Using Apache (httpd), demonstrate returning string literals and environment variables in response headers.

httpd-env-headers.conf

# Using Apache (httpd), demonstrate returning string literals and environment variables in response headers.
#
# Useful for simple containerized web service PoC.
#
# docker run -it --rm -p 80:80 -v "$(pwd)/httpd.conf":"/usr/local/apache2/conf/httpd.conf" httpd
#
# https://httpd.apache.org/docs/current/mod/mod_headers.html
# https://serverfault.com/questions/901459/apache-custom-header-with-an-environment-variable

# ... snip config file contents ....

Header Set X-String-Literal "foobar"

# Show the $HOSTNAME env var that is set by default in the httpd container.
PassEnv HOSTNAME
Header Set X-Env-Hostname %{HOSTNAME}e

# If a value was passed in from SSM Parameter Store.
PassEnv SSM_PARAMETER_VALUE
Header always set X-Env-SSM-Value "%{SSM_PARAMETER_VALUE}e"