I created a function called getServiceMedplumClient for server-side auth. Before I call any api, I call this function for auth:

export async function getServiceMedplumClient(): Promise<MedplumClient> {
  const client = new MedplumClient({ baseUrl: getMedplumBaseUrl() });
  
  try {
    await client.startClientLogin(getServiceAccountId(), getServiceAccountSecret());
    return client;
  } catch (error) {
    console.error('❌ Service client authentication failed:', error);
    throw error;
  }
}

It turns out it works when I have a new ClientApplication. After a while, the

startClientLogin

call starts to fail and returns a

Unauthorized; Token expired

error every second API call. What's bizarre is that the first API call's auth always works. It looks like the

verifyTokens

call always fails the second time. After changing my code to the below to bypass

verifyTokens

, the issue is resolved.

export async function getServiceMedplumClient(): Promise<MedplumClient> {
const baseUrl = getMedplumBaseUrl();
  const clientId = getServiceAccountId();
  const clientSecret = getServiceAccountSecret();

  // try direct token
  const res = await fetch(`${baseUrl}/oauth2/token`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
    body: new URLSearchParams({
      grant_type: 'client_credentials',
      client_id: clientId,
      client_secret: clientSecret,
    }),
  });
  if (!res.ok) throw new Error(`Token request failed: ${res.status} ${await res.text()}`);
  const { access_token: accessToken } = await res.json();

  return new MedplumClient({ baseUrl, accessToken });
}

I don't understand why

startClientLogin

/`verifyTokens` fails the 2nd API call but works for the first call. Could anyone point me in the right direction? Thanks!

Nice, glad you got it sorted out!

For sure! @finnbergquist