Cloud-oriented Life

Cloud Native Technology Improves Lives

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FAQs - cert-manager

Error: listen tcp :10250: bind: address already in use on Alibaba Cloud Serverless Kuberneters (ASK)

Encountered an error Back-off restarting failed container when deploying cert-manager-webhook on Alibaba Cloud Serverless Kuberneters (ASK)

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shell@Alicloud:~$ kubectl logs -f cert-manager-webhook-7d6d4c78bc-lr9zh -n cert-manager
W0603 09:48:28.403062       1 client_config.go:608] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
W0603 09:48:28.404700       1 client_config.go:608] Neither --kubeconfig nor --master was specified.  Using the inClusterConfig.  This might not work.
I0603 09:48:28.404863       1 webhook.go:69] cert-manager/webhook "msg"="using dynamic certificate generating using CA stored in Secret resource"  "secret_name"="cert-manager-webhook-ca" "secret_namespace"="cert-manager"
I0603 09:48:28.405047       1 server.go:148] cert-manager/webhook "msg"="listening for insecure healthz connections"  "address"=":6080"
Error: listen tcp :10250: bind: address already in use
...

E0603 09:48:28.405712       1 main.go:38] cert-manager "msg"="error executing command" "error"="listen tcp :10250: bind: address already in use"

Maybe ASK uses a single working node by default, which make it easy to port conflicts.

We can change 10250 to another port to avoid port conflicts。

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# values.yaml

webhook:

  # The port that the webhook should listen on for requests.
  # In GKE private clusters, by default kubernetes apiservers are allowed to
  # talk to the cluster nodes only on 443 and 10250. so configuring
  # securePort: 10250, will work out of the box without needing to add firewall
  # rules or requiring NET_BIND_SERVICE capabilities to bind port numbers <1000
  # securePort: 10250
  securePort: 10251 # change 10250 to another port.

References

[1] cert-manager/values.yaml at master · jetstack/cert-manager - https://github.com/jetstack/cert-manager/blob/master/deploy/charts/cert-manager/values.yaml

[2] Create an ASK cluster - User Guide for Serverless Kubernetes Clusters| Alibaba Cloud Documentation Center - https://www.alibabacloud.com/help/doc-detail/86377.htm

Posted on Edited on In , Word count in article: 14k Reading time ≈ 13 mins.

GNU Wget

GNU Wget is a free software package for retrieving files using HTTP, HTTPS, FTP and FTPS, the most widely used Internet protocols. It is a non-interactive commandline tool, so it may easily be called from scripts, cron jobs, terminals without X-Windows support, etc.

Read more »

Posted on Edited on In , , Word count in article: 4k Reading time ≈ 4 mins.

Dive

Dive is a tool for exploring a docker image, layer contents, and discovering ways to shrink the size of your Docker/OCI image.

Dive

Basic Features

  • Show Docker image contents broken down by layer

As you select a layer on the left, you are shown the contents of that layer combined with all previous layers on the right. Also, you can fully explore the file tree with the arrow keys.

  • Indicate what’s changed in each layer

Files that have changed, been modified, added, or removed are indicated in the file tree. This can be adjusted to show changes for a specific layer, or aggregated changes up to this layer.

  • Estimate “image efficiency”

The lower left pane shows basic layer info and an experimental metric that will guess how much wasted space your image contains. This might be from duplicating files across layers, moving files across layers, or not fully removing files. Both a percentage “score” and total wasted file space is provided.

  • Quick build/analysis cycles

You can build a Docker image and do an immediate analysis with one command: dive build -t some-tag .

You only need to replace your docker build command with the same dive build command.

  • CI Integration

Analyze an image and get a pass/fail result based on the image efficiency and wasted space. Simply set CI=true in the environment when invoking any valid dive command.

  • Multiple Image Sources and Container Engines Supported

With the --source option, you can select where to fetch the container image from:

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$ dive <your-image> --source <source>

Installation

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# macOS
$ brew install dive

# Ubuntu/Debian
$ wget https://github.com/wagoodman/dive/releases/download/v0.9.2/dive_0.9.2_linux_amd64.deb
$ sudo apt install ./dive_0.9.2_linux_amd64.deb

# RHEL/Centos
$ curl -OL https://github.com/wagoodman/dive/releases/download/v0.9.2/dive_0.9.2_linux_amd64.rpm
$ rpm -i dive_0.9.2_linux_amd64.rpm

# Arch Linux
# Available as dive in the Arch User Repository (AUR).
yay -S dive

See [Installation | wagoodman/dive: A tool for exploring each layer in a docker image - https://github.com/wagoodman/dive#installation](https://github.com/wagoodman/dive#installation) to learn more.

## Usages

To analyze a Docker image simply run dive with an image `tag/id/digest`:

```shell
$ dive <your-image-tag>

or if you want to build your image then jump straight into analyzing it:

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$ dive build -t <some-tag> .

CI Integration

Additionally you can run this in your CI pipeline to ensure you’re keeping wasted space to a minimum (this skips the UI):

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$ CI=true dive <your-image>

UI Configuration

No configuration is necessary, however, you can create a config file and override values:

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# supported options are "docker" and "podman"
container-engine: docker
# continue with analysis even if there are errors parsing the image archive
ignore-errors: false
log:
  enabled: true
  path: ./dive.log
  level: info

# Note: you can specify multiple bindings by separating values with a comma.
# Note: UI hinting is derived from the first binding
keybinding:
  # Global bindings
  quit: ctrl+c
  toggle-view: tab
  filter-files: ctrl+f, ctrl+slash

  # Layer view specific bindings
  compare-all: ctrl+a
  compare-layer: ctrl+l

  # File view specific bindings
  toggle-collapse-dir: space
  toggle-collapse-all-dir: ctrl+space
  toggle-added-files: ctrl+a
  toggle-removed-files: ctrl+r
  toggle-modified-files: ctrl+m
  toggle-unmodified-files: ctrl+u
  toggle-filetree-attributes: ctrl+b
  page-up: pgup
  page-down: pgdn

diff:
  # You can change the default files shown in the filetree (right pane). All diff types are shown by default.
  hide:
    - added
    - removed
    - modified
    - unmodified

filetree:
  # The default directory-collapse state
  collapse-dir: false

  # The percentage of screen width the filetree should take on the screen (must be >0 and <1)
  pane-width: 0.5

  # Show the file attributes next to the filetree
  show-attributes: true

layer:
  # Enable showing all changes from this layer and every previous layer
  show-aggregated-changes: false

dive will search for configs in the following locations:

  • $XDG_CONFIG_HOME/dive/*.yaml

  • $XDG_CONFIG_DIRS/dive/*.yaml

  • ~/.config/dive/*.yaml

  • ~/.dive.yaml

References

[1] wagoodman/dive: A tool for exploring each layer in a docker image - https://github.com/wagoodman/dive

[2] docker history | Docker Documentation - https://docs.docker.com/engine/reference/commandline/history/

[3] Empowering App Development for Developers | Docker - https://www.docker.com/

Posted on Edited on In , , Word count in article: 2k Reading time ≈ 2 mins.

Can’t save in background: fork: Cannot allocate memory

APP log

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# ${RAILS_ROOT}/log/production.log
...
MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.
...

Redis Log - Can’t save in background: fork: Cannot allocate memory

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[root@cloudolife /root]# tail -f /var/log/redis/redis.log
1573:M 14 Jan 16:56:04.011 * 1 changes in 900 seconds. Saving...
1573:M 14 Jan 16:56:04.011 # Can't save in background: fork: Cannot allocate memory
1573:M 14 Feb 16:56:10.045 * 1 changes in 900 seconds. Saving...

In traditional way, Linux gives you three options for what happens when a process tries to allocate some more memory, controlled by the value of the vm.overcommit_memory sysctl:

The kernel gives you the memory unless it thinks you would clearly overcommit the system (mode 0, the default, ‘heuristic overcommit’).

the kernel always gives you the memory (mode 1, ‘always overcommit’).

the kernel refuses to give you more memory if it would take the committed address space over the commit limit (mode 2, what I call ‘strict overcommit’).
(Disclaimer: all of this assumes a relatively recent 2.6 kernel.)

These settings control how Linux handles virtual memory limits.

After changing this setting from 0 to 1 Redis started persisting the data immediately and the overall performance increased dramatically.

To do so either open the file /proc/sys/vm/overcommit_memory and remove 0 and put 1 or run the following command.

This might now work as the file may be already in use by the system.

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$ echo 1 > /proc/sys/vm/overcommit_memory

So other way to do the same is to add vm.overcommit_memory = 1 to /etc/sysctl.conf and then reboot or run the command sysctl vm.overcommit_memory=1 for this to take effect.

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$ vi /etc/sysctl.conf
# /etc/sysctl.conf
vm.overcommit_memory=1

$ sysctl -p

See Can’t save in background: fork: Cannot allocate memory Redis ~ Appychip - https://jee-appy.blogspot.com/2016/04/can-not-save-in-background-fork-redis.html to learn more.

References

[1] Redis - https://redis.io/

[2] Can’t save in background: fork: Cannot allocate memory Redis ~ Appychip - https://jee-appy.blogspot.com/2016/04/can-not-save-in-background-fork-redis.html

Posted on Edited on In , , Word count in article: 4.7k Reading time ≈ 4 mins.

Angular Sentry

Sentry’s SDKs enable automatic reporting of errors and exceptions.

On this page, we get you up and running with Sentry’s SDK, so that it will automatically report errors and exceptions in your Angular application.

Prerequisites

You should have an sentry.io account or a Self-Hosted Sentry sever.

Install

Sentry captures data by using an SDK within your application’s runtime.

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$ npm install --save @sentry/angular @sentry/tracing

Configure

Configuration should happen as early as possible in your Angular application’s lifecycle.

Once this is done, Sentry’s Angular SDK captures all unhandled exceptions and transactions.

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import { enableProdMode } from "@angular/core";
import { platformBrowserDynamic } from "@angular/platform-browser-dynamic";
import * as Sentry from "@sentry/angular";
import { Integrations } from "@sentry/tracing";
import { AppModule } from "./app/app.module";

Sentry.init({
  dsn: "https://[email protected]/0" ,
  integrations: [
    // Registers and configures the Tracing integration,
    // which automatically instruments your application to monitor its
    // performance, including custom Angular routing instrumentation
    new Integrations.BrowserTracing({
      tracingOrigins: ["localhost", "https://yourserver.io/api"],
      routingInstrumentation: Sentry.routingInstrumentation,
    }),
  ],

  // Set tracesSampleRate to 1.0 to capture 100%
  // of transactions for performance monitoring.
  // We recommend adjusting this value in production
  tracesSampleRate: 1.0,
});


platformBrowserDynamic()
  .bootstrapModule(AppModule)
  .then(success => console.log(`Bootstrap success`))
  .catch(err => console.error(err));

You can also configure @sentry/angular to catch any Angular-specific exceptions reported through the @angular/core/ErrorHandler provider.

@sentry/angular exports a Trace Service, Directive, and Decorators that leverages the @sentry/tracing, Sentry’s Tracing integration, to add Angular-related spans to transactions. The service itself tracks route changes and durations, where directive and decorators are tracking component initializations.

Automatically Send Errors with ErrorHandler

@sentry/angular exports a function to instantiate an ErrorHandler provider that will automatically send JavaScript errors captured by the Angular’s error handler.

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import { NgModule, ErrorHandler } from "@angular/core";
import * as Sentry from "@sentry/angular";

@NgModule({
  // ...
  providers: [
    {
      provide: ErrorHandler,
      useValue: Sentry.createErrorHandler({
        showDialog: true,
      }),
    },
  ],
  // ...
})

export class AppModule {}

You can configure the behavior of createErrorHandler. For more details see the ErrorHandlerOptions interface in our repository.

Register TraceService

In Angular’s DI system, register TraceService as a provider with a Router as its dependency:

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import { NgModule } from "@angular/core";
import { Router } from "@angular/router";
import * as Sentry from "@sentry/angular";

@NgModule({
  // ...
  providers: [
    {
      provide: Sentry.TraceService,
      deps: [Router],
    },
  ],
  // ...
})

export class AppModule {}

Then, either require the TraceService from inside AppModule or use APP_INITIALIZER to force instantiate Tracing.

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@NgModule({
  // ...
})
export class AppModule {
  constructor(trace: Sentry.TraceService) {}
}

or

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import { APP_INITIALIZER } from "@angular/core";
@NgModule({
  // ...
  providers: [
    {
      provide: APP_INITIALIZER,
      useFactory: () => () => {},
      deps: [Sentry.TraceService],
      multi: true,
    },
  ],
  // ...
})

export class AppModule {}

Verify

This snippet includes an intentional error, so you can test that everything is working as soon as you set it up:

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myUndefinedFunction();

Errors triggered from within Browser DevTools are sandboxed, so will not trigger an error handler. Place the snippet directly in your code instead.

Learn more about manually capturing an error or message in our Usage documentation.

To view and resolve the recorded error, log into sentry.io or your and open your project. Clicking on the error’s title will open a page where you can see detailed information and mark it as resolved.

References

[1] Angular | Sentry Documentation - https://docs.sentry.io/platforms/javascript/guides/angular/

[2] Sentry Documentation | Sentry Documentation - https://docs.sentry.io/

[4] Sentry | Error Tracking Software — JavaScript, Python, PHP, Ruby, more - https://sentry.io/welcome/

[5] Angular - https://angular.io/

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