NGP7 - Wazimap profile domain management
Proposed by: JD Bothma
Date: April 2022
Status: Spike probable solution
Context
As wazimap scales in the number of profiles it hosts, we will need to serve on more and more hostnames. Each hostname we serve has to be valid for the TLS certificate, and traffic for that hostname has to be routed to the Wazimap NG frontend. That imposes the following requirements for adding a new profile:
Come up with an appropriate hostname
currently: usually a geo. prefix to the client's domain
also: a sandbox-geo. prefix for a second profile to use as sandbox
often: initially just a projectname.wazimap.openup.org.za subdomain to get things moving quickly
Relate the hostname to the relevant profile in Wazimap admin
A Profile Admin level user can do this. It's currently JSON but can be made simpler.
Configure the frontend web server to serve that hostname
currently: add it as a custom domain in netlify
Provision a new TLS certificate which includes the new domain as a Subject Alternate Name
currently: Click renew certificate, then verify DNS, then renew certificate, perhaps a number of times, until it's happy - in netlify
Problems with this approach:
A networking-aware developer has to do the DNS and custom domain configuration
Stale domains can break certificate renewal
Netlify has a limit to the number of custom domains allowed - they have warned us not to add more than 100
The Certificate is growing bigger and bigger. We aren't sure of the consequences of this.
Anticipated scale over the next 1-3 years:
We are aiming for 40 profile subscriptions by the end of 2022-2023 financial year.
Pending: Feedback from current profile owners on the importance of custom domains for their profiles.
Based on the current profiles, we guess that at least 50% would consider custom domains important.
Certificates per Registered Domain (50 per week) - Only really relevant if we try to have a distinct certificate per wazimap.co.za subdomain instead of a wildcard certificate for that domain. Renewal could be staggered. This would probably happen naturally by renewing daily a month before expiry as is currently done.
Names per Certificate (100) - Relevant if all domains are on a single certificate. This (all domains added as Subject Alternative Name values on a single certificate for the app) is the usual approach dokku-letsencrypt and netlify uses for domains added to the same app.
Failed Validation limit of 5 failures per account, per hostname, per hour. - Relevant if one certificate is used for multiple domains, and DNS for one of the domains is not resolving to us yet. We'd need to be careful about accidental or intentional denial of service here.
Limits on Netlify:
Wildcard domains are supported on Pro, but not at the same time as custom domains
TLS Certificates can only be handled by Netlify if Netlify DNS is used for the wildcard cart
Only 100 custom domains are supported on a site. (Possibly due to letsencrypt Names per Cert limit)
Client wants/needs
Youth explorer very much is an established brand in their circles.
Could you please also let us know what the technical costs are for keeping a custom domain.
whowhatwhere.org.za
Similar functionality on competitors/related tools
Power BI
Carto
Tableau
Proposed Solution 1 - Only allow subdomains of our base domain
Requirements:
Once-off wildcard DNS for the base domain, e.g. *.wazimap.co.za
Supported by netlify, dokku
2-monthly wildcard TLS certificate for the wildcard domain
Supported by netlify, dokku
Wildcard reverse proxying to the frontend web server
Supported by netlify, dokku
Benefits
Disadvantages
Proposed Solution 2 - Allow subdomain of our base domain for new sites, and legacy custom domains
Requirements:
Same as solution 1 for wildcard DNS/cert/proxying
The solution 1 requirements for about 5 custom domains
Supported by dokku
Benefits
Disadvantages
Other implications
Proposed Solution 3 - subdomains by default, option of custom domains on dokku added manually
Approach
DNS
Wildcard DNS for subdomains of our base domain
Any DNS CNAME to to our frontend web server
Virtual hosting (reverse proxy or static server)
Subdomains are handled automatically by dokku/nginx wicard domain
Custom domains: ??? manually-added or automated?
TLS certificate
alternative to dokku letsencrypt: certbot + vhost per custom domain + dokku app listening on a host port for non-dokku reverse proxy
Adding/removing a domain manually would entail
Add the domain to the profile in Admin
Add CNAME record pointing to the server, or ask the client to do so
SSH to the server
Add domain to dokku/nginx vhost
Renew TLS certificate
For 20 custom domains, we might have to do this on average 30 times or just over once every 2 weeks.
Beware cert renewal errors.
Can one hostname break renewal for all or is that one skipped?
We can monitor expiry.
We can monitor the renewal cron output.
-> Urgent manual devops action until we automate.
Benefits
Disadvantages
Proposed Solution 4 - subdomains by default, option of custom domains on dokku automated
Same as Solution 3 but instead of adding/removing domains manually by SSHing to the server, we automate that, triggered by domain modifications in admin.
Approach:
Add the domain to the profile in Admin
Add CNAME record pointing to the server, or ask the client to do so
...Automation to add/remove domain config to server
...Automation to renew certificate
...Automation to let admin know it's all up and running or feed back errors
Benefits
Disadvantages
Proposed Solution 5
Benefits
Disadvantages
Resolution
Try option 3 until the effort of maintaining custom domains manually and the value to be gained by automating is worth the effort of automating handling custom domains.
Further reading
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