HTTP_RESPONSE - STREAM::expression to replace one string with another in HTTP data payload

Everything is working after adding a custom httpcompression profile to the LTM virtual server and specifying content-types for compression. I also had to tell the server to remove Accept-Encoding in the HTTP request block of the iRule, because if the server's HTTP response comes back to f5 compressed then stream cannot parse for the string we want to replace. The httpcompression profile is to compress the HTTP response before f5 sends it back to the original client.

Final iRule looks like this:

# If URI starts with /fooportal 

# then reverse proxy to foo.example.com

# If the URL started with anything other than /fooportal

# then 307 redirect to foo.example.com 

# but with the originally requested path

#

# https://clouddocs.f5.com/api/irules/STREAM.html

# https://support.f5.com/csp/article/K39394712

# https://clouddocs.f5.com/api/irules/STREAM__expression.html

# https://devcentral.f5.com/s/question/0D51T00006i7fhv/understanding-stream-expression-and-compression

# https://clouddocs.f5.com/cli/tmsh-reference/latest/modules/ltm/ltm_profile_stream.html

# https://support.f5.com/csp/article/K15434

# https://techdocs.f5.com/en-us/bigip-14-0-0/big-ip-local-traffic-manager-implementations-14-0-0/compressing-http-responses.html

#

when HTTP_REQUEST {

 # Disable the stream filter for client requests

 STREAM::disable

 if { ([string tolower [HTTP::uri]] starts_with "/fooportal") } {

   HTTP::header replace Host "foo.example.com"

   # Tell server not to compress response

    # LTM does not uncompress response content, so if the webserver has compression enabled

    # we must prevent the server from sending us a compressed response by changing the request

    # header that indicates client support for compression (on our LTM client-side we can re-

    # apply compression before the response goes across the Internet)

   HTTP::header remove Accept-Encoding

   pool foo.example.com_HTTPS_Pool

 } elseif { ([string tolower [HTTP::header host]] eq "app.foo.example.com") } { 

   HTTP::header replace Host "foo.example.com"

HTTP::respond 307 Location https://[HTTP::host][HTTP::uri]

 }

}

when HTTP_RESPONSE {

 # Disable the stream filter for server responses

 STREAM::disable

 # Enable the stream filter for text responses only

 if {([HTTP::status] == 200) && ([HTTP::header value Content-Type] starts_with "text")} {

  # Replace 'foo' with 'app.foo'

  STREAM::expression {@foo.example.com/fooportal@app.foo.example.com/fooportal@}

  # Enable the stream filter

  STREAM::enable

  # enable compression

  COMPRESS::enable

 }

}