Allow to set the opentracing forward header via ENV

doc/parameters.md

@@ -242,3 +242,31 @@ URI that includes your password and portal endpoint in the following format: `<s
 When `THREESCALE_PORTAL_ENDPOINT` environment variable is provided, the gateway will download the configuration from 3scale on initializing. The configuration includes all the settings provided on the Integration page of the API(s).
 
 It is **required** to provide either `THREESCALE_PORTAL_ENDPOINT` or `THREESCALE_CONFIG_FILE` (takes precedence) for the gateway to run successfully.
+
+
+### `OPENTRACING_TRACER`
+
+**Example** `jaeger`
+
+This environment variable controls which tracing library will be loaded, right now, there's only one opentracing tracer available, `jaeger`.
+
+If empty, opentracing support will be disabled.
+
+
+### `OPENTRACING_CONFIG`
+
+This environment variable is used to determine the config file for the opentracing tracer, if `OPENTRACING_TRACER` is not set, this variable will be ignored.
+
+Each tracer has a default configuration file:
+    * `jaeger`: `conf.d/opentracing/jaeger.example.json`
+
+You can choose to mount a different configuration than the provided by default by setting the file path using this variable.
+
+**Example**: `/tmp/jaeger/jaeger.json`
+
+### `OPENTRACING_HEADER_FORWARD`
+
+**Defaul** `uber-trace-id`
+
+This environment variable controls the HTTP header used for forwarding opentracing information, this HTTP header will be forwarded to upstream servers.
+

gateway/conf.d/apicast.conf

@@ -35,7 +35,17 @@ location = /___http_call {
   proxy_set_header User-Agent $user_agent;
   proxy_set_header X-3scale-OAuth2-Grant-Type $grant_type;
   proxy_set_header 3scale-options $options;
-  proxy_set_header uber-trace-id $http_uber_trace_id;
+
+  # Hack for having a valid openresty config and valid liquid templating
+  #{% if opentracing_forward_header == nil or opentracing_forward_header == empty %}
+  #   {% assign opentracing_forward_header = "uber-trace-id" %}
+  #{% endif %}
+  #{% if opentracing_tracer != nil or opentracing_forward_header != nil %}
+  #   {% capture proxy_set_header_opentracing %}
+  #{#} proxy_set_header {{opentracing_forward_header}} $http_{{ opentracing_forward_header | replace: "-","_" }};
+  #   {% endcapture %}
+  #   {{ proxy_set_header_opentracing | replace: "#{#}", "" }}
+  #{% endif %}
 
   rewrite_by_lua_block {
     require('resty.http_ng.backend.ngx'):resolver()

gateway/conf.d/opentracing/jaeger.conf.liquid

@@ -1,2 +1,7 @@
 opentracing on;
-opentracing_load_tracer libjaegertracing.so {{ opentracing_config | default:"conf.d/opentracing/jaeger.example.json"}};
+
+{% if opentracing_config == nil or opentracing_config == empty %}
+    {% assign opentracing_config = "conf.d/opentracing/jaeger.example.json" %}
+{% endif %}
+
+opentracing_load_tracer libjaegertracing.so {{ opentracing_config }};

gateway/src/apicast/cli/environment.lua

@@ -95,6 +95,9 @@ _M.default_environment = 'production'
 -- @tfield ?string proxy_ssl_certificate_key path to SSL certificate key
 -- @tfield ?string proxy_ssl_session_reuse whether SSL sessions can be reused
 -- @tfield ?string proxy_ssl_password_file path to a file with passphrases for the certificate keys
+-- @tfield ?string opentracing_tracer loads an opentracing tracer library, for example: jaeger
+-- @tfield ?string opentracing_config opentracing config file to load
+-- @tfield ?string opentracing_forward_header opentracing http header to forward upstream
 -- @tfield ?policy_chain policy_chain @{policy_chain} instance
 -- @tfield ?{string,...} nameservers list of nameservers
 -- @tfield ?string package.path path to load Lua files
@@ -103,13 +106,13 @@ _M.default_environment = 'production'
 
 _M.default_config = {
     ca_bundle = env_value_ref('SSL_CERT_FILE'),
-
     proxy_ssl_certificate = env_value_ref('APICAST_PROXY_HTTPS_CERTIFICATE'),
     proxy_ssl_certificate_key = env_value_ref('APICAST_PROXY_HTTPS_CERTIFICATE_KEY'),
     proxy_ssl_session_reuse = env_value_ref('APICAST_PROXY_HTTPS_SESSION_REUSE'),
     proxy_ssl_password_file = env_value_ref('APICAST_PROXY_HTTPS_PASSWORD_FILE'),
     opentracing_tracer = env_value_ref('OPENTRACING_TRACER'),
     opentracing_config = env_value_ref('OPENTRACING_CONFIG'),
+    opentracing_forward_header = env_value_ref('OPENTRACING_FORWARD_HEADER'),
     policy_chain = require('apicast.policy_chain').default(),
     nameservers = parse_nameservers(),
     worker_processes = cpus() or 'auto',