feat(cli): Use canary Docker image when using canary CLI client (#1316)

This has been discussed but when using the canary version of the client
it's currently not clear that you should also manually set the
`ELECTRIC_IMAGE` to the canary tag as well - the proposed solution is to
make the CLI automatically detect that and use the appropriate image.

The `LIB_VERSION` generated by the changesets does not update for the
canary releases so I had to use the `package.json` directly, but since
this is for the CLI only (which we are also splitting out of the client)
that should be fine, it's not meant to be browser-runnable code.

This is mostly a quality of life improvement for us developing electric
as the current requirement to remember to point to canary releases for
both the sync service and client is slightly annoying.

.changeset/gold-poets-invent.md

@@ -0,0 +1,5 @@
+---
+"electric-sql": patch
+---
+
+Use canary Docker image tag when using the canary CLI client.

clients/typescript/src/cli/config-options.ts

@@ -6,10 +6,14 @@ import {
   getConfigValue,
   type ConfigMap,
 } from './config'
-import { dedent, getAppName, buildDatabaseURL, parsePgProxyPort } from './util'
-import { LIB_VERSION } from '../version'
-
-const minorVersion = LIB_VERSION.split('.').slice(0, 2).join('.')
+import {
+  dedent,
+  getAppName,
+  buildDatabaseURL,
+  parsePgProxyPort,
+  LIB_MINOR_VERSION,
+  isCanaryRelease,
+} from './util'
 
 // Name will be prefixed with ELECTRIC_ as environment variables.
 export const configOptions: Record<string, any> = {
@@ -312,7 +316,9 @@ export const configOptions: Record<string, any> = {
   ELECTRIC_IMAGE: {
     valueType: String,
     valueTypeName: 'image',
-    defaultVal: `electricsql/electric:${minorVersion}`, // Latest minor version of this library
+    defaultVal: `electricsql/electric:${
+      isCanaryRelease() ? 'canary' : LIB_MINOR_VERSION
+    }`,
     doc: 'The Docker image to use for Electric.',
     groups: ['electric'],
   },

clients/typescript/src/cli/util/index.ts

@@ -2,3 +2,4 @@ export * from './io'
 export * from './parse'
 export * from './string'
 export * from './paths'
+export * from './version'

clients/typescript/src/cli/util/version.ts

@@ -0,0 +1,35 @@
+import fs from 'fs'
+import { LIB_VERSION } from '../../version'
+import path from 'path'
+import { fileURLToPath } from 'url'
+
+/**
+ * Reads and parses the contents of the package.json of the CLI itself
+ */
+function readPackageJson(): Record<string, unknown> {
+  return JSON.parse(
+    fs.readFileSync(
+      path.join(
+        fileURLToPath(import.meta.url),
+        '..',
+        '..',
+        '..',
+        '..',
+        'package.json'
+      ),
+      'utf8'
+    )
+  )
+}
+
+/**
+ * Check whether the CLI is a canary release.
+ *
+ * The LIB_VERSION export does not update for canary releases
+ * so this uses the package.json explicitly for this check
+ */
+export function isCanaryRelease(): boolean {
+  return (readPackageJson().version as string).includes('canary')
+}
+
+export const LIB_MINOR_VERSION = LIB_VERSION.split('.').slice(0, 2).join('.')