}{
{
name: "Happy flow",
args: args{
sourceURL: "http://localhost:15000",
original: 15000,
replacement: 15020,
},
want: "http://localhost:15020",
},
{
name: "Invalid URL",
args: args{
sourceURL: "notaurl^^ :15000",
original: 15000,
replacement: 15020,
},
want: "",
},
{
name: "Port not matching",
args: args{
sourceURL: "http://localhost:14000",
original: 15000,
replacement: 15020,
},
want: "",
},
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
if got := replacePort(tt.args.sourceURL, tt.args.original, tt.args.replacement); got != tt.want {
t.Errorf("replacePort() = %v, want %v", got, tt.want)
}
})
}
}

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