Reattempt PREVIEW_URL fetch on failure

entrypoint.sh

@@ -35,15 +35,23 @@ for endpoint in endpoints:
 END
 }
 
-PREVIEW_URL=$(get_workspace_url_prefix "$CHE_WORKSPACE_NAMESPACE-che") # Che 7 OPS configuration where the (actual) namespace is "<username>-che"
-if test -z "$PREVIEW_URL" 
-then
-    PREVIEW_URL=$(get_workspace_url_prefix "$CHE_WORKSPACE_NAMESPACE-$CHE_WORKSPACE_ID") # Che 7 UAT configuration fallback where the default namespace is "<username>-<workspaceid>", this will be deprecated
-fi
-if test -z "$PREVIEW_URL" 
-then
-    PREVIEW_URL=$(get_workspace_url_prefix "$CHE_WORKSPACE_ID") # Che 6 configuration fallback where the default namespace is the workspace id, this will be deprecated
-fi
+for i in {0..20}
+do 
+    echo "Attempt $i to construct PREVIEW_URL"
+    PREVIEW_URL=$(get_workspace_url_prefix "$CHE_WORKSPACE_NAMESPACE-che") # Che 7 OPS configuration where the (actual) namespace is "<username>-che"
+    if test -z "$PREVIEW_URL" 
+    then
+        PREVIEW_URL=$(get_workspace_url_prefix "$CHE_WORKSPACE_NAMESPACE-$CHE_WORKSPACE_ID") # Che 7 UAT configuration fallback where the default namespace is "<username>-<workspaceid>", this will be deprecated
+    fi
+    if test -z "$PREVIEW_URL" 
+    then
+        PREVIEW_URL=$(get_workspace_url_prefix "$CHE_WORKSPACE_ID") # Che 6 configuration fallback where the default namespace is the workspace id, this will be deprecated
+    fi
+    if ! test -z "$PREVIEW_URL" # exit loop when it has a preview_url
+    then
+        break
+    fi
+done
 
 # Fix Jupyterlab for Che in `single-host` mode. In `single-host` mode, Che uses URL path prefixes
 # to distinguish workspaces. So for example, `https://<host>/work/space/path/<jupyter endpoints>`.