Server configuration

nevisProxy server properties are configured via the four tags Service, Core, Timer, and Server. The Qos tag defines some frequently used attributes of Apache's quality of the service module mod_qos. By setting the Qos tag parameters, you enable a basic protection against denial of service (DoS) attacks. The Qos tag is optional.

Service

The attributes in the following table are only relevant for integration purposes and are mainly documented here as a reference. If nevisProxy is installed using the delivered package, none of these parameters need to be changed. The Service section does not contain any operation-relevant parameters (e.g., scaling).

Name	Type, Usage constraints, Defaults	Description
commandLine	string optional, advanced, supports variable replacement	The attribute 'commandLine' configures the command line arguments that will be used for starting the server. Example: commandLine="-X" starts the Apache server in debug mode. With the commandline argument NAVAJOgroup=<group-name> the group of the initial process can be configured. If configured, a 'setgid(..) call will be made. If an error occurs, an error message will be traced on 'stderr' but without terminating the process.
hostTemplate	string required, advanced, supports variable replacement, default:/opt/nevisproxy/etc/host2.template	The attribute 'hostTemplate' specifies the path to the template file used for creating the host part of the generated Apache configuration file (httpd.conf). It is not recommended to change this setting.
name	string optional, advanced, supports variable replacement default: isi3web	The attribute 'name' is a logical name. It is reserved for future use (e.g., running several services in one carrier server). This value should not be changed.
spoolDir	string required, advanced, supports variable replacement default: <spool_dir>	The path of the spooldir, i.e., the directory that contains the directory 'logs' for log files and 'run' for runtime data. This value should not be changed (must not be an NFS-mounted directory).
serverTemplate	string required, advanced, supports variable replacement default: /opt/nevisproxy/etc/server2.template	The attribute 'serverTemplate' specifies the path to the template file used to create the server part of the generated Apache 2 configuration file. Should not be changed. (Changing that file is a way of including additional Apache1/2 modules. However, that should not be necessary. Contact Nevis if you think you need additional modules.)
verbose	boolean: true, false optional, troubleshooting default: false	The attribute 'verbose' specifies server verbosity. If set to 'true', the message of all caught exceptions is sent to the client. Should be set to 'false' in production.
crashRecoveryStrategy	enum: recover, block, kill; default: recover	Specifies what should happen after a worker crash. By default, the child process is recovered by the parent process. This is the recommended strategy for classic deployments. If block is configured, after a worker crash every request will be blocked by 503 Service Unavailable status code. If kill is configured, the whole nevisproxy process (including the parent process) will be killed. This works only if the owner of the child process has the rights to kill the parent process (for example in some Kubernetes setups). If the parent cannot be killed, then the behaviour will be the same as block. The strategies block and kill are mainly designed for Kubernetes setups with an automated liveness monitoring, so the given pod can be terminated normally in case of a crash. If you set block or kill for a classic deployment, make sure to setup an automated procedure to restart nevisProxy after a crash. Note for testing: with the strategy block and kill, the blocking takes place only if at least one request is in processing when the crash occurs.

Core

The attributes in the following table are only relevant for integration purposes and are mainly documented here for reference. If nevisProxy is installed using the delivered package, none of these parameters needs to be changed. The Core section does not contain any operation-relevant parameters.

Deprecated

The runtime model and the memory type used (depending on whether Apache1 or Apache2 is used) in the Core configuration tag are deprecated.

Name	Type, Usage constraints, Default	Description
memoryProtection	boolean: true, false, optional, advanced, default: true	The attribute memoryProtection configures memory protection. After initialization and loading of all web applications, the container memory is write protected. This is possible only if memory type is set to ’shared’. Use of memory protection is recommended for the following reasons: The server can be restarted and current session context (authenticated users) is kept. Vendor code, that violates memory, is likely to not being able to corrupt nevisProxy runtime structures and user session context. Must not be changed.
memorySize	integer [bytes]required, advanced, supports variable replacement default: 10’000’000	The attribute memorySize specifies the amount of memory to be allocated. This memory is used to store the nevisProxy’s runtime structures. Memory requirements depend mainly on the size and number of the web applications to be loaded. The used memory, i.e. shared or heap, is configured in the Core element. (After booting the service, a log entry shows used and available memory. This information can be used for optimizing the configuration.) This parameter has to be increased if starting of nevisProxy failed due to out of memory errors. The default of 10 MB is about 10 times higher than a usual reverse proxy setup requires. See also "Appendix G - Sizing Parameters in the Nevis Proxy".
memoryType	enumeration: heap, sharedoptional, advanced, default: shared	The attribute memoryType is used to configure the memory model used. Can be changed for performance reasons.
memoryAnonomous	boolean, default: true	The attribute memoryAnonymous configures memory mapping. If set to ’false’, the shared memory will be mapped to a file <workDir>/shared_map_XXXXXX. Otherwise it will be mapped anonymously.
workDir	stringrequired, advanced, supports variable replacement, default: <spool_dir>/run	The attribute workDir configures the directory for the internal files. Should not be changed (may not be an NFS-mounted directory).

Timer

Timers are used to trigger asynchronous functions like the periodic check of the session cache for expired sessions.

Name	Type, Usage constraints, Default	Description
periodicity	integer [sec]optional, advanced, supports variable replacement, default: 60	The attribute periodicity configures the periodicity of the internal timer for releasing unused resources. A session with an absolute timeout of 2 hours would therefore have a real maximum lifetime of 2 hours and 60 seconds, in this case. Setting the value to a lower number, in turn, leads to more load.

OpenTelemetry

Experimental Service

The OpenTelemetry configuration tag integrates the OpenTelemetry standard to export observability data to a variety of open source and commercial backends.

This tag contains the tags Trace and Metrics.

Trace

The Trace configuration tag contains the values that are used to send tracing information to the OpenTelemetry service.

ExporterType

Type: Enum
Possible values: http
Default: http

Configures the protocol used for communicating with the traces endpoint.

ExporterAddress

Type: String
Usage Constraints: required if ExporterType is set to http
Syntax: <hostname>:<port>

Target URL to which the exporter sends spans. The /v1/traces path is automatically attached to it.

PropagateContextExtract

Type: Boolean
Usage Constraints: optional
Default: true

If present, extracts the trace context from the HTTP request header and sets it as parent for the current span.

PropagateContextInject

Type: Boolean
Usage Constraints: optional
Default: true

Injects the current context (span ID, trace ID, etc) as a HTTP header to the request.

ResourceServiceName

Type: String
Usage Constraints: optional
Default: nevisproxy

Allows the configuration of the service.name key-value pair resource attribute.

Metrics

The Metrics configuration tag contains the values that are used to send metrics information to the OpenTelemetry service.

ExporterType

Type: Enum
Usage Constraints: optional
Possible values: http
Default: http

Configures the protocol used for communicating with the metrics endpoint.

ExporterAddress

Type: String
Usage Constraints: required if ExporterType is set to http
Syntax: <hostname>:<port>

Target URL to which the exporter sends metrics like number of session or used memory etc. The /v1/metrics path is automatically attached to it.

Timeout

Type: Integer (milliseconds)
Usage Constraints: optional
Default: 30000

Length of time the export can run before it is cancelled. The default value is in milliseconds.

Interval

Type: Integer (seconds)
Usage Constraints: optional
Default: 60

Number of seconds for the telemetric's metric reader to initiate metric collection.

Trace example

A request trace contains the following extra attributes:

• http.url: Request URL
• http.scheme: HTTP request scheme
• http.method: HTTP request method
• http.client_ip: Client IP of the request
• http.nevisproxy.TransferID: the nevisProxy transfer ID of the given request
• http.header.*: list of request headers

A sample request trace:

Resource SchemaURL: 
Resource attributes:
     -> telemetry.sdk.version: Str(1.8.2)
     -> telemetry.sdk.name: Str(opentelemetry)
     -> telemetry.sdk.language: Str(cpp)
     -> service.version: Str(5.8.0)
     -> host.name: Str(localhost.localdomain)
     -> service.name: Str(myService)
ScopeSpans #0
ScopeSpans SchemaURL: 
InstrumentationScope nevisproxy 
Span #0
    Trace ID       : b431f642dbc6dd90aceecfc0d5e578ce
    Parent ID      : 
    ID             : 896e844078bc04fe
    Name           : /test/
    Kind           : Server
    Start time     : 2023-10-24 14:21:44.64604676 +0000 UTC
    End time       : 2023-10-24 14:21:44.662755045 +0000 UTC
    Status code    : Unset
    Status message : 
Attributes:
     -> http.url: Str(http://localhost/test/)
     -> http.scheme: Str(http)
     -> http.method: Str(GET)
     -> http.client_ip: Str(127.0.0.1)
     -> http.nevisproxy.TransferID: Str(002d71-16981573046396495-18b62101b40)
     -> http.header.Connection: Str(keep-alive)
     -> http.header.Accept-Language: Str(en-US,en;q=0.5)
     -> http.header.Exporter: Str(http)
     -> http.header.TransferId: Str(16981573046396495)
     -> http.header.User-Agent: Str(htt)
    {"kind": "exporter", "data_type": "traces", "name": "logging"}

Metrics example

Currently only the session store servlets provide metrics about usage (number of active users, timed out sessions, etc). An example metrics provided by the LocalSessionStoreServlet:

Resource SchemaURL: 
Resource attributes:
     -> service.name: Str(unknown_service)
     -> telemetry.sdk.version: Str(1.8.2)
     -> telemetry.sdk.name: Str(opentelemetry)
     -> telemetry.sdk.language: Str(cpp)
ScopeMetrics #0
ScopeMetrics SchemaURL: 
InstrumentationScope LocalSessionStoreServlet 
Metric #0
Descriptor:
     -> Name: nevisproxy.db.local.memory.available
     -> Description: 
     -> Unit: Bytes
     -> DataType: Sum
     -> IsMonotonic: true
     -> AggregationTemporality: Cumulative
NumberDataPoints #0
StartTimestamp: 2023-10-24 20:27:13.679673511 +0000 UTC
Timestamp: 2023-10-24 20:27:14.680314798 +0000 UTC
Value: 92000
Metric #1
Descriptor:
     -> Name: nevisproxy.db.local.memory.used
     -> Description: 
     -> Unit: Bytes
     -> DataType: Sum
     -> IsMonotonic: true
     -> AggregationTemporality: Cumulative
NumberDataPoints #0
StartTimestamp: 2023-10-24 20:27:13.679673511 +0000 UTC
Timestamp: 2023-10-24 20:27:14.680314798 +0000 UTC
Value: 1464
Metric #2
Descriptor:
     -> Name: nevisproxy.db.local.timed_out
     -> Description: 
     -> Unit: 
     -> DataType: Sum
     -> IsMonotonic: true
     -> AggregationTemporality: Cumulative
NumberDataPoints #0
StartTimestamp: 2023-10-24 20:27:13.679673511 +0000 UTC
Timestamp: 2023-10-24 20:27:14.680314798 +0000 UTC
Value: 0
Metric #3
Descriptor:
     -> Name: nevisproxy.db.local.used
     -> Description: 
     -> Unit: 
     -> DataType: Sum
     -> IsMonotonic: true
     -> AggregationTemporality: Cumulative
NumberDataPoints #0
StartTimestamp: 2023-10-24 20:27:13.679673511 +0000 UTC
Timestamp: 2023-10-24 20:27:14.680314798 +0000 UTC
Value: 0

Server

The Server configuration tag contains the values that are used for the server part of the generated Apache configuration. The next table describes the relevant attributes. Note that all these attributes support variable replacement.

All listed parameters are directives of the Apache carrier server. They are documented in the corresponding Apache documentation: official Apache documentation.

Name	Type, Usage constraints, Default	Description
DocumentRoot	string required, advanced default: @PKG_VAR@/@PKG_INSTANCE@/htdocs	Deprecated The DocumentRoot parameter is deprecated. The attribute DocumentRoot configures the document directory for the Apache web server. It can be accessed from outside with a browser, the directory should therefore be empty. Should not be changed.
User	string required, advanced default: @PROXY_RT_USER@	The attribute User configures the owner of the running nevisProxy process. Should not be changed, as changes may lead to permission problems. If you set this attribute yourself, make sure that the ownership of the configuration, log files, and access to the binaries are set accordingly.
Group	string required, advanced default: @PROXY_RT_GROUP@	The attribute Group configures the process group of the current nevisProxy process. Should not be changed, as changes may lead to permission problems. If you set this attribute yourself, make sure that the ownership of the configuration, log files, and access to the binaries are set accordingly.
KeepAlive	enum: on, off optional, advanced default: on	The attribute KeepAlive configures the HTTP keepalive behavior of the frontend connectors of nevisProxy. If set to "on", it enables HTTP persistent connections. The thread or process remains bound to the client and cannot be used by others during the time period defined by the attribute KeepAliveTimeout.
KeepAliveTimeout	integer [seconds] optional scaling, advanced default: 5	Defines the number of seconds Apache HTTPD will wait for a subsequent request before closing the connection. By adding the postfix ms the timeout can be also set in milliseconds.
MaxKeepAliveRequests	integer optional, scaling default: 100	The attribute MaxKeepAliveRequests limits the number of requests allowed per connection when the attribute KeepAlive is "on". If it is set to "0", an unlimited number of requests is allowed. It is recommended setting a high value for maximum server performance.
MaxClients	integer optional, scaling default: 600	MaxClients is the old name for the attribute MaxRequestWorkers. The attribute limits the number of simultaneous requests that will be served.
MaxRequestsPerChild	integer optional, advanced default: 0 (unlimited)	MaxRequestsPerChild is the old name for the MaxConnectionsPerChild attribute. It limits the number of connections that an individual child server process will handle. After MaxRequestsPerChild connections, the child process will die. If the value of the attribute is "0", the process will never expire. Should not be changed.
Timeout	integer [sec] optional, scaling default: 30	Amount of time the server will wait for certain events before failing a request.
LimitRequestLine	integer [byte] optional, security default: 5120	Limits the size of the HTTP request line that will be accepted from the client.
LimitRequestBody	integer [byte] optional, scaling default: 512000	The attribute specifies the number of bytes that are allowed in a request body. It restricts the total size of the HTTP request body sent from the client. Allowed are integers from "0" (meaning unlimited) to "2147483647" (2GB).
LimitRequestFields	integer [byte] optional, security default: 50	Limits the number of HTTP request header fields that will be accepted from the client. Allowed are integers from "0" (meaning unlimited) to "32767".
LimitRequestFieldsize	integer [byte] optional, security default: 5120	Limits the size of the HTTP request header allowed from the client.
LimitRequestParameters	integer optional, security default: 10’000	The maximum number of parameters allowed in a request.
Loglevel	enum optional, troubleshooting, default: notice	The Loglevel attribute adjusts the verbosity of the messages recorded in the error logs (see the ErrorLog attribute). The directive Loglevel can be used to configure per-module log levels. Specifying a level without a module name will reset the level for all modules to that level. Specifying a level with a module name will set the level for that module only. An example configuration to configure the removed SSLLogLevel directive might look like this: Loglevel="info ssl:debug". For the available options, see the official Apache documentation.
ErrorLog	string required, advanced default: "&quot;\|@PKG_HOME@/bin/bclogmgr size=1000000 archives=10 @PKG_VAR@/@PKG_INSTANCE@/logs/apache.log&quot;"	Location where the server will log errors ("apache.log" by default). In the pkg default configuration, the file rotation of the error log is enabled using the bclogmgr. Note: The character ” must be escaped in XML using &quot;. Notes about configuring a custom location: The directory containing the logs must exist when starting the instance. The nevisProxy user must be able to read and write in this directory. See its username and group in the <Server> element of the navajo.xml file.
TransferLog	string optional, basic feature, default: "&quot;\|@PKG_HOME@/bin/bclogmgr size=10000000 archives=10 @PKG_VAR@/@PKG_INSTANCE@/logs/access.log&quot;"	Specifies the location of the access log file. In the pkg default configuration, the file rotation of the error log is enabled using the bclogmgr. Note: The character ” must be escaped in XML using &quot;. Notes about configuring a custom location: The directory containing the logs must exist when starting the instance. The nevisProxy user must be able to read and write in this directory. See its username and group in the <Server> element of the navajo.xml file. See also Enabling the Apache transfer log.
CustomLog	string optional, advanced feature, default: "&quot;\|@PKG_HOME@/bin/qslog -f ISBDUkEa -x -u @PROXY_RT_USER@ -o @PKG_VAR@/@PKG_INSTANCE@/logs/stat.log&quot; &quot;%h %>s %b %D %{clID}e %k %{Event}e %{dTr1B}e&quot;"	Configures an additional log facility. Note: The character ” must be escaped in XML using &quot;. Notes about configuring a custom location: The directory containing the logs must exist when starting the instance. The nevisProxy user must be able to read and write in this directory. See its username and group in the <Server> element of the navajo.xml file. See also Using the Apache CustomLog.
LogFormat	string optional, advanced default: "&quot;%h %l %u %t \&quot;%r\&quot; %>s %b %{content-length}i %T \&quot;%{Referer}i\&quot; \&quot;%{User-Agent}i\&quot; trID=%{UNIQUE_ID}e&quot;"	This attribute specifies the format of the access log file. Note: The character ” must be escaped in XML using &quot;
ServerAdmin	string required, advanced default: [email protected]	Deprecated This attribute is deprecated. The attribute ‘ServerAdmin’ configures the mail address of the server administrator and should be changed after installation. As the default Apache error page should never be displayed, this attribute is not really relevant.
ServerName	string required, basic connectivity default: DNS name of the machine	The attribute ServerName sets the request scheme, hostname and port that the server uses to identify itself. Syntax: `[scheme://]domain-name
ServerRoot	string required, advanced default: @PKG_VAR@/@PKG_INSTANCE@	The attribute ServerRoot configures the root directory of the Apache web server. Should not be changed.
ServerSignature	enum: On, Off, EMail optional default: Off	Configures the Apache directive "ServerSignature". Usually this should not be changed.
ServerTokens	enum: Major|Minor|Min[imal]|Prod[uctOnly]|OS|Full optional, advanced default: Prod	This attribute controls whether the Server response header field, which is sent back to clients, includes a description of the generic OS-type of the server as well as information about compiled-in modules. Possible values: ServerTokens Full: Server sends (e.g.): Server: Apache/2.4.2 (Unix) PHP/4.2.2 MyMod/1.2 ServerTokens Prod[uctOnly]: Server sends (e.g.): Server: Apache ServerTokens Major: Server sends (e.g.): Server: Apache/2 ServerTokens Minor: Server sends (e.g.): Server: Apache/2.4 ServerTokens Min[imal]: Server sends (e.g.): Server: Apache/2.4.2 ServerTokens OS: Server sends (e.g.): Server: Apache/2.4.2 (Unix) This setting applies to the entire server. It cannot be enabled or disabled on a virtualhost-by-virtualhost basis.
Include	string optional, advanced default: not set	Use this attribute to include any additional Apache configuration fragment.
CoreDumpDirectory	string optional, troubleshooting default: not set	The attribute CoreDumpDirectory configures the directory to which the Apache web server writes core files.
UseCanonicalName	enum: On, Off, DNS optional, troubleshooting default: On	Configures how the server determines its own name and port. For more information, see the official Apache documentation.
ThreadStackSize	integer optional, scaling default: 1048576	Defines the size in bytes of the stack used by threads handling client connection. See also Appendix G - Sizing Parameters in the Nevis Proxy.
HttpProtocolOptions	string optional, advanced default: not set	Modifies restrictions on HTTP Request Messages.Syntax: `[Strict
SSLPassPhraseDialog	string optional, advanced default: ‘builtin’	The attribute SSLPassPhraseDialog configures the passphrase retriever used by mod_ssl. Only the "builtin" option is supported. For information on how the passwords for password protected keys are fetched, see the description of the bc-properties bc.security.PassPhrasePolicy and bc.security.PassPhraseDialog in the chapter Low-level properties.
SSLSessionCacheTimeout	integer optional default: 300	Defines the number of seconds before an SSL session expires in the Session Cache. This directive sets the timeout in seconds for the information stored in the global/inter-process SSL Session Cache, the OpenSSL internal memory cache and for sessions resumed by TLS session resumption (RFC 5077). It can be set as low as 15 for testing, but should be set to higher values like 300 in real life. If you use an own SSLCache or RemoteSSLCache, the system ignores the SSLSessionCacheTimeout parameter.
SSLSessionCache	string , optional , default: shmcb:@PKG_VAR@/@PKG_INSTANCE@/run/apache_shmcb"	This attribute defines the TLS session cache. The following value options are available: "None" This setting disables the global/inter-process TLS session cache. It will incur a noticeable speed penalty and may cause problems if using certain browsers, particularly if client certificates are enabled. We do not recommend this setting. "Nonenotnull" This setting disables any global/inter-process TLS session cache. However, the setting does force OpenSSL to send a non-null session ID, to accommodate buggy clients that require one. "shmcb:/path/to/datafile[(size) This setting makes use of a high-performance cyclic buffer (approx. (size) bytes in size) inside a shared memory segment in RAM (established via/path/to/datafile*), to synchronize the local OpenSSL memory caches of the server processes. The default parameter of SSLSessionCache refers to the generated xml’s content. Removing the parameter sets the SSLSessionCache to none.