feat: add path-based sharing for kasm (#115)

angrycub · matifali · web-flow · commit c5a21e07a481 · 2025-05-30T21:09:27.000+05:00
Co-authored-by: Atif Ali &lt;atif@coder.com&gt;
diff --git a/registry/coder/modules/kasmvnc/README.md b/registry/coder/modules/kasmvnc/README.md
@@ -15,9 +15,10 @@ Automatically install [KasmVNC](https://kasmweb.com/kasmvnc) in a workspace, and
 module "kasmvnc" {
   count               = data.coder_workspace.me.start_count
   source              = "registry.coder.com/coder/kasmvnc/coder"
-  version             = "1.0.23"
+  version             = "1.1.0"
   agent_id            = coder_agent.example.id
   desktop_environment = "xfce"
+  subdomain           = true
 }
 ```
 
diff --git a/registry/coder/modules/kasmvnc/main.tf b/registry/coder/modules/kasmvnc/main.tf
@@ -29,32 +29,42 @@ variable "kasm_version" {
 variable "desktop_environment" {
   type        = string
   description = "Specifies the desktop environment of the workspace. This should be pre-installed on the workspace."
+
   validation {
     condition     = contains(["xfce", "kde", "gnome", "lxde", "lxqt"], var.desktop_environment)
     error_message = "Invalid desktop environment. Please specify a valid desktop environment."
   }
 }
 
+variable "subdomain" {
+  type        = bool
+  default     = true
+  description = "Is subdomain sharing enabled in your cluster?"
+}
+
 resource "coder_script" "kasm_vnc" {
   agent_id     = var.agent_id
   display_name = "KasmVNC"
   icon         = "/icon/kasmvnc.svg"
+  run_on_start = true
   script = templatefile("${path.module}/run.sh", {
-    PORT : var.port,
-    DESKTOP_ENVIRONMENT : var.desktop_environment,
-    KASM_VERSION : var.kasm_version
+    PORT                = var.port,
+    DESKTOP_ENVIRONMENT = var.desktop_environment,
+    KASM_VERSION        = var.kasm_version
+    SUBDOMAIN           = tostring(var.subdomain)
+    PATH_VNC_HTML       = var.subdomain ? "" : file("${path.module}/path_vnc.html")
   })
-  run_on_start = true
 }
 
 resource "coder_app" "kasm_vnc" {
   agent_id     = var.agent_id
   slug         = "kasm-vnc"
-  display_name = "kasmVNC"
+  display_name = "KasmVNC"
   url          = "http://localhost:${var.port}"
   icon         = "/icon/kasmvnc.svg"
-  subdomain    = true
+  subdomain    = var.subdomain
   share        = "owner"
+
   healthcheck {
     url       = "http://localhost:${var.port}/app"
     interval  = 5
diff --git a/registry/coder/modules/kasmvnc/path_vnc.html b/registry/coder/modules/kasmvnc/path_vnc.html
@@ -0,0 +1,81 @@
+<!DOCTYPE html>
+<html>
+  <head>
+    <title>Path-Sharing Bounce Page</title>
+    <style type="text/css">
+      :root {
+        color-scheme: light dark;
+        --dark: #121212;
+        --header-bg: rgba(127,127,127,0.2);
+        --light: white;
+        --rule-color: light-dark(rgba(0,0,0,0.8), rgba(255,255,255,0.8));
+        background-color: light-dark(var(--light), var(--dark));
+        color: light-dark(var(--dark), var(--light));
+      }
+      body, h1, p {
+        box-sizing: border-box;
+        margin:0; padding:0;
+      }
+      body{
+        font-family:Inter, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
+      }
+      h1{
+        width: 100%;
+        padding: 1rem;
+        letter-spacing: -1.5pt;
+        padding-bottom:10px;
+        border-bottom: 1px solid var(--rule-color);
+        background-color: var(--header-bg);
+      }
+      p {
+        padding: 1rem; letter-spacing: -0.5pt;}
+      a.indent { display:inline-block; padding-top:0.5rem; padding-left: 2rem; font-size:0.8rem }
+      </style>
+    <meta charset="UTF-8" />
+  </head>
+  <body>
+    <h1>Path-Sharing Bounce Page</h1>
+    <p>
+      This application is being served via path sharing.
+      If you are not redirected, <span id="help">check the
+      Javascript console in your browser's developer tools
+      for more information.</span>
+    </p>
+  </body>
+  <script language="javascript">
+    // This page exists to satisfy the querystring driven client API
+    // specified here - https://raw.githubusercontent.com/kasmtech/noVNC/bce2d6a7048025c6e6c05df9d98b206c23f6dbab/docs/EMBEDDING.md
+    // tl;dr:
+    // * `host` - The WebSocket host to connect to.
+    //      This is just the hostname component of the original URL
+    // * `port` - The WebSocket port to connect to.
+    //      It doesn't look like we need to set this unless it's different
+    //      than the incoming http request.
+    // * `encrypt` - If TLS should be used for the WebSocket connection.
+    //      we base this on whether or not the protocol is `https`, seems
+    //      reasonable for now.
+    // * `path` - The WebSocket path to use.
+    //      This apparently doesn't tolerate a leading `/` so we use a
+    //      function to tidy that up.
+    function trimFirstCharIf(str, char) {
+       return str.charAt(0) === char ? str.slice(1) : str;
+    }
+    function trimLastCharIf(str, char) {
+       return str.endsWith("/") ? str.slice(0,str.length-1) : str;
+    }
+    const newloc = new URL(window.location);
+    const h = document.getElementById("help")
+
+    // Building the websockify path must happen before we append the filename to newloc.pathname
+    newloc.searchParams.append("path",
+      trimLastCharIf(trimFirstCharIf(newloc.pathname,"/"),"/")+"/websockify");
+    newloc.searchParams.append("encrypted", newloc.protocol==="https:"? true : false);
+
+    newloc.pathname += "vnc.html"
+    console.log(newloc);
+
+    h.innerHTML = `click <a id="link" href="${newloc.toString()}">here</a> to go to the application.
+    <br/><br/>The rewritten URL is:<br/><a id="link" class="indent" href="${newloc.toString()}">${newloc.toString()}</a>`
+    window.location = newloc.href;
+  </script>
+</html>
diff --git a/registry/coder/modules/kasmvnc/run.sh b/registry/coder/modules/kasmvnc/run.sh
@@ -3,6 +3,8 @@
 # Exit on error, undefined variables, and pipe failures
 set -euo pipefail
 
+error() { printf "💀 ERROR: %s\n" "$@"; exit 1; }
+
 # Function to check if vncserver is already installed
 check_installed() {
   if command -v vncserver &> /dev/null; then
@@ -188,7 +190,7 @@ if command -v sudo &> /dev/null && sudo -n true 2> /dev/null; then
   SUDO=sudo
 else
   kasm_config_file="$HOME/.vnc/kasmvnc.yaml"
-  SUDO=
+  SUDO=""
 
   echo "WARNING: Sudo access not available, using user config dir!"
 
@@ -206,6 +208,7 @@ echo "Writing KasmVNC config to $kasm_config_file"
 $SUDO tee "$kasm_config_file" > /dev/null << EOF
 network:
   protocol: http
+  interface: 127.0.0.1
   websocket_port: ${PORT}
   ssl:
     require_ssl: false
@@ -220,16 +223,82 @@ EOF
 # and does not listen publicly
 echo -e "password\npassword\n" | vncpasswd -wo -u "$USER"
 
+get_http_dir() {
+  # determine the served file path
+  # Start with the default
+  httpd_directory="/usr/share/kasmvnc/www"
+
+  # Check the system configuration path
+  if [[ -e /etc/kasmvnc/kasmvnc.yaml ]]; then
+    d=($(grep -E "^\s*httpd_directory:.*$" /etc/kasmvnc/kasmvnc.yaml))
+    # If this grep is successful, it will return:
+    #     httpd_directory: /usr/share/kasmvnc/www
+    if [[ $${#d[@]} -eq 2 && -d "$${d[1]}" ]]; then
+      httpd_directory="$${d[1]}"
+    fi
+  fi
+
+  # Check the home directory for overriding values
+  if [[ -e "$HOME/.vnc/kasmvnc.yaml" ]]; then
+    d=($(grep -E "^\s*httpd_directory:.*$" /etc/kasmvnc/kasmvnc.yaml))
+    if [[ $${#d[@]} -eq 2 && -d "$${d[1]}" ]]; then
+      httpd_directory="$${d[1]}"
+    fi
+  fi
+  echo $httpd_directory
+}
+
+fix_server_index_file(){
+    local fname=$${FUNCNAME[0]}  # gets current function name
+    if [[ $# -ne 1 ]]; then
+        error "$fname requires exactly 1 parameter:\n\tpath to KasmVNC httpd_directory"
+    fi
+    local httpdir="$1"
+    if [[ ! -d "$httpdir" ]]; then
+      error "$fname: $httpdir is not a directory"
+    fi
+    pushd "$httpdir" > /dev/null
+
+    cat <<'EOH' > /tmp/path_vnc.html
+${PATH_VNC_HTML}
+EOH
+    $SUDO mv /tmp/path_vnc.html .
+    # check for the switcheroo
+    if [[ -f "index.html" && -L "vnc.html" ]]; then
+      $SUDO mv $httpdir/index.html $httpdir/vnc.html
+    fi
+    $SUDO ln -s -f path_vnc.html index.html
+    popd > /dev/null
+}
+
+patch_kasm_http_files(){
+  homedir=$(get_http_dir)
+  fix_server_index_file "$homedir"
+}
+
+if [[ "${SUBDOMAIN}" == "false" ]]; then
+  echo "🩹 Patching up webserver files to support path-sharing..."
+  patch_kasm_http_files
+fi
+
+VNC_LOG="/tmp/kasmvncserver.log"
 # Start the server
 printf "🚀 Starting KasmVNC server...\n"
-vncserver -select-de "${DESKTOP_ENVIRONMENT}" -disableBasicAuth > /tmp/kasmvncserver.log 2>&1 &
-pid=$!
-
-# Wait for server to start
-sleep 5
-grep -v '^[[:space:]]*$' /tmp/kasmvncserver.log | tail -n 10
-if ps -p $pid | grep -q "^$pid"; then
-  echo "ERROR: Failed to start KasmVNC server. Check full logs at /tmp/kasmvncserver.log"
+
+set +e
+vncserver -select-de "${DESKTOP_ENVIRONMENT}" -disableBasicAuth > "$VNC_LOG" 2>&1
+RETVAL=$?
+set -e
+
+if [[ $RETVAL -ne 0 ]]; then
+  echo "ERROR: Failed to start KasmVNC server. Return code: $RETVAL"
+    if [[ -f "$VNC_LOG" ]]; then
+    echo "Full logs:"
+    cat "$VNC_LOG"
+  else
+    echo "ERROR: Log file not found: $VNC_LOG"
+  fi
   exit 1
 fi
+
 printf "🚀 KasmVNC server started successfully!\n"
