Thank you very much Maxim for the detailed reply.
I have been battling it out since then and have finally succeeded in setting up the export server (Docker) so that it exports a PDF on a production test. Unfortunately the output is plain text and I see varying export server log errors depending on the combination.
App: 'https://app.banana.com:443'
Export Server: 'https://export.banana.com:8082'
What combination of Gantt configuration do I need?
exportServer: 'https://export.banana.com:8082'
translateURLsToAbsolute: true (default, not a URL because I can't put any assets on the exportServer)
clientURL: ? (leave it, app with port, app without port, export server with port)
ERRORS
Just exportServer: 'Failed to load resource: net::ERR_FAILED', 'Access to font at ... from origin 'null' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource."
exportServer + clientURL 'https://app.banana.com:443': 'Failed to load resource: the server responded with a status of 401 (Unauthorized)'
exportServer + clientURL 'https://export.banana.com:8082': 'puppeteer_evaluation_script', 'Page 1/1 reports: Refused to apply inline style because it violates the following Content Security Policy directive: "default-src 'self'". Either the 'unsafe-inline' keyword, a hash..., or a nonce ('nonce-...') is required to enable inline execution. Note also that 'style-src' was not explicitly set, so 'default-src' is used as a fallback.'
I can't get clientURL to work so I've allowed wildcard cors origin for app and the export server's apache. Do I need to enable wildcard cors origin inside the Docker container? Where's the only place I actually need to allow CORS?