If you are already using Gantt-Chart for Jira Cloud, you may want to embed your Gantt diagrams in a Confluence page as well: that's pretty easy using the following steps for configuration, once.

Instructions

1. Confluence Cloud: install app "Gantt-Chart for Jira in Confluence (part 1/2)" from the Atlassian Marketplace as admin including a valid license.
2. Confluence Cloud: install app "Gantt-Chart for Jira in Confluence (part 2/2, CORE)" from https://www.polscheit.de/plugins/jira/gantt-chart/cloud as described below:
   1. switch into Confluence Administration on page "Manage apps" as system admin
   2. click on "Settings" at the bottom of the page "Manage apps": a pop-up occurs with additional options
   3. enable development mode via the checkbox as displayed below and commit by clicking on the button "Apply" at the bottom of the pop-up:
      
      
      Development mode allows the installation of Atlassian Connect app descriptors that are not from the Atlassian Marketplace.
      
   4. then reload that page e.g. hit F5. Now, you should see the additional link text "Upload app" like shown below:
      
      
      
   5. click on the link "Upload app" on your page "Manage apps"
   6. enter the following URL into the input field of the occurring pop-up:
      
      https://www.polscheit.de/plugins/jira/gantt-chart/cloud/atlassian-connect-confluence-core.json
      
      
   7. commit by clicking on the button "Upload"

Usage

1. Now, you can add "Gantt-Chart" as a macro on any Confluence page specifying the related Jira project to be displayed.
2. Additionally, you have to add the macro "Gantt-Chart enabled" provided by the app "Gantt-Chart for Jira in Confluence (part 1/2)" via the Atlassian Marketplace.
   Generally, this macro is not listed if you click on "+": you have to choose "Other macros", click on section "External-content" and select "Gantt-Chart enabled".

If you are already using the new page layout of Confluence, then it looks a little bit different:

Regardless, if you click on "Other macros" or "View macros", in both cases you can search for "Gantt" to immediately see both necessary macros:

This results in an embedded Gantt-Chart on your Confluence page:

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LIVE sample

Embedded Gantt-Chart from my Jira Cloud, here: