401 Error on CloudKit Server-to-Server Authentication on Node JS - cloudkit

Question

I'm trying to query my public CloudKit database using server-to-server authentication. I've generated the key according to Apple's docs, but no matter what I do I get this error:
401 - Unauthorized
data: {
uuid: '...',
serverErrorCode: 'AUTHENTICATION_FAILED',
reason: 'no auth method found'
}
As far as I can tell, I've set everything up per the docs, but obviously I'm doing something wrong. Here's what I've got in my Node app so far:
let date = moment().format('YYYY-MM-DD[T]HH:mm:ss[Z]')
let domain = 'https://api.apple-cloudkit.com'
let subpath = '/database/1/iCloud.<my container>/development/public/users/current'
let key = fs.readFileSync(__dirname +'/../eckey.pem', 'utf8')
let keyID = 'abc123...'
let requestBody = ''
let bodyHash = crypto.createHash('SHA256').update(requestBody).digest('base64')
let message = date+':'+bodyHash+':'+subpath
let signature = crypto.createSign('RSA-SHA256').update(message).sign(key, 'base64')
let headers = {
'X-Apple-CloudKit-Request-KeyID': keyID,
'X-Apple-CloudKit-Request-ISO8601Date': date,
'X-Apple-CloudKit-Request-SignatureV1': signature
}
try{
await axios.post(domain+subpath, requestBody, { headers: headers })
console.log('--- :) ---')
}catch(error){
console.log('=== :( ===')
console.log(error)
}
I've already reviewed this helpful SO post, but I'm still stuck.
Can anyone see what I might be doing wrong?

Answer 1

I had to do a ton of troubleshooting to figure this out, but for the sake of posterity, here's what I had wrong:
=== Fix # 1 ===
My date was generating local time which was inaccurate because the format implies Zulu/UTC time (because of the Z).
The fix was to add .utc() to the Moment:
let date = moment().utc().format('YYYY-MM-DD[T]HH:mm:ss[Z]')
=== Fix # 2 ===
Apparently Axios didn't like how I was formatting the request. Changing it to this (with the baseURL and url separate) works:
let response = await axios({
method: 'post',
baseURL: baseURL,
url: '/records/modify',
data: query,
headers: headers
})
Seems to be working great now with these fixes in place.