timtinkers.online
posts "question of the day" to a discord webhook
Double post mitigation with stored execution date in KV
+42
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+42
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main.ts
+42
-14
main.ts
···
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// @ts-ignore Deno.cron is unstable, run with --unstable-cron flag
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Deno.cron("QOTD", Deno.env.get("CRON_STRING"), async () => {
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// Fetch data
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const response = await fetch(endpoint);
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const { data } = await response.json();
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// Open KV and fetch last index
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// @ts-ignore Deno.openKv is unstable, run with --unstable-kv flag
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const kv = await Deno.openKv(
···
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// Deno.env.get("DENO_KV_DATABASE_ID")
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// }/connect`,
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);
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const current = await kv.get<number>(["lastIndex"]);
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const index = current.value ?? 0;
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const nextIndex = (index + 1) % data.length;
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// Perform atomic operation to update index
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// Create a key based on the current day (YYYY-MM-DD)
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const today = new Date().toISOString().split("T")[0];
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const executionKey = ["qotd_execution", today];
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+
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// Check if we've already executed today
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const existingExecution = await kv.get(executionKey);
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if (existingExecution.value) {
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console.log(`Already executed QOTD for ${today}, skipping`);
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return;
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}
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// Try to claim today's execution
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const result = await kv.atomic()
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.check(current) // Ensure the value hasn't changed
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.set(["lastIndex"], nextIndex)
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.check(existingExecution) // Ensure no one else claimed it
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.set(executionKey, {
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timestamp: Date.now(),
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instanceId: crypto.randomUUID(),
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})
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.commit();
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if (!result.ok) {
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console.log("Another instance already updated the index, skipping");
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console.log("Another instance claimed today's execution, skipping");
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return;
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}
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// Post to Discord webhook
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await sendDiscordNotification(data[index].question);
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console.log(`Cron: posted question of index ${index} to Discord.`);
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try {
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// Fetch data
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const response = await fetch(endpoint);
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const { data } = await response.json();
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+
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// Get and update index
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const indexResult = await kv.get<number>(["lastIndex"]);
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const index = indexResult.value ?? 0;
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const nextIndex = (index + 1) % data.length;
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// Post to Discord
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await sendDiscordNotification(data[index].question);
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console.log(
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`Cron: posted question of index ${index} to Discord for ${today}`,
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);
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// Update index
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await kv.set(["lastIndex"], nextIndex);
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} catch (error) {
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// If we fail, remove our claim so another instance can try
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await kv.delete(executionKey);
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console.error("Error in cron job:", error);
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throw error;
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}
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});