经过几天的研究,我终于得到了一个可行的解决方案(移植 Python 实现):
async function getGoogleCredentials(subject: string, scopes: string[]): Promise<JWT | OAuth2Client> {
const auth = new google.auth.GoogleAuth({
scopes: ['https://www.googleapis.com/auth/cloud-platform'],
})
const authClient = await auth.getClient()
if (authClient instanceof JWT) {
return (await new google.auth.GoogleAuth({ scopes, clientOptions: { subject } }).getClient()) as JWT
} else if (authClient instanceof Compute) {
const serviceAccountEmail = (await auth.getCredentials()).client_email
const unpaddedB64encode = (input: string) =>
Buffer.from(input)
.toString('base64')
.replace(/=*$/, '')
const now = Math.floor(new Date().getTime() / 1000)
const expiry = now + 3600
const payload = JSON.stringify({
aud: 'https://accounts.google.com/o/oauth2/token',
exp: expiry,
iat: now,
iss: serviceAccountEmail,
scope: scopes.join(' '),
sub: subject,
})
const header = JSON.stringify({
alg: 'RS256',
typ: 'JWT',
})
const iamPayload = `${unpaddedB64encode(header)}.${unpaddedB64encode(payload)}`
const iam = google.iam('v1')
const { data } = await iam.projects.serviceAccounts.signBlob({
auth: authClient,
name: `projects/-/serviceAccounts/${serviceAccountEmail}`,
requestBody: {
bytesToSign: unpaddedB64encode(iamPayload),
},
})
const assertion = `${iamPayload}.${data.signature!.replace(/=*$/, '')}`
const headers = { 'content-type': 'application/x-www-form-urlencoded' }
const body = querystring.encode({ assertion, grant_type: 'urn:ietf:params:oauth:grant-type:jwt-bearer' })
const response = await fetch('https://accounts.google.com/o/oauth2/token', { method: 'POST', headers, body }).then(r => r.json())
const newCredentials = new OAuth2Client()
newCredentials.setCredentials({ access_token: response.access_token })
return newCredentials
} else {
throw new Error('Unexpected authentication type')
}
}