Mention SSH server requirement for JetBrains and CLI (github#32024)

content/codespaces/developing-in-codespaces/creating-a-codespace.md

@@ -17,7 +17,7 @@ shortTitle: Create a codespace
 
 ## About codespace creation
 
-You can create a codespace on {% data variables.product.prodname_dotcom_the_website %}, in {% data variables.product.prodname_vscode %}, or by using {% data variables.product.prodname_cli %}. Use the tabs in this article to display instructions for each of these ways of creating a codespace.
+{% data reusables.codespaces.ways-to-create-a-codespace %} Use the tabs in this article to display instructions for each of these ways of creating a codespace.
 
 {% note %}
 

content/codespaces/developing-in-codespaces/using-github-codespaces-in-your-jetbrains-ide.md

@@ -41,6 +41,7 @@ To work in a codespace in a JetBrains IDE you need:
 * A valid JetBrains license
 * The JetBrains Gateway application
 * {% data variables.product.prodname_cli %} version 2.2.0 or later 
+* An existing codespace that's running an SSH server
 
 ### JetBrains license
 
@@ -68,9 +69,17 @@ gh --version
 
 For more information, see "[About GitHub CLI](/github-cli/github-cli/about-github-cli)."
 
-## Authenticating with {% data variables.product.prodname_cli %}
+### Codespace running an SSH server
 
-To use {% data variables.product.prodname_cli %} for {% data variables.product.prodname_github_codespaces %} you must authenticate with {% data variables.product.prodname_dotcom_the_website %}, specifying the `codespace` scope.
+You must have an existing codespace to connect to. {% data reusables.codespaces.ways-to-create-a-codespace %} For more information, see "[Creating a codespace](/codespaces/developing-in-codespaces/creating-a-codespace)."
+
+{% data reusables.codespaces.ssh-server-installed %}
+
+For more information about the `devcontainer.json` file and the default container image, see "[Introduction to dev containers](/codespaces/setting-up-your-project-for-codespaces/introduction-to-dev-containers)."
+
+## Authenticating with {% data variables.product.prodname_dotcom_the_website %}
+
+Before you can use the JetBrains Gateway to connect to your codespaces, you must use {% data variables.product.prodname_cli %} to authenticate with {% data variables.product.prodname_dotcom_the_website %}, specifying the `codespace` scope.
 
 1. In a terminal window:
 

content/codespaces/developing-in-codespaces/using-github-codespaces-with-github-cli.md

@@ -117,6 +117,14 @@ To run commands on the remote codespace machine, from your terminal, you can SSH
 gh codespace ssh -c CODESPACE-NAME
 ```
 
+{% note %}
+
+**Note**: {% data reusables.codespaces.ssh-server-installed %}
+
+<br>For more information about the `devcontainer.json` file and the default container image, see "[Introduction to dev containers](/codespaces/setting-up-your-project-for-codespaces/introduction-to-dev-containers)."
+
+{% endnote %}
+
 {% data variables.product.prodname_github_codespaces %} copies your GitHub SSH keys into the codespace on creation for a seamless authentication experience. You may be asked to enter the passphrase for your SSH key, after which you will get a command prompt from the remote codespace machine.
 
 If you don't have any SSH keys, follow the instructions in "[Generating a new SSH key and adding it to the ssh-agent](/authentication/connecting-to-github-with-ssh/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent)."

data/reusables/codespaces/ssh-server-installed.md

@@ -0,0 +1,11 @@
+The codespace you connect to must be running an SSH server. The default container image includes an SSH server, which is started automatically. If your codespaces are not created from the default image, you can install and start an SSH server by adding the following to the `features` object in your `devcontainer.json` file.
+
+```json
+"features": {
+    ...
+    "ghcr.io/devcontainers/features/sshd:1": {
+        "version": "latest"
+    },
+    ...
+}
+```

data/reusables/codespaces/ways-to-create-a-codespace.md

@@ -0,0 +1 @@
+You can create a codespace on {% data variables.product.prodname_dotcom_the_website %}, in {% data variables.product.prodname_vscode %}, or by using {% data variables.product.prodname_cli %}.