Liam Hurst

Liam Hurst

1559105121

Build Docker Images and Host a Docker Image Repository with GitLab

In this tutorial, you’ll learn how to build Docker images and host a Docker image repository with GitLab. We set up a new GitLab runner to build Docker images, created a private Docker registry to store them in, and updated a Node.js app to be built and tested inside of Docker containers.

Introduction

Containerization is quickly becoming the most accepted method of packaging and deploying applications in cloud environments. The standardization it provides, along with its resource efficiency (when compared to full virtual machines) and flexibility, make it a great enabler of the modern DevOps mindset. Many interesting cloud native deployment, orchestration, and monitoring strategies become possible when your applications and microservices are fully containerized.

Docker containers are by far the most common container type today. Though public Docker image repositories like Docker Hub are full of containerized open source software images that you can docker pull and use today, for private code you’ll need to either pay a service to build and store your images, or run your own software to do so.

GitLab Community Edition is a self-hosted software suite that provides Git repository hosting, project tracking, CI/CD services, and a Docker image registry, among other features. In this tutorial we will use GitLab’s continuous integration service to build Docker images from an example Node.js app. These images will then be tested and uploaded to our own private Docker registry.

Prerequisites

Before we begin, we need to set up a secure GitLab server, and a GitLab CI runner to execute continuous integration tasks. The sections below will provide links and more details.

A GitLab Server Secured with SSL

To store our source code, run CI/CD tasks, and host the Docker registry, we need a GitLab instance installed on an Ubuntu 16.04 server. GitLab currently recommends a server with at least 2 CPU cores and 4GB of RAM. Additionally, we’ll secure the server with SSL certificates from Let’s Encrypt. To do so, you’ll need a domain name pointed at the server.

A GitLab CI Runner

Set Up Continuous Integration Pipelines with GitLab CI on Ubuntu 16.04 will give you an overview of GitLab’s CI service, and show you how to set up a CI runner to process jobs. We will build on top of the demo app and runner infrastructure created in this tutorial.

Step 1 — Setting Up a Privileged GitLab CI Runner

In the prerequisite GitLab continuous integration tutorial, we set up a GitLab runner using sudo gitlab-runner register and its interactive configuration process. This runner is capable of running builds and tests of software inside of isolated Docker containers.

However, in order to build Docker images, our runner needs full access to a Docker service itself. The recommended way to configure this is to use Docker’s official docker-in-docker image to run the jobs. This requires granting the runner a special privileged execution mode, so we’ll create a second runner with this mode enabled.

Note: Granting the runner privileged mode basically disables all of the security advantages of using containers. Unfortunately, the other methods of enabling Docker-capable runners also carry similar security implications. Please look at the official GitLab documentation on Docker Build to learn more about the different runner options and which is best for your situation.

Read Also: How to Create Docker Image with MySQL Database

Because there are security implications to using a privileged runner, we are going to create a project-specific runner that will only accept Docker jobs on our hello_hapi project (GitLab admins can always manually add this runner to other projects at a later time). From your hello_hapi project page, click Settings at the bottom of the left-hand menu, then click CI/CD in the submenu:

Build Docker Images and Host a Docker Image Repository with GitLab

Now click the Expand button next to the Runners settings section:

Build Docker Images and Host a Docker Image Repository with GitLab

There will be some information about setting up a Specific Runner, including a registration token. Take note of this token. When we use it to register a new runner, the runner will be locked to this project only.

Build Docker Images and Host a Docker Image Repository with GitLab

While we’re on this page, click the Disable shared Runners button. We want to make sure our Docker jobs always run on our privileged runner. If a non-privileged shared runner was available, GitLab might choose to use that one, which would result in build errors.

Log in to the server that has your current CI runner on it. If you don’t have a machine set up with runners already, go back and complete the Installing the GitLab CI Runner Service

section of the prerequisite tutorial before proceeding.

Now, run the following command to set up the privileged project-specific runner:

    sudo gitlab-runner register -n \
      --url https://gitlab.example.com/ \
      --registration-token your-token \
      --executor docker \
      --description "docker-builder" \
      --docker-image "docker:latest" \
      --docker-privileged

Output

Registering runner... succeeded                     runner=61SR6BwV
Runner registered successfully. Feel free to start it, but if it's running already the config should be automatically reloaded!

Be sure to substitute your own information. We set all of our runner options on the command line instead of using the interactive prompts, because the prompts don’t allow us to specify --docker-privileged mode.

Your runner is now set up, registered, and running. To verify, switch back to your browser. Click the wrench icon in the main GitLab menu bar, then click Runners in the left-hand menu. Your runners will be listed:

Build Docker Images and Host a Docker Image Repository with GitLab

Now that we have a runner capable of building Docker images, let’s set up a private Docker registry for it to push images to.

Read Also: Docker All The Things

Step 2 — Setting Up GitLab’s Docker Registry

Setting up your own Docker registry lets you push and pull images from your own private server, increasing security and reducing the dependencies your workflow has on outside services.

GitLab will set up a private Docker registry with just a few configuration updates. First we’ll set up the URL where the registry will reside. Then we will (optionally) configure the registry to use an S3-compatible object storage service to store its data.

SSH into your GitLab server, then open up the GitLab configuration file:

sudo nano /etc/gitlab/gitlab.rb

Scroll down to the Container Registry settings section. We’re going to uncomment the registry_external_url line and set it to our GitLab hostname with a port number of 5555:

/etc/gitlab/gitlab.rb

registry_external_url 'https://gitlab.example.com:5555'

Next, add the following two lines to tell the registry where to find our Let’s Encrypt certificates:

/etc/gitlab/gitlab.rb

registry_nginx['ssl_certificate'] = "/etc/letsencrypt/live/gitlab.example.com/fullchain.pem"
registry_nginx['ssl_certificate_key'] = "/etc/letsencrypt/live/gitlab.example.com/privkey.pem"

Save and close the file, then reconfigure GitLab:

sudo gitlab-ctl reconfigure

Output

gitlab Reconfigured!

Update the firewall to allow traffic to the registry port:

sudo ufw allow 5555

Now switch to another machine with Docker installed, and log in to the private Docker registry. If you don’t have Docker on your local development computer, you can use whichever server is set up to run your GitLab CI jobs, as it has Docker installed already:

docker login gitlab.example.com:5555

You will be prompted for your username and password. Use your GitLab credentials to log in.

Output
Login Succeeded 

Success! The registry is set up and working. Currently it will store files on the GitLab server’s local filesystem. If you’d like to use an object storage service instead, continue with this section. If not, skip down to Step 3.

To set up an object storage backend for the registry, we need to know the following information about our object storage service:

  • Access Key
  • Secret Key
  • Region (us-east-1) for example, if using Amazon S3, or Region Endpoint if using an S3-compatible service ([https://nyc.digitaloceanspaces.com](https://nyc.digitaloceanspaces.com))
  • Bucket Name

If you’re using DigitalOcean Spaces, you can find out how to set up a new Space and get the above information by reading How To Create a DigitalOcean Space and API Key.

When you have your object storage information, open the GitLab configuration file:

sudo nano /etc/gitlab/gitlab.rb

Once again, scroll down to the container registry section. Look for the registry['storage'] block, uncomment it, and update it to the following, again making sure to substitute your own information where appropriate:

/etc/gitlab/gitlab.rb

registry['storage'] = {
  's3' => {
    'accesskey' => 'your-key',
    'secretkey' => 'your-secret',
    'bucket' => 'your-bucket-name',
    'region' => 'nyc3',
    'regionendpoint' => 'https://nyc3.digitaloceanspaces.com'
  }
}

If you’re using Amazon S3, you only need region and not regionendpoint. If you’re using an S3-compatible service like Spaces, you’ll need regionendpoint. In this case region doesn’t actually configure anything and the value you enter doesn’t matter, but it still needs to be present and not blank.

Save and close the file.

Note: There is currently a bug where the registry will shut down after thirty seconds if your object storage bucket is empty. To avoid this, put a file in your bucket before running the next step. You can remove it later, after the registry has added its own objects.

If you are using DigitalOcean Spaces, you can drag and drop to upload a file using the Control Panel interface.

Reconfigure GitLab one more time:

sudo gitlab-ctl reconfigure

On your other Docker machine, log in to the registry again to make sure all is well:

docker login gitlab.example.com:5555

You should get a Login Succeeded message.

Now that we’ve got our Docker registry set up, let’s update our application’s CI configuration to build and test our app, and push Docker images to our private registry.

Step 3 — Updating gitlab-ci.yaml and Building a Docker Image

Note: If you didn’t complete the prerequisite article on GitLab CI you’ll need to copy over the example repository to your GitLab server. Follow the Copying the Example Repository From GitHub section to do so.

To get our app building in Docker, we need to update the .gitlab-ci.yml file. You can edit this file right in GitLab by clicking on it from the main project page, then clicking the Edit button. Alternately, you could clone the repo to your local machine, edit the file, then git push it back to GitLab. That would look like this:

    git clone git@gitlab.example.com:sammy/hello_hapi.git
    cd hello_hapi
    # edit the file w/ your favorite editor
    git commit -am "updating ci configuration"
    git push

First, delete everything in the file, then paste in the following configuration:

.gitlab-ci.yml

image: docker:latest
services:
- docker:dind

stages:
- build
- test
- release

variables:
  TEST_IMAGE: gitlab.example.com:5555/sammy/hello_hapi:$CI_COMMIT_REF_NAME
  RELEASE_IMAGE: gitlab.example.com:5555/sammy/hello_hapi:latest

before_script:
  - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN gitlab.example.com:5555

build:
  stage: build
  script:
    - docker build --pull -t $TEST_IMAGE .
    - docker push $TEST_IMAGE

test:
  stage: test
  script:
    - docker pull $TEST_IMAGE
    - docker run $TEST_IMAGE npm test

release:
  stage: release
  script:
    - docker pull $TEST_IMAGE
    - docker tag $TEST_IMAGE $RELEASE_IMAGE
    - docker push $RELEASE_IMAGE
  only:
    - master

Be sure to update the highlighted URLs and usernames with your own information, then save with the Commit changes button in GitLab. If you’re updating the file outside of GitLab, commit the changes and git push back to GitLab.

This new config file tells GitLab to use the latest docker image (image: docker:latest) and link it to the docker-in-docker service (docker:dind). It then defines build, test, and release stages. The build stage builds the Docker image using the Dockerfile provided in the repo, then uploads it to our Docker image registry. If that succeeds, the test stage will download the image we just built and run the npm test command inside it. If the test stage is successful, the release stage will pull the image, tag it as hello_hapi:latest and push it back to the registry.

Depending on your workflow, you could also add additional test stages, or even deploy stages that push the app to a staging or production environment.

Updating the configuration file should have triggered a new build. Return to the hello_hapi project in GitLab and click on the CI status indicator for the commit:

Build Docker Images and Host a Docker Image Repository with GitLab

On the resulting page you can then click on any of the stages to see their progress:

Build Docker Images and Host a Docker Image Repository with GitLab

Build Docker Images and Host a Docker Image Repository with GitLab

Eventually, all stages should indicate they were successful by showing green check mark icons. We can find the Docker images that were just built by clicking the Registry item in the left-hand menu:

Build Docker Images and Host a Docker Image Repository with GitLab

If you click the little “document” icon next to the image name, it will copy the appropriate docker pull ... command to your clipboard. You can then pull and run your image:

    docker pull gitlab.example.com:5555/sammy/hello_hapi:latest
    docker run -it --rm -p 3000:3000 gitlab.example.com:5555/sammy/hello_hapi:latest

Output

> hello@1.0.0 start /usr/src/app
> node app.js

Server running at: http://56fd5df5ddd3:3000

The image has been pulled down from the registry and started in a container. Switch to your browser and connect to the app on port 3000 to test. In this case we’re running the container on our local machine, so we can access it via localhost at the following URL:

http://localhost:3000/hello/test

Output

Hello, test!

Success! You can stop the container with CTRL-C. From now on, every time we push new code to the master branch of our repository, we’ll automatically build and test a new hello_hapi:latest image.

Conclusion

In this tutorial we set up a new GitLab runner to build Docker images, created a private Docker registry to store them in, and updated a Node.js app to be built and tested inside of Docker containers.

#docker #git #ubuntu

What is GEEK

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Build Docker Images and Host a Docker Image Repository with GitLab
Queenie  Davis

Queenie Davis

1653123600

EasyMDE: Simple, Beautiful and Embeddable JavaScript Markdown Editor

EasyMDE - Markdown Editor 

This repository is a fork of SimpleMDE, made by Sparksuite. Go to the dedicated section for more information.

A drop-in JavaScript text area replacement for writing beautiful and understandable Markdown. EasyMDE allows users who may be less experienced with Markdown to use familiar toolbar buttons and shortcuts.

In addition, the syntax is rendered while editing to clearly show the expected result. Headings are larger, emphasized words are italicized, links are underlined, etc.

EasyMDE also features both built-in auto saving and spell checking. The editor is entirely customizable, from theming to toolbar buttons and javascript hooks.

Try the demo

Preview

Quick access

Install EasyMDE

Via npm:

npm install easymde

Via the UNPKG CDN:

<link rel="stylesheet" href="https://unpkg.com/easymde/dist/easymde.min.css">
<script src="https://unpkg.com/easymde/dist/easymde.min.js"></script>

Or jsDelivr:

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/easymde/dist/easymde.min.css">
<script src="https://cdn.jsdelivr.net/npm/easymde/dist/easymde.min.js"></script>

How to use

Loading the editor

After installing and/or importing the module, you can load EasyMDE onto the first textarea element on the web page:

<textarea></textarea>
<script>
const easyMDE = new EasyMDE();
</script>

Alternatively you can select a specific textarea, via JavaScript:

<textarea id="my-text-area"></textarea>
<script>
const easyMDE = new EasyMDE({element: document.getElementById('my-text-area')});
</script>

Editor functions

Use easyMDE.value() to get the content of the editor:

<script>
easyMDE.value();
</script>

Use easyMDE.value(val) to set the content of the editor:

<script>
easyMDE.value('New input for **EasyMDE**');
</script>

Configuration

Options list

  • autoDownloadFontAwesome: If set to true, force downloads Font Awesome (used for icons). If set to false, prevents downloading. Defaults to undefined, which will intelligently check whether Font Awesome has already been included, then download accordingly.
  • autofocus: If set to true, focuses the editor automatically. Defaults to false.
  • autosave: Saves the text that's being written and will load it back in the future. It will forget the text when the form it's contained in is submitted.
    • enabled: If set to true, saves the text automatically. Defaults to false.
    • delay: Delay between saves, in milliseconds. Defaults to 10000 (10 seconds).
    • submit_delay: Delay before assuming that submit of the form failed and saving the text, in milliseconds. Defaults to autosave.delay or 10000 (10 seconds).
    • uniqueId: You must set a unique string identifier so that EasyMDE can autosave. Something that separates this from other instances of EasyMDE elsewhere on your website.
    • timeFormat: Set DateTimeFormat. More information see DateTimeFormat instances. Default locale: en-US, format: hour:minute.
    • text: Set text for autosave.
  • autoRefresh: Useful, when initializing the editor in a hidden DOM node. If set to { delay: 300 }, it will check every 300 ms if the editor is visible and if positive, call CodeMirror's refresh().
  • blockStyles: Customize how certain buttons that style blocks of text behave.
    • bold: Can be set to ** or __. Defaults to **.
    • code: Can be set to ``` or ~~~. Defaults to ```.
    • italic: Can be set to * or _. Defaults to *.
  • unorderedListStyle: can be *, - or +. Defaults to *.
  • scrollbarStyle: Chooses a scrollbar implementation. The default is "native", showing native scrollbars. The core library also provides the "null" style, which completely hides the scrollbars. Addons can implement additional scrollbar models.
  • element: The DOM element for the textarea element to use. Defaults to the first textarea element on the page.
  • forceSync: If set to true, force text changes made in EasyMDE to be immediately stored in original text area. Defaults to false.
  • hideIcons: An array of icon names to hide. Can be used to hide specific icons shown by default without completely customizing the toolbar.
  • indentWithTabs: If set to false, indent using spaces instead of tabs. Defaults to true.
  • initialValue: If set, will customize the initial value of the editor.
  • previewImagesInEditor: - EasyMDE will show preview of images, false by default, preview for images will appear only for images on separate lines.
  • imagesPreviewHandler: - A custom function for handling the preview of images. Takes the parsed string between the parantheses of the image markdown ![]( ) as argument and returns a string that serves as the src attribute of the <img> tag in the preview. Enables dynamic previewing of images in the frontend without having to upload them to a server, allows copy-pasting of images to the editor with preview.
  • insertTexts: Customize how certain buttons that insert text behave. Takes an array with two elements. The first element will be the text inserted before the cursor or highlight, and the second element will be inserted after. For example, this is the default link value: ["[", "](http://)"].
    • horizontalRule
    • image
    • link
    • table
  • lineNumbers: If set to true, enables line numbers in the editor.
  • lineWrapping: If set to false, disable line wrapping. Defaults to true.
  • minHeight: Sets the minimum height for the composition area, before it starts auto-growing. Should be a string containing a valid CSS value like "500px". Defaults to "300px".
  • maxHeight: Sets fixed height for the composition area. minHeight option will be ignored. Should be a string containing a valid CSS value like "500px". Defaults to undefined.
  • onToggleFullScreen: A function that gets called when the editor's full screen mode is toggled. The function will be passed a boolean as parameter, true when the editor is currently going into full screen mode, or false.
  • parsingConfig: Adjust settings for parsing the Markdown during editing (not previewing).
    • allowAtxHeaderWithoutSpace: If set to true, will render headers without a space after the #. Defaults to false.
    • strikethrough: If set to false, will not process GFM strikethrough syntax. Defaults to true.
    • underscoresBreakWords: If set to true, let underscores be a delimiter for separating words. Defaults to false.
  • overlayMode: Pass a custom codemirror overlay mode to parse and style the Markdown during editing.
    • mode: A codemirror mode object.
    • combine: If set to false, will replace CSS classes returned by the default Markdown mode. Otherwise the classes returned by the custom mode will be combined with the classes returned by the default mode. Defaults to true.
  • placeholder: If set, displays a custom placeholder message.
  • previewClass: A string or array of strings that will be applied to the preview screen when activated. Defaults to "editor-preview".
  • previewRender: Custom function for parsing the plaintext Markdown and returning HTML. Used when user previews.
  • promptURLs: If set to true, a JS alert window appears asking for the link or image URL. Defaults to false.
  • promptTexts: Customize the text used to prompt for URLs.
    • image: The text to use when prompting for an image's URL. Defaults to URL of the image:.
    • link: The text to use when prompting for a link's URL. Defaults to URL for the link:.
  • uploadImage: If set to true, enables the image upload functionality, which can be triggered by drag and drop, copy-paste and through the browse-file window (opened when the user click on the upload-image icon). Defaults to false.
  • imageMaxSize: Maximum image size in bytes, checked before upload (note: never trust client, always check the image size at server-side). Defaults to 1024 * 1024 * 2 (2 MB).
  • imageAccept: A comma-separated list of mime-types used to check image type before upload (note: never trust client, always check file types at server-side). Defaults to image/png, image/jpeg.
  • imageUploadFunction: A custom function for handling the image upload. Using this function will render the options imageMaxSize, imageAccept, imageUploadEndpoint and imageCSRFToken ineffective.
    • The function gets a file and onSuccess and onError callback functions as parameters. onSuccess(imageUrl: string) and onError(errorMessage: string)
  • imageUploadEndpoint: The endpoint where the images data will be sent, via an asynchronous POST request. The server is supposed to save this image, and return a JSON response.
    • if the request was successfully processed (HTTP 200 OK): {"data": {"filePath": "<filePath>"}} where filePath is the path of the image (absolute if imagePathAbsolute is set to true, relative if otherwise);
    • otherwise: {"error": "<errorCode>"}, where errorCode can be noFileGiven (HTTP 400 Bad Request), typeNotAllowed (HTTP 415 Unsupported Media Type), fileTooLarge (HTTP 413 Payload Too Large) or importError (see errorMessages below). If errorCode is not one of the errorMessages, it is alerted unchanged to the user. This allows for server-side error messages. No default value.
  • imagePathAbsolute: If set to true, will treat imageUrl from imageUploadFunction and filePath returned from imageUploadEndpoint as an absolute rather than relative path, i.e. not prepend window.location.origin to it.
  • imageCSRFToken: CSRF token to include with AJAX call to upload image. For various instances like Django, Spring and Laravel.
  • imageCSRFName: CSRF token filed name to include with AJAX call to upload image, applied when imageCSRFToken has value, defaults to csrfmiddlewaretoken.
  • imageCSRFHeader: If set to true, passing CSRF token via header. Defaults to false, which pass CSRF through request body.
  • imageTexts: Texts displayed to the user (mainly on the status bar) for the import image feature, where #image_name#, #image_size# and #image_max_size# will replaced by their respective values, that can be used for customization or internationalization:
    • sbInit: Status message displayed initially if uploadImage is set to true. Defaults to Attach files by drag and dropping or pasting from clipboard..
    • sbOnDragEnter: Status message displayed when the user drags a file to the text area. Defaults to Drop image to upload it..
    • sbOnDrop: Status message displayed when the user drops a file in the text area. Defaults to Uploading images #images_names#.
    • sbProgress: Status message displayed to show uploading progress. Defaults to Uploading #file_name#: #progress#%.
    • sbOnUploaded: Status message displayed when the image has been uploaded. Defaults to Uploaded #image_name#.
    • sizeUnits: A comma-separated list of units used to display messages with human-readable file sizes. Defaults to B, KB, MB (example: 218 KB). You can use B,KB,MB instead if you prefer without whitespaces (218KB).
  • errorMessages: Errors displayed to the user, using the errorCallback option, where #image_name#, #image_size# and #image_max_size# will replaced by their respective values, that can be used for customization or internationalization:
    • noFileGiven: The server did not receive any file from the user. Defaults to You must select a file..
    • typeNotAllowed: The user send a file type which doesn't match the imageAccept list, or the server returned this error code. Defaults to This image type is not allowed..
    • fileTooLarge: The size of the image being imported is bigger than the imageMaxSize, or if the server returned this error code. Defaults to Image #image_name# is too big (#image_size#).\nMaximum file size is #image_max_size#..
    • importError: An unexpected error occurred when uploading the image. Defaults to Something went wrong when uploading the image #image_name#..
  • errorCallback: A callback function used to define how to display an error message. Defaults to (errorMessage) => alert(errorMessage).
  • renderingConfig: Adjust settings for parsing the Markdown during previewing (not editing).
    • codeSyntaxHighlighting: If set to true, will highlight using highlight.js. Defaults to false. To use this feature you must include highlight.js on your page or pass in using the hljs option. For example, include the script and the CSS files like:
      <script src="https://cdn.jsdelivr.net/highlight.js/latest/highlight.min.js"></script>
      <link rel="stylesheet" href="https://cdn.jsdelivr.net/highlight.js/latest/styles/github.min.css">
    • hljs: An injectible instance of highlight.js. If you don't want to rely on the global namespace (window.hljs), you can provide an instance here. Defaults to undefined.
    • markedOptions: Set the internal Markdown renderer's options. Other renderingConfig options will take precedence.
    • singleLineBreaks: If set to false, disable parsing GitHub Flavored Markdown (GFM) single line breaks. Defaults to true.
    • sanitizerFunction: Custom function for sanitizing the HTML output of Markdown renderer.
  • shortcuts: Keyboard shortcuts associated with this instance. Defaults to the array of shortcuts.
  • showIcons: An array of icon names to show. Can be used to show specific icons hidden by default without completely customizing the toolbar.
  • spellChecker: If set to false, disable the spell checker. Defaults to true. Optionally pass a CodeMirrorSpellChecker-compliant function.
  • inputStyle: textarea or contenteditable. Defaults to textarea for desktop and contenteditable for mobile. contenteditable option is necessary to enable nativeSpellcheck.
  • nativeSpellcheck: If set to false, disable native spell checker. Defaults to true.
  • sideBySideFullscreen: If set to false, allows side-by-side editing without going into fullscreen. Defaults to true.
  • status: If set to false, hide the status bar. Defaults to the array of built-in status bar items.
    • Optionally, you can set an array of status bar items to include, and in what order. You can even define your own custom status bar items.
  • styleSelectedText: If set to false, remove the CodeMirror-selectedtext class from selected lines. Defaults to true.
  • syncSideBySidePreviewScroll: If set to false, disable syncing scroll in side by side mode. Defaults to true.
  • tabSize: If set, customize the tab size. Defaults to 2.
  • theme: Override the theme. Defaults to easymde.
  • toolbar: If set to false, hide the toolbar. Defaults to the array of icons.
  • toolbarTips: If set to false, disable toolbar button tips. Defaults to true.
  • direction: rtl or ltr. Changes text direction to support right-to-left languages. Defaults to ltr.

Options example

Most options demonstrate the non-default behavior:

const editor = new EasyMDE({
    autofocus: true,
    autosave: {
        enabled: true,
        uniqueId: "MyUniqueID",
        delay: 1000,
        submit_delay: 5000,
        timeFormat: {
            locale: 'en-US',
            format: {
                year: 'numeric',
                month: 'long',
                day: '2-digit',
                hour: '2-digit',
                minute: '2-digit',
            },
        },
        text: "Autosaved: "
    },
    blockStyles: {
        bold: "__",
        italic: "_",
    },
    unorderedListStyle: "-",
    element: document.getElementById("MyID"),
    forceSync: true,
    hideIcons: ["guide", "heading"],
    indentWithTabs: false,
    initialValue: "Hello world!",
    insertTexts: {
        horizontalRule: ["", "\n\n-----\n\n"],
        image: ["![](http://", ")"],
        link: ["[", "](https://)"],
        table: ["", "\n\n| Column 1 | Column 2 | Column 3 |\n| -------- | -------- | -------- |\n| Text     | Text      | Text     |\n\n"],
    },
    lineWrapping: false,
    minHeight: "500px",
    parsingConfig: {
        allowAtxHeaderWithoutSpace: true,
        strikethrough: false,
        underscoresBreakWords: true,
    },
    placeholder: "Type here...",

    previewClass: "my-custom-styling",
    previewClass: ["my-custom-styling", "more-custom-styling"],

    previewRender: (plainText) => customMarkdownParser(plainText), // Returns HTML from a custom parser
    previewRender: (plainText, preview) => { // Async method
        setTimeout(() => {
            preview.innerHTML = customMarkdownParser(plainText);
        }, 250);

        return "Loading...";
    },
    promptURLs: true,
    promptTexts: {
        image: "Custom prompt for URL:",
        link: "Custom prompt for URL:",
    },
    renderingConfig: {
        singleLineBreaks: false,
        codeSyntaxHighlighting: true,
        sanitizerFunction: (renderedHTML) => {
            // Using DOMPurify and only allowing <b> tags
            return DOMPurify.sanitize(renderedHTML, {ALLOWED_TAGS: ['b']})
        },
    },
    shortcuts: {
        drawTable: "Cmd-Alt-T"
    },
    showIcons: ["code", "table"],
    spellChecker: false,
    status: false,
    status: ["autosave", "lines", "words", "cursor"], // Optional usage
    status: ["autosave", "lines", "words", "cursor", {
        className: "keystrokes",
        defaultValue: (el) => {
            el.setAttribute('data-keystrokes', 0);
        },
        onUpdate: (el) => {
            const keystrokes = Number(el.getAttribute('data-keystrokes')) + 1;
            el.innerHTML = `${keystrokes} Keystrokes`;
            el.setAttribute('data-keystrokes', keystrokes);
        },
    }], // Another optional usage, with a custom status bar item that counts keystrokes
    styleSelectedText: false,
    sideBySideFullscreen: false,
    syncSideBySidePreviewScroll: false,
    tabSize: 4,
    toolbar: false,
    toolbarTips: false,
});

Toolbar icons

Below are the built-in toolbar icons (only some of which are enabled by default), which can be reorganized however you like. "Name" is the name of the icon, referenced in the JavaScript. "Action" is either a function or a URL to open. "Class" is the class given to the icon. "Tooltip" is the small tooltip that appears via the title="" attribute. Note that shortcut hints are added automatically and reflect the specified action if it has a key bind assigned to it (i.e. with the value of action set to bold and that of tooltip set to Bold, the final text the user will see would be "Bold (Ctrl-B)").

Additionally, you can add a separator between any icons by adding "|" to the toolbar array.

NameActionTooltip
Class
boldtoggleBoldBold
fa fa-bold
italictoggleItalicItalic
fa fa-italic
strikethroughtoggleStrikethroughStrikethrough
fa fa-strikethrough
headingtoggleHeadingSmallerHeading
fa fa-header
heading-smallertoggleHeadingSmallerSmaller Heading
fa fa-header
heading-biggertoggleHeadingBiggerBigger Heading
fa fa-lg fa-header
heading-1toggleHeading1Big Heading
fa fa-header header-1
heading-2toggleHeading2Medium Heading
fa fa-header header-2
heading-3toggleHeading3Small Heading
fa fa-header header-3
codetoggleCodeBlockCode
fa fa-code
quotetoggleBlockquoteQuote
fa fa-quote-left
unordered-listtoggleUnorderedListGeneric List
fa fa-list-ul
ordered-listtoggleOrderedListNumbered List
fa fa-list-ol
clean-blockcleanBlockClean block
fa fa-eraser
linkdrawLinkCreate Link
fa fa-link
imagedrawImageInsert Image
fa fa-picture-o
tabledrawTableInsert Table
fa fa-table
horizontal-ruledrawHorizontalRuleInsert Horizontal Line
fa fa-minus
previewtogglePreviewToggle Preview
fa fa-eye no-disable
side-by-sidetoggleSideBySideToggle Side by Side
fa fa-columns no-disable no-mobile
fullscreentoggleFullScreenToggle Fullscreen
fa fa-arrows-alt no-disable no-mobile
guideThis linkMarkdown Guide
fa fa-question-circle
undoundoUndo
fa fa-undo
redoredoRedo
fa fa-redo

Toolbar customization

Customize the toolbar using the toolbar option.

Only the order of existing buttons:

const easyMDE = new EasyMDE({
    toolbar: ["bold", "italic", "heading", "|", "quote"]
});

All information and/or add your own icons

const easyMDE = new EasyMDE({
    toolbar: [
        {
            name: "bold",
            action: EasyMDE.toggleBold,
            className: "fa fa-bold",
            title: "Bold",
        },
        "italics", // shortcut to pre-made button
        {
            name: "custom",
            action: (editor) => {
                // Add your own code
            },
            className: "fa fa-star",
            title: "Custom Button",
            attributes: { // for custom attributes
                id: "custom-id",
                "data-value": "custom value" // HTML5 data-* attributes need to be enclosed in quotation marks ("") because of the dash (-) in its name.
            }
        },
        "|" // Separator
        // [, ...]
    ]
});

Put some buttons on dropdown menu

const easyMDE = new EasyMDE({
    toolbar: [{
                name: "heading",
                action: EasyMDE.toggleHeadingSmaller,
                className: "fa fa-header",
                title: "Headers",
            },
            "|",
            {
                name: "others",
                className: "fa fa-blind",
                title: "others buttons",
                children: [
                    {
                        name: "image",
                        action: EasyMDE.drawImage,
                        className: "fa fa-picture-o",
                        title: "Image",
                    },
                    {
                        name: "quote",
                        action: EasyMDE.toggleBlockquote,
                        className: "fa fa-percent",
                        title: "Quote",
                    },
                    {
                        name: "link",
                        action: EasyMDE.drawLink,
                        className: "fa fa-link",
                        title: "Link",
                    }
                ]
            },
        // [, ...]
    ]
});

Keyboard shortcuts

EasyMDE comes with an array of predefined keyboard shortcuts, but they can be altered with a configuration option. The list of default ones is as follows:

Shortcut (Windows / Linux)Shortcut (macOS)Action
Ctrl-'Cmd-'"toggleBlockquote"
Ctrl-BCmd-B"toggleBold"
Ctrl-ECmd-E"cleanBlock"
Ctrl-HCmd-H"toggleHeadingSmaller"
Ctrl-ICmd-I"toggleItalic"
Ctrl-KCmd-K"drawLink"
Ctrl-LCmd-L"toggleUnorderedList"
Ctrl-PCmd-P"togglePreview"
Ctrl-Alt-CCmd-Alt-C"toggleCodeBlock"
Ctrl-Alt-ICmd-Alt-I"drawImage"
Ctrl-Alt-LCmd-Alt-L"toggleOrderedList"
Shift-Ctrl-HShift-Cmd-H"toggleHeadingBigger"
F9F9"toggleSideBySide"
F11F11"toggleFullScreen"

Here is how you can change a few, while leaving others untouched:

const editor = new EasyMDE({
    shortcuts: {
        "toggleOrderedList": "Ctrl-Alt-K", // alter the shortcut for toggleOrderedList
        "toggleCodeBlock": null, // unbind Ctrl-Alt-C
        "drawTable": "Cmd-Alt-T", // bind Cmd-Alt-T to drawTable action, which doesn't come with a default shortcut
    }
});

Shortcuts are automatically converted between platforms. If you define a shortcut as "Cmd-B", on PC that shortcut will be changed to "Ctrl-B". Conversely, a shortcut defined as "Ctrl-B" will become "Cmd-B" for Mac users.

The list of actions that can be bound is the same as the list of built-in actions available for toolbar buttons.

Advanced use

Event handling

You can catch the following list of events: https://codemirror.net/doc/manual.html#events

const easyMDE = new EasyMDE();
easyMDE.codemirror.on("change", () => {
    console.log(easyMDE.value());
});

Removing EasyMDE from text area

You can revert to the initial text area by calling the toTextArea method. Note that this clears up the autosave (if enabled) associated with it. The text area will retain any text from the destroyed EasyMDE instance.

const easyMDE = new EasyMDE();
// ...
easyMDE.toTextArea();
easyMDE = null;

If you need to remove registered event listeners (when the editor is not needed anymore), call easyMDE.cleanup().

Useful methods

The following self-explanatory methods may be of use while developing with EasyMDE.

const easyMDE = new EasyMDE();
easyMDE.isPreviewActive(); // returns boolean
easyMDE.isSideBySideActive(); // returns boolean
easyMDE.isFullscreenActive(); // returns boolean
easyMDE.clearAutosavedValue(); // no returned value

How it works

EasyMDE is a continuation of SimpleMDE.

SimpleMDE began as an improvement of lepture's Editor project, but has now taken on an identity of its own. It is bundled with CodeMirror and depends on Font Awesome.

CodeMirror is the backbone of the project and parses much of the Markdown syntax as it's being written. This allows us to add styles to the Markdown that's being written. Additionally, a toolbar and status bar have been added to the top and bottom, respectively. Previews are rendered by Marked using GitHub Flavored Markdown (GFM).

SimpleMDE fork

I originally made this fork to implement FontAwesome 5 compatibility into SimpleMDE. When that was done I submitted a pull request, which has not been accepted yet. This, and the project being inactive since May 2017, triggered me to make more changes and try to put new life into the project.

Changes include:

  • FontAwesome 5 compatibility
  • Guide button works when editor is in preview mode
  • Links are now https:// by default
  • Small styling changes
  • Support for Node 8 and beyond
  • Lots of refactored code
  • Links in preview will open in a new tab by default
  • TypeScript support

My intention is to continue development on this project, improving it and keeping it alive.

Hacking EasyMDE

You may want to edit this library to adapt its behavior to your needs. This can be done in some quick steps:

  1. Follow the prerequisites and installation instructions in the contribution guide;
  2. Do your changes;
  3. Run gulp command, which will generate files: dist/easymde.min.css and dist/easymde.min.js;
  4. Copy-paste those files to your code base, and you are done.

Contributing

Want to contribute to EasyMDE? Thank you! We have a contribution guide just for you!


Author: Ionaru
Source Code: https://github.com/Ionaru/easy-markdown-editor
License: MIT license

#react-native #react 

Iliana  Welch

Iliana Welch

1595249460

Docker Explained: Docker Architecture | Docker Registries

Following the second video about Docker basics, in this video, I explain Docker architecture and explain the different building blocks of the docker engine; docker client, API, Docker Daemon. I also explain what a docker registry is and I finish the video with a demo explaining and illustrating how to use Docker hub

In this video lesson you will learn:

  • What is Docker Host
  • What is Docker Engine
  • Learn about Docker Architecture
  • Learn about Docker client and Docker Daemon
  • Docker Hub and Registries
  • Simple demo to understand using images from registries

#docker #docker hub #docker host #docker engine #docker architecture #api

Docker manifest - A peek into image's manifest.json files

docker manifest – An experimental feature !

The image manifest provides a configuration and a set of layers for a container image.

This is an experimental feature. To enable this feature in the Docker CLI, one can edit the config.json file found in ~/.docker/config.json like :

{
        "auths": {
                "https://index.docker.io/v1/": {
                        "auth": "XXXXXXX"
                }
        },
        "HttpHeaders": {
                "User-Agent": "Docker-Client/19.03.8 (linux)"
        },
        "experimental": "enabled",
        "debug": true
}

What is ‘docker manifest’ ?

The docker manifest command does not work independently to perform any action. In order to work with the docker manifest or manifest list, we use sub-commands along with it. This manifest sub-command can enable us to interact with the image manifests. Furthermore, it also gives information about the OS and the architecture, that a particular image was built for.

A single manifest comprises of information about an image, it’s size, the layers and digest.

A manifest list is a list of image layers (manifests) that are, created by specifying one or more image names. It can then be used in the same way as an image name in docker pull and docker run commands.

Commands to get started with :

After enabling this feature, one would be able to access the following command :

docker-manifest-enter image description here

These commands are easy to use. It basically avoids the need for pulling and running and then testing the images locally, from a docker registry.

Next, to inspect an image manifest, follow this syntax,

 docker manifest inspect image-name

enter image description here

.

#devops #docker #devops #docker #docker learning #docker-image

Docker creating an image | Build and run your image | Docker Fundamentals

Docker create an image from a container | Creating your own image | How to create Docker Image from a Container and Dockerfile.

#docker #image #dockers

August  Murray

August Murray

1615158300

Tips for Optimizing Docker Builds

In this post, I’m going to address a few often-overlooked concepts that will help with optimizing the Docker image development and build process.

Docker images are used as the primary image in the Docker executor. They are the blueprints for containers, providing the instructions for how a container is spawned. In this post, I’m going to address a few often-overlooked concepts that will help with optimizing the Docker image development and build process.

How Do You Build a Docker Image?

Let’s start with a brief description of the Docker build process. It is a process triggered by running the docker build command using the Docker CLI tool.

The docker build command builds a Docker image based on the instructions specified in a file known as a Dockerfile. The Dockerfile is a text document that contains all the ordered commands a user would call on the command line to assemble an image.

A Docker image consists of read-only layers. Each layer represents a Dockerfile instruction. The layers are stacked, and each one is a delta of the changes from the previous layer. I think of these layers as a form of cache. Updates are only made to the layers that change versus updating every layer on every change.

The example below depicts the contents of a Dockerfile:

Each instruction in this file represents a separate layer in a Docker image. Below is a brief explanation of each instruction:

  • FROM creates a layer from the ubuntu:18.04 Docker image
  • COPY adds files from your Docker client’s current directory
  • RUN builds your application with make
  • CMD specifies what command to run within the container

These four commands will create layers in Docker images when they are executed during the build process.

If you’re interested in learning more about images and layers, you can read about them here.

#cloud #docker #docker image #image building