SvelteKit Environment Variables with Fly.io Deployment

Real quick! I’m going to go through what I did to get a SvelteKit project deployed to Fly.io and how to set up environment variables. The back story is that I wasn’t getting the best response times from the project I deployed to Vercel for Building Session Analytics with SvelteKit and Turso DB. It was an experiment but still, waiting 6 seconds for a response from the server is not good.

I decide to try out Fly.io and see if I could get better result. There’s a speed run over on the Fly.io docs that get’s you started: https://fly.io/docs/js/frameworks/svelte

This doesn’t cover what you need to do to get environment variables working though.

I followed the steps in the speed run and kept getting errors like this:

#0 5.057 "TURSO_DB_URL" is not exported by "virtual:$env/static/private", imported by "src/lib/turso/client.ts".
#0 5.057 file: /app/src/lib/turso/client.ts:3:1
#0 5.057 1: import {
#0 5.057 2:   TURSO_DB_AUTH_TOKEN,
#0 5.057 3:   TURSO_DB_URL,
#0 5.057      ^
#0 5.057 4: } from '$env/static/private';

I couldn’t get the static private environment variables to work so I decided to try out the dynamic private environment variables.

So, anywhere I was importing the static private environment variables I changed to dynamic private:

-import {
-  TURSO_DB_AUTH_TOKEN,
-  TURSO_DB_URL,
-} from '$env/static/private';
+import { env } from '$env/dynamic/private';
+const { TURSO_DB_AUTH_TOKEN, TURSO_DB_URL } = env;

Then made sure my secrets were available to the fly CLI:

fly secrets set TURSO_DB_URL=secret_token
fly secrets set TURSO_DB_AUTH_TOKEN=secret_token
fly secrets set IPINFO_TOKEN=secret_token

Then I needed to add the secrets to the Docker file created by fly launch:

# ...

# Copy application code
COPY --link . .

# Mount secrets and build application
RUN --mount=type=secret,id=TURSO_DB_AUTH_TOKEN 
    --mount=type=secret,id=TURSO_DB_URL 
    --mount=type=secret,id=IPINFO_TOKEN 
    TURSO_DB_AUTH_TOKEN="$(cat /run/secrets/TURSO_DB_AUTH_TOKEN)" 
    TURSO_DB_URL="$(cat /run/secrets/TURSO_DB_URL)" 
    IPINFO_TOKEN="$(cat /run/secrets/IPINFO_TOKEN)" 
    && pnpm run build

# Remove development dependencies
RUN pnpm prune --prod

# ...

Then deploying again (with fly deploy) worked!

One other thing to note is that the Fly CLI doesn’t seem to pick up the environment variables so I had to add them manually to the fly deploy command each time I want to deploy:

fly deploy --build-secret TURSO_DB_URL="secret_token" --build-secret TURSO_DB_URL="secret_token" --build-secret IPINFO_TOKEN="secret_token"

Update

Another update to this, it seems that the Fly CLI changes a fair bit!

I was getting countless issues with building and not having the secrets available to the Docker build. I found something that worked for me.

So, I had to add the secrets to the Dockerfile ARG TURSO_DB_URL and ARG TURSO_DB_AUTH_TOKEN, then build the app with the tokens RUN TURSO_DB_URL=$TURSO_DB_URL TURSO_DB_AUTH_TOKEN=$TURSO_DB_AUTH_TOKEN pnpm run build:

# syntax = docker/dockerfile:1

# Adjust NODE_VERSION as desired
ARG NODE_VERSION=18.19.0
FROM node:${NODE_VERSION}-slim as base

# Declare build arguments for secrets
ARG TURSO_DB_URL
ARG TURSO_DB_AUTH_TOKEN

LABEL fly_launch_runtime="Node.js"

# Node.js app lives here
WORKDIR /app

# Set production environment
ENV NODE_ENV="production"

# Install pnpm
ARG PNPM_VERSION=8.15.4
RUN npm install -g pnpm@$PNPM_VERSION

# Throw-away build stage to reduce size of final image
FROM base as build

# Install packages needed to build node modules
RUN apt-get update -qq && 
    apt-get install --no-install-recommends -y build-essential node-gyp pkg-config python-is-python3

# Install node modules
COPY --link .npmrc package.json pnpm-lock.yaml ./
RUN pnpm install --frozen-lockfile --prod=false

# Copy application code
COPY --link . .

# Build application using build arguments
RUN TURSO_DB_URL=$TURSO_DB_URL TURSO_DB_AUTH_TOKEN=$TURSO_DB_AUTH_TOKEN pnpm run build

# Remove development dependencies
RUN pnpm prune --prod

# Final stage for app image
FROM base

# Copy built application
COPY --from=build /app /app

# Start the server by default, this can be overwritten at runtime
EXPOSE 3000
CMD [ "pnpm", "run", "start" ]

Then also had to pass them into the fly deploy command:

fly deploy --build-arg TURSO_DB_URL=$TURSO_DB_URL --build-arg TURSO_DB_AUTH_TOKEN=$TURSO_DB_AUTH_TOKEN

😅