docs/srh.md

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+# SRH
+
+## URL Rewrite Setup for MyChart Provider Finder 
+
+SRH wants to use a vanity URL for a third party hosted application which only presented IIS xml configuration documentation so I'm translating it here for transparency. I've included Claude.ai and Github Copilot translations from the original 👉🏻 📄 [documentation](https://davidawindham.com/wha/srh_rewrites.pdf)
+
+## Variables
+
+- CustomDomain: https://providers.selfregional.org
+- CustomProviderFinder: providers
+- CustomHostID: MySelfRegional
+- MyChartDomain: https://mychart-np.et1235.epichosted.com/MySRHTST/
+- MyChartSiteName: MySRHTST
+
+## IIS Rules
+
+```html
+<rule name="Provider Finder Example" enabled="true" patternSyntax="Wildcard" stopProcessing="true">
+  <match url="providers*" />
+  <conditions logicalGrouping="MatchAll" trackAllCaptures="false" />
+  <action type="Rewrite" url="https://mychart-np.et1235.epichosted.com/MySRHTST/-/providers{R:1}?host=MySelfRegional" />
+</rule>
+
+<rule name="Vanity MyChart Redirect Example" enabled="true" patternSyntax="Wildcard" stopProcessing="true">
+  <match url="MySelfRegional/*" />
+    <conditions>
+      <add input="{HTTP_ACCEPT}" pattern="*text/html*" />
+    </conditions>
+  <action type="Redirect" url="https://mychart-np.et1235.epichosted.com/MySRHTST/{R:1}" redirectType="Found" />
+</rule>
+
+<rule name="Assets Example" enabled="true" patternSyntax="Wildcard" stopProcessing="true">
+  <match url="MySelfRegional/*" />
+  <conditions logicalGrouping="MatchAll" trackAllCaptures="false" />
+  <action type="Rewrite" url="https://mychart-np.et1235.epichosted.com/MySRHTST/{R:1}" />
+</rule>
+
+<rule name="MyChart Redirect Example" patternSyntax="Wildcard" stopProcessing="true">
+  <match url=" MySelfRegional/*" />
+    <conditions>
+      <add input="{HTTP_ACCEPT}" pattern="*text/html*" />
+    </conditions>
+  <action type="Redirect" url=" https://mychart-np.et1235.epichosted.com/MySRHTST/{R:1} " />
+</rule>
+
+<rule name="Hosted Provider Finder Example" preCondition="Hosted Provider Finder Precondition" enabled="true" patternSyntax="Wildcard">
+  <match filterByTags="Area, Base, Form, Frame, Head, IFrame, Img, Input, Link, Script, CustomTags" customTags="Hosted Provider Finder Collection" pattern="/MySRHTST/*" negate="false" />
+  <action type="Rewrite" value="/MySelfRegional/{R:1}" />
+</rule>
+
+<preCondition name="Hosted Provider Finder Precondition">
+  <add input="{REQUEST_URI}" pattern="/-/providers" />
+  <add input="{QUERY_STRING}" pattern="host=" />
+</preCondition>
+<customTags>
+  <tags name="Hosted Provider Finder Collection">
+      <tag name="meta" attribute="content" />
+      <tag name="use" attribute="xlink:href" />
+  </tags>
+</customTags>
+
+<rule name="Provider Finder Canonical URL Rewrite Example" preCondition="Provider Finder Canonical URL Precondition">
+  <match filterByTags="Link" pattern="^https?:\/\/[^ ]*(app\/providers|\/-\/providers)([^ ]*)/" />
+  <action type="Rewrite" value="https://providers.selfregional.org/providers {R:2}" />
+ </rule>
+
+<preCondition name="Provider Finder Canonical URL Precondition" logicalGrouping="MatchAny">
+  <add input="{REQUEST_URI}" pattern="(\/app\/providers|\/-\/providers)" />
+  <add input="{QUERY_STRING}" pattern="host=" />
+</preCondition>
+```
+
+
+---
+
+### CoPilot Translation
+
+```sh
+# Provider Finder Example
+    location ~ ^/providers(.*)$ {
+        rewrite ^/providers(.*)$ https://mychart-np.et1235.epichosted.com/MySRHTST/-/providers$1?host=MySelfRegional break;
+    }
+    
+    # Vanity MyChart Redirect Example
+    location ~ ^/MySelfRegional/(.*)$ {
+        if ($http_accept ~* "text/html") {
+            return 302 https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+        }
+        # Assets Example (if not text/html)
+        proxy_pass https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+    }
+    
+    # MyChart Redirect Example
+    location ~ ^/\ MySelfRegional/(.*)$ {
+        if ($http_accept ~* "text/html") {
+            return 302 https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+        }
+    }
+    
+    # Hosted Provider Finder Example
+    # Note: This rule is complex and might need custom Nginx modules for HTML parsing
+    # The following is a simplified approximation
+    location ~ ^/-/providers {
+        if ($args ~* "host=") {
+            sub_filter "/MySRHTST/" "/MySelfRegional/";
+            sub_filter_once off;
+        }
+    }
+    
+    # Provider Finder Canonical URL Rewrite
+    # Note: This requires more complex HTML parsing that's not standard in Nginx
+    # Consider using a JavaScript solution or Nginx with Lua module
+    location ~ ^/(app/providers|/-/providers) {
+        set $do_rewrite 0;
+        
+        if ($uri ~* "(\/app\/providers|\/-\/providers)") {
+            set $do_rewrite 1;
+        }
+        
+        if ($args ~* "host=") {
+            set $do_rewrite 1;
+        }
+        
+        if ($do_rewrite = 1) {
+            # Would need ngx_http_subs_filter_module or Lua for HTML tag manipulation
+            # This is a placeholder - actual implementation requires more advanced modules
+            rewrite ^.*(app\/providers|\/-\/providers)(.*)$ https://providers.selfregional.org/providers$2 break;
+        }
+    }
+```
+
+---
+
+### Claude Translation 
+
+#### Nginx configuration equivalent to IIS rules
+
+```sh
+server {
+    listen 80;
+    server_name your-domain.com;
+
+    # Rule 1: Provider Finder Example
+    # IIS: providers* -> rewrite to external URL with query param
+    location ~* ^/providers(.*)$ {
+        rewrite ^/providers(.*)$ https://mychart-np.et1235.epichosted.com/MySRHTST/-/providers$1?host=MySelfRegional last;
+    }
+
+    # Rule 2: Vanity MyChart Redirect Example  
+    # IIS: MySelfRegional/* with HTML accept header -> redirect
+    location ~* ^/MySelfRegional/(.*)$ {
+        if ($http_accept ~* "text/html") {
+            return 302 https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+        }
+        # If not HTML request, fall through to Rule 3 (Assets Example)
+        rewrite ^/MySelfRegional/(.*)$ https://mychart-np.et1235.epichosted.com/MySRHTST/$1 last;
+    }
+
+    # Rule 4: MyChart Redirect Example (with spaces - appears to be duplicate/typo)
+    # This seems to be a duplicate of Rule 2 with extra spaces, handling it as fallback
+    location ~* ^/\s*MySelfRegional/(.*)$ {
+        if ($http_accept ~* "text/html") {
+            return 302 https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+        }
+    }
+
+    # Provider Finder with host parameter handling
+    location ~* ^/-/providers {
+        if ($args ~* "host=") {
+            # This handles the precondition logic for provider finder
+            rewrite ^/-/providers(.*)$ /MySelfRegional/$1 last;
+        }
+    }
+
+    # Provider Finder Canonical URL handling
+    # This is more complex in Nginx as it involves response body modification
+    # You would typically use nginx's sub_filter module for this:
+    location ~* ^/(app/providers|/-/providers) {
+        if ($args ~* "host=") {
+            # Enable response body modification
+            sub_filter_once off;
+            sub_filter_types text/html text/css text/xml application/javascript;
+            sub_filter 'https://[^ ]*(app/providers|/-/providers)([^ ]*)/' 'https://providers.selfregional.org/providers$2';
+        }
+        # Continue processing the request normally
+        try_files $uri $uri/ =404;
+    }
+}
+```
+
+### Additional configuration notes:
+
+1. The IIS "Hosted Provider Finder" rule with filterByTags is complex
+   In Nginx, you'd need to use the sub_filter module or a Lua script
+   to modify response content based on HTML tags
+2. For response body modification (Rules 5-7), you may need:
+   - nginx sub_filter module (basic text replacement)
+   - nginx-lua module (for complex logic)
+   - Or handle this at the application level
+3. Make sure to enable these modules if needed:
+   load_module modules/ngx_http_sub_filter_module.so;
+4. The stopProcessing="true" behavior is handled by using 'last' flag
+   in rewrite rules and proper location block ordering
+
+
+Here are the key differences and considerations when translating from IIS to Nginx:
+Important Notes:
+
+1. Rule Processing Order: Nginx processes location blocks in a specific order (exact match → longest prefix → regex). The IIS stopProcessing="true" is handled by the last flag in rewrites.
+
+2. Wildcard vs Regex: IIS uses wildcard patterns (*), while Nginx uses regex. I've converted providers* to ^/providers(.*)$.
+
+3. Complex Response Modification: Rules 5-7 in your IIS config involve modifying response content based on HTML tags. This requires additional Nginx modules:
+- sub_filter module for basic text replacement
+- nginx-lua module for complex logic
+- Or handle at the application level
+
+4. Conditional Logic: IIS conditions become Nginx if statements, though Nginx's if is generally discouraged except for simple cases like checking headers.
+
+5. External Rewrites: Your rules rewrite to external URLs, which Nginx handles well with the rewrite directive.
+
+
+---
+
+## CURRENT CONFIG
+
+**note** the ```underscores_in_header``` directive is required and the ```sub_filter``` module is not available in the current nginx build. 
+
+```sh
+underscores_in_headers on;
+
+location / {
+  rewrite ^/(.*)$ /MySRHTST/-/providers/$1?host=MySelfRegional break;
+  proxy_set_header Host $host;
+  proxy_set_header X-Real-IP $remote_addr;
+  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+  proxy_set_header X-Forwarded-Proto $scheme;
+  proxy_set_header RequestVerificationToken $http_requestverificationtoken;
+  proxy_pass https://mychart-np.et1235.epichosted.com;
+}
+
+# Vanity MyChart Redirect Example
+location ~ ^/MySelfRegional/(.*)$ {
+  # Assets Example (if not text/html)
+  proxy_set_header Host $host;
+  proxy_set_header X-Real-IP $remote_addr;
+  proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+  proxy_set_header X-Forwarded-Proto $scheme;
+  proxy_set_header RequestVerificationToken $http_requestverificationtoken;
+  proxy_pass https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+}
+
+# MyChart Redirect Example
+location ~ ^/\ MySelfRegional/(.*)$ {
+  if ($http_accept ~* "text/html") {
+    return 302 https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+  }
+}
+
+# Hosted Provider Finder Example
+location ~ ^/-/providers {
+  if ($args ~* "host=") {
+    # Implementation needed
+  }
+}
+
+# Canonical URL Rewrite (modified to not use providers)
+location ~ ^/(app/providers|/-/providers) {
+  set $do_rewrite 0;
+  if ($uri ~* "(\/app\/providers|\/-\/providers)") {
+    set $do_rewrite 1;
+  }
+  if ($args ~* "host=") {
+    set $do_rewrite 1;
+  }
+  if ($do_rewrite = 1) {
+    # Modified to use domain root instead of /providers
+    rewrite ^.*(app\/providers|\/-\/providers)(.*)$ https://providers.selfregional.org$2 break;
+  }
+}
+```
+
+this was the original test run under the ```/providers``` subdirectory
+
+
+```sh
+underscores_in_headers on;
+
+# Provider Finder Example
+location ~ ^/providers(.*)$ {
+	rewrite ^/providers(.*)$ /MySRHTST/-/providers$1?host=MySelfRegional break;
+	proxy_set_header Host $host;
+	proxy_set_header X-Real-IP $remote_addr;
+	proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+	proxy_set_header X-Forwarded-Proto $scheme;
+	proxy_set_header RequestVerificationToken $http_requestverificationtoken;
+	proxy_pass https://mychart-np.et1235.epichosted.com;
+}
+
+# Vanity MyChart Redirect Example
+location ~ ^/MySelfRegional/(.*)$ {
+
+	# Assets Example (if not text/html)
+	proxy_set_header Host $host;
+	proxy_set_header X-Real-IP $remote_addr;
+	proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+	proxy_set_header X-Forwarded-Proto $scheme;
+	proxy_set_header RequestVerificationToken $http_requestverificationtoken;
+	proxy_pass https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+}
+
+# MyChart Redirect Example
+location ~ ^/\ MySelfRegional/(.*)$ {
+	if ($http_accept ~* "text/html") {
+		return 302 https://mychart-np.et1235.epichosted.com/MySRHTST/$1;
+	}
+}
+
+# Hosted Provider Finder Example
+# Note: This rule is complex and might need custom Nginx modules for HTML parsing
+# The following is a simplified approximation
+location ~ ^/-/providers {
+	if ($args ~* "host=") {
+
+	}
+}
+
+# Provider Finder Canonical URL Rewrite
+# Note: This requires more complex HTML parsing that's not standard in Nginx
+# Consider using a JavaScript solution or Nginx with Lua module
+location ~ ^/(app/providers|/-/providers) {
+	set $do_rewrite 0;
+
+	if ($uri ~* "(\/app\/providers|\/-\/providers)") {
+		set $do_rewrite 1;
+	}
+
+	if ($args ~* "host=") {
+		set $do_rewrite 1;
+	}
+
+	if ($do_rewrite = 1) {
+		# Would need ngx_http_subs_filter_module or Lua for HTML tag manipulation
+		# This is a placeholder - actual implementation requires more advanced modules
+		rewrite ^.*(app\/providers|\/-\/providers)(.*)$ https://providers.selfregional.org/providers$2 break;
+	}
+}
+```