Support multiple workers in a single Miniflare instance #7251
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A wrangler prerelease is available for testing. You can install this latest build in your project with: npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-wrangler-7251You can reference the automatically updated head of this PR with: npm install --save-dev https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/prs/7251/npm-package-wrangler-7251Or you can use npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-wrangler-7251 dev path/to/script.jsAdditional artifacts:npx https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-create-cloudflare-7251 --no-auto-updatenpm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-cloudflare-kv-asset-handler-7251npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-miniflare-7251npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-cloudflare-pages-shared-7251npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-cloudflare-vitest-pool-workers-7251npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-cloudflare-workers-editor-shared-7251npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-cloudflare-workers-shared-7251npm install https://prerelease-registry.devprod.cloudflare.dev/workers-sdk/runs/11964785987/npm-package-cloudflare-workflows-shared-7251Note that these links will no longer work once the GitHub Actions artifact expires.
Please ensure constraints are pinned, and |
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What would we need in order for this to work without the (not saying we need to solve for it rn, just curious what the config decision we're facing is) |
Yeah, something like |
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The problem with adding a new field to services in wrangler.toml is that you're then encoding this idea of a primary worker, whereas you might want to start up one of the bound workers as a primary worker to work with it directly. It might be useful also to think about a true multi-worker config, where you don't have a single primary worker, and where you can start any of the defined workers as the primary. E.g.: {
...
workers: [
{
name: "a",
main: "../a/a.ts",
bindings: { c: { "type": "worker", name: "c" } },
},
{
name: "b",
main: "../b/b.ts",
bindings: { c: { "type": "worker", name: "c" } },
},
{
name: "c",
main: "../c/c.ts",
},
]
}# starts worker "a" at http:localhost:8787 with "c" accessible only through RPC
npx wrangler dev --worker a
# starts worker "b" at http:localhost:8787 with "c" accessible only through RPC
npx wrangler dev --worker b
# starts worker "c" at http:localhost:8787
npx wrangler dev --worker cMulti-worker is a new paradigm for (I don't say the above to derail the PR - @penalosa's solution is a neat and flexible one that doesn't tie us to any future arrangement). |
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This is amazing work - very nice observation that we essentially already have this functionality in Miniflare and it just needed hooking up 👍
Let's start the conversation on whether or not users will still want/need workers to be accessed from distinct endpoints, or if the dev registry is something we could remove entirely (perhaps in v4?).
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Might be good to test some failure cases here.
- What if a bound worker fails - do calls return the right response?
- What if the primary worker fails - do the bound workers shut down correctly?
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I feel like we could clean things up if we just treated all scenarios as multi-worker. So instead of having a separate MultiworkerRuntimeController, just modify the LocalRuntimeController to handle multi-workers, and then cast the configPath to an array in the yargs definition.
const configs = Array.isArray(configPath) ? configPath : [configPath];
// Now no need to handle the single worker case. LocalRuntimeController assumes multi.
const runtime = new LocalRuntimeController(configs.length);Or is there a reason to keep the single worker code path?
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I went down this path in Merge Local & Multi controllers, but I'm starting to get a bit concerned about the potential for disrupting the normal dev flow, and I think it might end up being more complexity than it's worth. The single worker dev flow has two runtimes, remote & local, and the remote runtime doesn't (and will never) work for the multiworker use case. Because of that there's some differences in how these flows are set up (as well as the disabling of the dev registry in the multiworker flow, which involves disabling the registry as well as a change to how DOs & entrypoints are registered). It's not that much duplicated code, and I think it's actually clearer to keep them separate, and easier to reason about. What do you think?
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does this support pages , i tried |
This PR allows you to run multiple workers in a single Miniflare instance, allowing for cross-service RPC without the complexities of the dev registry. To try it out, pass multiple
-cflags to Wrangler: i.e.wrangler dev -c wrangler.toml -c ../other-worker/wrangler.toml. The first config will be treated as the primary worker and will be exposed over HTTP as usual (localhost:8787) while the rest will be treated as secondary and will only be accessible via a service binding from the primary worker.