Recently, a ticket came through regarding a user who wanted to deploy a Node.js frontend, but alongside a Flutter backend, and it that was something that was possible on Platform.sh/Upsun.
Youbetcha!
Deploying
To get started locally (I was on a Mac), I ran:
I found a (now archived, but still useful) example repository at https://github.com/flutter/gallery, which showcases a number of example views and components.
mkdir .upsun
touch .upsun/config.yaml
Create a new project (upsun project:create) and connect to the remote when prompted. Then edit the .upsun/config.yaml file to contain the following:
gallery:
variables:
env:
FLUTTER_VERSION_DL: “3.22.2″
source:
root: “gallery”
type: “nodejs:20″
hooks:
build: |
set -eux
curl -s
https://storage.googleapis.com/flutter_infra_release/releases/stable/linux/flutter_linux_$FLUTTER_VERSION_DL-stable.tar.xz
-o flutter.tar.xz
tar -xf $PLATFORM_APP_DIR/flutter.tar.xz -C .
export PATH=”$PLATFORM_APP_DIR/flutter/bin:$PATH”
flutter build web
web:
locations:
/:
root: build/web
index:
– index.html
expires: 2m
scripts: false
allow: true
rules:
static/*:
expires: 365d
routes:
“https://{default}/”:
id: gallery
type: upstream
primary: true
upstream: “gallery:http”
“https://www.{default}”:
id: gallery-redirect
type: redirect
to: “https://{default}/”
Flutter is downloaded during the build hook, so the choice of type is largely arbitrary at this point. In this example, the most recent version (3.22.2) is used and set to the environment variable FLUTTER_VERSION_DL so that it can be downloaded. Finally, the command flutter build web actually downloads dependencies and builds the application
With this configuration file now in hand, we can commit and push to Upsun:
upsun push
And that’s it! The configuration shown here works for many Flutter apps, including all of the examples in https://github.com/gskinnerTeam/flutter_vignettes.
Next steps
Caching the install. Upsun provides a super flexible build process that’s both completely configuration and smart enough to understand when a commit has been pushed that actually requires to rebuild an application. That assumption won’t hold true for our downloads of Flutter though — that is, we will redownload Flutter every time a commit requires a new build image, even if we want to continue to use the same version of Flutter. This build hook could be improved by utilizing Upsun’s build cache to double check if the version has been edited by us, or otherwise reuse a cached download, which will save us some time.
Nix. A great thing that’s come out recently on Upsun is support for Nix via our composable image syntax. In the example so far, we used the legacy type: “node:20” syntax, which pulls one of our maintained image versions. Instead, we could configure the project like this:
gallery:
source:
root: “gallery”
stack:
– “flutter”
Where the stack entry “flutter” pulls the most recent version from Nix Packages.
Seeing as Upsun Nix support doesn’t yet allow for the kind of version pinning we might want in Beta, we’ll just have to hold off on that experiment until next time!
Until then, happy deploying!
Chad C.
