I am aware that this is a SAAS product but we need to provide an architecture diagram to a customer for their internal review purposes prior to setting it up.
I am currently looking at this link and wondering how relevant it is to Jira Service Management: https://confluence.atlassian.com/cloud/atlassian-cloud-architecture-973494795.html
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The same architecture applies good for most Atlassian Products. When they mention Jira the same is supposed to apply for Jira Software, Jira Service Management.
Please find the updated architecture here https://www.atlassian.com/trust/reliability/cloud-architecture-and-operational-practices