AppSwitch Command Line Options¶
AppSwitch features are provided through the
This guide goes over various options supported by
ax command thereby
describing the related features. The top level commands include:
daemon Start the AppSwitch daemon run Run an application under AppSwitch get Get active resources create Create a resource delete, del Delete a resource
daemon sub command is used to start the AppSwitch daemon.
System Call Forwarding Driver¶
--driver name System call forwarding driver name ('user' or 'kernel')
AppSwitch can be used with either a user-space driver or a kernel-space driver. If the –driver flag is not set then the default behavior is to use the kernel driver if the AppSwitch kernel module is loaded. If the module is not loaded then user-space driver is used.
--node-interface interface Node interface to use by daemon. Accepts IP address or interface name, eg eth0
The host interface that AppSwitch daemon should use to communicate with its peers on other nodes.
You can specify the interface by name (eg
eth0) or by IP address. If unspecified, it defaults to the first interface listed on the node.
--neighbors csv List (csv) of IP addresses of cluster neighbors
In order to configure more than one node into an AppSwitch cluster you may provide to each node a comma separated list of IP addresses of neighbor nodes.
$ ax daemon --node-interface 192.168.0.2 --neighbors 192.168.0.2,192.168.0.3
--clean Remove any saved state from previous sessions
When AppSwitch daemon is shutdown, the state of sockets maintained on behalf of the applications is saved under /var/run/appswitch. If this flag is set, then any saved state from earlier runs of the daemon is removed before starting the daemon. The default behavior is to restore the saved state.
--node-name name Name of the node (defaults to host name)
Name used to identify the node. Defaults to the host name of the node that the daemon is running on.
--cpu-profile file Write CPU profile output to file --mem-profile file Write memory profile output to file
Golang profiling can be enabled using the
--mem-profile options. Each option sets the file name (relative or
absolute path) for profiling output. Output file is a binary file that can be
viewed using standard
$ ax daemon --cpu-profile /tmp/cpu.prof ... Ctl-C $ go tool pprof /tmp/cpu.prof
Domain Name System¶
--dns Start the built-in DNS server (default: true)
If this flag is set then AppSwitch starts a DNS server on port 53. The
built-in DNS server resolves the names associated with the applications run
under AppSwitch. This option is required to use the
option to the
DNS Configuration Options¶
--dns-domain name DNS domain name suffix (default: "appswitch.local") --dns-servers csv List (csv) of 'IP[:port]' strings of forwarding servers
Configuration options for the built-in DNS server. You can optionally specify a DNS suffix and a list of forwarding DNS servers. For example
$ ax daemon --dns-servers 127.0.0.1:5533,188.8.131.52
Transport Layer Security¶
AppSwitch can be configured to use Transport Layer Security for internal communication among the daemons.
--tls Enable Transport Layer Security
TLS Configuration Options¶
--tls-ca-cert file Path to TLS CA certificate file --tls-cert file Path to TLS certificate file --tls-key file Path to TLS key file
Currently AppSwitch needs the absolute path to all files when configuring TLS. If you create a self signed certificate you can start the AppSwitch daemon like this
$ ax daemon --tls \ --tls-ca-cert /etc/ssl/certs/cacert.pem \ --tls-cert /etc/ssl/certs/ax.crt \ --tls-key /etc/ssl/private/ax.key
--ports csv List (csv) of ports, or port ranges, reserved for applications (default: "40000-60000")
AppSwitch binds application sockets to ports on the host from this port space.
$ ax daemon --ports '4000,6000-8000'
REST Port Number¶
--rest-port number REST API port number (default: 6664)
AppSwitch exposes most of its functionality through the REST API. Most of the the CLI commands are simply a front end to the REST API. This option specifies the port number used for the REST endpoint.
AppSwitch uses Serf as the gossip channel. Serf can be configured with the following options
--gossip-port number Gossip protocol port number (default: 7946) --gossip-auto-discover Auto discover neighbors
--egress-gateway Configure node as egress gateway
If this flag is set, connections to external services would be proxied through this daemon. However, the presence of the intermediate egress gateway would be transparent to the client running under AppSwitch. That is, client would directly connect to the external service and not the egress gateway.
--cluster name Cluster name. Required if cluster is part of a federation
Name used to identify the cluster. All cluster names within a federation must be unique. Cluster name is only needed if this node is part of a cluster that will be part of a federation of clusters. Otherwise the default ‘appswitch’ can be used. All nodes within the cluster should be configured with the same name.
Multiple AppSwitch clusters may be connected together to form a federation (see AppSwitch Hierarchical Model). To achieve this one or more nodes in each cluster must be configured as a federation gateway node. Connections to services from one cluster to another will be made through the federation gateway nodes.
A federation gateway node has two listening services. One, referred to as the egress federation gateway service, accepts connections from other cluster nodes. Data flows out of a cluster via the egress federation gateway service. The second, referred to as the ingress federation gateway service accepts connections on the wide area network from other federation gateway nodes. Data flows into a cluster via the ingress federation gateway service.
Federation Gateway Node Configuration Options¶
--federation-gateway-ip interface IP address or interface name for federation connectivity --federation-gateway-advertise-ip value Required iff proxy node is behind NAT --federation-gateway-port number TCP port number for federation gateway sessions (default: 6660) --federation-gateway-gossip-port number Federation gossip protocol port number (default: 7947) --federation-gateway-neighbors csv List (csv) of IP addresses of federation neighbors (other gateway nodes)
Please note also; when configuring a federation each and every node must be configured with it’s cluster name, and furthermore cluster names must be unique within a federation (See cluster-label for details).
run sub command is used to run an application under AppSwitch.
--ip address IPv4 address at which services of this application would be reachable
The specified IP address is associated with the application. When an AppSwitch-managed client connects to the IP address, it would be automatically directed to the services of this application. To achieve that, a vservice is implicitly created. The same IP address could be used for other applications, in which case, all those applications become backends for the vservice.
DNS Resolvable Name¶
--name value DNS resolvable name of the application
The specified name is associated with the application. When an AppSwitch-managed client looks up this name, it is resolved to the IP address associated with the application by AppSwith daemon’s built-in DNS server.
--labels csv Labels of this application (default: "zone=default")
Allows arbitrary labels of the form
label=value to be associated with
the application. This option accepts a comma separated list of labels all
of which will be associated with the application. Accepts arbitrary string
values for both ‘label’ and ‘value’. A client would be able to reach a
service only if they share at least one matching label. For example, a
client with a label
role=test cannot connect to a service with a label
role=prod or one without any labels.
--expose option is used to expose an internal application port on the cluster node(s) such that the service can be accessed by external non-AppSwitch clients. There are three variations of it:
The specified application port would be exposed on the specified external port only on the node where the application is running.
For example, a python web server (port 8000) can be exposed on external port 9999 as follows:
$ ax run --expose '8000:9999' python -m http.server $ curl -I 192.168.0.2:9999 HTTP/1.0 200 OK Server: SimpleHTTP/0.6 Python/3.5.2 Date: Mon, 30 Apr 2018 05:23:33 GMT Content-type: text/html; charset=utf-8 Content-Length: 2377
The specified application port would be exposed on the specified external port only on the specified node. The specified node-IP must belong to one of the nodes in the AppSwitch cluster.
The specified application port would be exposed on the specified external port on every node in the AppSwitch cluster. This is equivalent to the nodePort feature of Kubernetes. A similar result can also be produced by creating an external vservice.
--user name UID or user name to run the child process
When the client runs an application it is run by default as the same user
that invoked AppSwitch. If AppSwitch is run as root (which is required to
create a new network namespace) then the application being run will be run
as root. This is often not the desired behavior. Using the
option the name or UID of a valid user can be given to the client and the
application being run will be run as that user.
$ ax run -- whoami root $ ax run --user alice whoami alice
--interface name Name of the dummy interface created within the application's network namespace
Some applications require the presence of a non-loopback network interface
in order to function. AppSwitch places the application in a new network
namespace by default. With this option, a dummy interface with the
specified name can be created in the new network namespace before the
application is executed. A new network namespace has, by default, only the
loopback interface. This option requires that
--no-new-netns flag is
$ ax run -- ip addr show 1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1000 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
$ ax run --interface eth0 ip addr show 1: lo: <LOOPBACK> mtu 65536 qdisc noop state DOWN group default qlen 1 link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state UNKNOWN group default qlen 1000 link/ether d2:a0:cb:e5:b0:33 brd ff:ff:ff:ff:ff:ff inet 192.168.178.2/32 scope global eth0 valid_lft forever preferred_lft forever inet6 fe80::d0a0:cbff:fee5:b033/64 scope link valid_lft forever preferred_lft forever
--new-netns Create a new network namespace (default: true)
Each application run by AppSwitch is run in a separate namespace. Creation
of a new namespace is handled by AppSwitch by default. Sometimes this
behavior is not required, for example when running within a Docker
container. Note that creating a new network namespace also requires
privilege. To prevent from new network namespace from being created
--new-netns=false can be used.
--dns-override Take over application's DNS requests (default: true)
This option overrides existing resolv.conf file for the application with
one that points to the built-in DNS server by mounting over it. Host is
not affected by this. To prevent dns override use
get command is used to display current AppSwitch resources.
- The IP address of the host machine is 192.168.178.2
- The daemon was started with:
ax daemon --node-name node1
- Two AppSwitch client instances were started
ax run -- nc -l 6000-
ax run -- iperf3 -s
ax get apps¶
Displays information about applications currently running under AppSwitch
NAME APPID NODEID CLUSTER APPIP DRIVER LABELS ZONES ------------------------------------------------------------------------------------------------------------ <ab856b81-7db0-4d88-8a1e-1bfbf0c5fe9f> f00001bb node1 appswitch 192.168.178.2 user zone=default [zone==default] <04a275bc-b9b4-4496-9c9d-a838daecdffb> f000028e node1 appswitch 192.168.178.2 user zone=default [zone==default]
ax get servers¶
Shows information about currently running services.
NODEID CLUSTER APPID PROTO SERVICEADDR IPV4ADDR -------------------------------------------------------------------------- node1 appswitch f00001bb tcp 192.168.178.2:6000 10.0.23.11:40000 node1 appswitch f000028e tcp 192.168.178.2:5201 10.0.23.11:40001
SERVICEADDR above represents the virtual IP address where the service is available to AppSwitch-managed clients and the IPV4ADDR represents the host IP and port where the service is actually bound.
ax get sockets¶
Displays socket information for currently running applications
ID NODEID APPID INODE PROTO FLAGS BINDIP BACKLOG ---------------------------------------------------------------------------------------------------- 4daa64c4-2091-46e0-8a67-5428fae9775d node1 f00001bb 829 tcp 0 0.0.0.0:6000 1 f6dd4f27-bb4e-4c4a-a076-dc07c29af7be node1 f000028e 833 tcp 0 0.0.0.0:5201 5
Create command is used to create a resource. Resource is a general construct that represents a particular AppSwitch feature.
Currently supported resources are:
vservice Create a virtual service
A virtual service (vservice) is a virtual-IP:virtual-port combination that acts as a load balancing front end to a set of backend services. Backend services consist of services listed in the service table or external services specified as IP:port pairs. The vIP, vPort and the IP:Ports of the backend services are specified by the user.
The following options are provided by vservice command.
--ip value IPv4 address for the virtual service --external Make this vservice external
A virtual service can be marked external. In that case, in addition to creating the vservice with the specified vIP and vPort, the virtual service represented by the load balanced backend services is exposed on the vPort on all nodes of the cluster.
--lbtype value Load Balancer Type <possible values: Random, RoundRobin> (default: "Random") --backends value Comma separated list of IPv4 IPs --ports value Comma separated list of <virtual port:application port>. The service will be made available on all cluster nodes on virtual port --source-ip Host IP address to use when making the outbound connection