



                           GRID ASCII HELPER PROTOCOL
                           for Microsoft Azure Cloud
                                 VERSION 0.2


                                 Jaime Frey
                             [jfrey@cs.wisc.edu]

                                 August 2017

                               HTCondor Project
                    [http://research.cs.wisc.edu/htcondor]

                       Department of Computer Sciences
                       University of Wisconsin-Madison
                            1210 W. Dayton Street
                             Madison, WI  53706
                          [http://www.cs.wisc.edu]





1.    INTRODUCTION

    The object of the Grid ASCII Helper Protocol (GAHP) is to allow the
    use of the client library or package of a grid or cloud service via
    a simple ASCII-based protocol. A process which implements GAHP is
    referred to as a GAHP server. GAHP is designed to handle both
    synchronous (blocking) and asynchronous (non-blocking) calls.

    The first GAHP specification focused on the GRAM and GASS grid
    services of the Globus Toolkit. This GAHP specification focuses on
    the Microsoft Azure cloud service.

1.1   WHY A GAHP?

    Although most grid and cloud services provide client libraries or
    modules in various languages that can be incorporated directly into
    applications that wish to use those services, there are several
    distinct advantages to using an independent GAHP server process
    instead. For instance, parts of the native API may provide only
    synchronous/blocking calls. Users who require a
    non-blocking/asynchronous interface must make use of multiple
    threads. Even if the native module is thread-safe, thread safety
    requires that _all_ modules linked into the process be both
    re-entrant and in agreement upon a threading model.
    This may be a significant barrier when trying to integrate the
    service client module into legacy non-thread-safe code, or when
    attempting to link with commercial libraries which either have no
    support for threads or define their own threading model. But because
    the GAHP server runs as a separate process, it can be easily
    implemented as a multi-threaded server, and still present an
    asynchronous non-blocking protocol. Worse yet, there may not be a
    client module available in the language of the application wishing
    to use the service. With a GAHP server, langauage choice is
    immaterial.

    GAHP facilitates the construction of multi-tier systems.  A first
    tier client can easily send ASCII commands via a socket (perhaps
    securely via an SSH or SSL tunnel) to a second tier running a GAHP
    server, allowing grid or cloud services to be consolidated at the
    second or third tier with minimal effort.

    Furthermore, GAHP, like many other simple ASCII-based protocols,
    supports the concept of component-based development independent of
    the software language used with minimal complexity. When a grid
    service has client modules available in multiple languages, those
    interfaces can look very different from each other. By using GAHP, a
    body of software could be written once with one interface and then
    subsequently utilize a GAHP server written in C, Java, or Perl --
    and said GAHP server could be running locally or as a daemon on a
    remote host.

1.2   AVAILABLE AZURE GAHP SERVERS

    The Center for High Throughput Computing at the University of
    Wisconsin-Madison and Microsoft have developed an Azure GAHP server,
    written in Python, which uses the Azure SDK to support portions of
    the Azure REST protocol.

2.0   GAHP SERVER IMPLEMENTATION

    GAHP itself, as a protocol, is independent of the underlying transport
    protocol and requires only a reliable ordered bi-directional data
    stream channel.

    A GAHP server, however, is assumed to read and respond to GAHP commands
    solely via stdin and stdout.  Should stdin to a GAHP server be closed,
    the GAHP server should immediately shutdown in a manner similar to the
    receipt of a QUIT command.  Therefore, a GAHP server can be easily
    invoked and managed via SSHD, inted, or rshd.  Software can spawn a
    local GAHP server via an interface such as POSIX.2 popen().

    Under no circumstances should a GAHP server block when issued any
    command.  All commands require a response nearly instantaneously.
    Therefore, most GAHP servers will be implemented as a multi-threaded
    process. Use of child processes or avoidance of blocking calls
    within the GAHP server are also options.

3.0   GAHP COMMANDS

    The following commands must be implemented by all GAHP servers:

        COMMANDS
        QUIT
        RESULTS
        VERSION

    The following commands may be implemented by any GAHP server:

        ASYNC_MODE_ON
        ASYNC_MODE_OFF
        RESPONSE_PREFIX

    The following commands are specific to Azure and must be implemented
    by an Azure GAHP server:

        AZURE_PING
        AZURE_VM_CREATE
        AZURE_VM_DELETE
        AZURE_VM_LIST
        AZURE_VMSS_CREATE
        AZURE_VMSS_DELETE
        AZURE_VMSS_START
        AZURE_VMSS_STOP
        AZURE_VMSS_RESTART
        AZURE_VMSS_SCALE

3.1   CONVENTIONS AND TERMS USED IN SECTION 3.2

    The following definitions are common to all GAHP protocol documents.

    <CRLF>

        The characters carriage return and line feed (in that
        order), _or_ solely the line feed character.

    <SP>

        The space character.

    line

        A sequence of ASCII characters ending with a <CRLF>.

    Request Line

        A request for action on the part of the GAHP server.

    Return Line

        A line immediately returned by the GAHP server upon
        receiving a Request Line.

    Result Line

        A line sent by the GAHP server in response to a RESULTS
        request, which communicates the results of a previous
        asynchronous command Request.

    S: and R:

        In the Example sections for the commands below, the prefix
        "S: " is used to signify what the client sends to the GAHP
        server.   The prefix "R: " is used to signify what the
        client receives from the GAHP server.  Note that the "S: "
        or "R: " should not actually be sent or received.

3.2   GAHP COMMAND STRUCTURE

    GAHP commands consist of three parts:

        * Request Line
        * Return Line
        * Result Line

    Each of these "Lines" consists of a variable length character
    string ending with the character sequence <CRLF>.

    A Request Line is a request from the client for action on the part of
    the GAHP server.  Each Request Line consists of a command code
    followed by argument field(s).  Command codes are a string of
    alphanumeric and underscore characters.  Upper and lower case
    alphabetic characters are to be treated identically with respect to
    command codes.  Thus, any of the following may represent the
    ASYNC_MODE_ON command:
        async_mode_on
        Async_Mode_On
        asYNc_MOde_oN
        ASYNC_MODE_ON
    In contrast, the argument fields of a Request Line are _case
    sensitive_.

    The Return Line is always generated by the server as an immediate
    response to a Request Line.  The first character of a Return Line will
    contain one of the following characters:
        S - for Success
        F - for Failure
        E - for a syntax or parse Error
    Any Request Line which contains an unrecognized or unsupported command,
    or a command with an insufficient number of arguments, will generate an
    "E" response.

    The Result Line is used to support commands that would otherwise
    block.  Any GAHP command which may require the implementation to block
    on network communication require a "request id" as part of the Request
    Line.  For such commands, the Result Line just communicates if the
    request has been successfully parsed and queued for service by the
    GAHP server.  At this point, the GAHP server would typically dispatch
    a new thread to actually service the request.  Once the request has
    completed, the dispatched thread should create a Result Line and
    enqueue it until the client issues a RESULT command.

3.3   TRANSPARENCY

    Arguments on a particular Line (be it Request, Return, or Result) are
    typically separated by a <SP>.  In the event that a string argument
    needs to contain a <SP> within the string itself, it must be escaped
    by placing a backslash ("\") in front of the <SP> character.  Thus,
    the character sequence "\ " (no quotes) must not be treated as a
    separator between arguments, but instead as a space character within a
    string argument. If a string argument contains a backslash
    character, it must be escaped by preceding it with another backslash
    character.

3.4   SEQUENCE OF EVENTS

    Upon startup, the GAHP server should output to stdout a banner string
    which is identical to the output from the VERSION command without the
    beginning "S " sequence (see example below).  Next, the GAHP server
    should wait for a complete Request Line from the client (from stdin).
    The server is to take no action until a Request Line sequence is
    received.

    There are no sequencing restrictions on the ordering of Requests in
    the GAHP API, even though some sequences may be semantically
    invalid for the underlying service. For example, attempting to
    delete a new instance before creating it. The server shall not
    produce an "E" or "F" Return Line in the event of such sequences,
    but may produce a Result Line reflecting an error from the
    underlying service.

3.5   COMMAND SYNTAX

    This section contains the syntax for the Request, Return, and Result
    line for each command. The commands common to all GAHPs are defined
    first, followed by commands specific to the Azure GAHP procotol.

3.5.1 COMMON GAHP COMMANDS

    These commands are common to all GAHP types.

    -----------------------------------------------

    COMMANDS

    List all the commands from this protocol specification which are
    implemented by this GAHP server.

    + Request Line:

        COMMANDS <CRLF>

    + Return Line:

        S <SP> <command 1> <SP> <command 2> <SP> ... <command X> <CRLF>

    + Result Line:

        None.

    -----------------------------------------------

    VERSION

    Return the version string for this GAHP.  The version string follows
    a specified format (see below).  Ideally, the version entire version
    string, including the starting and ending dollar sign ($)
    delimiters, should be a literal string in the text of the GAHP
    server executable.  This way, the Unix/RCS "ident" command can
    produce the version string.

    The version returned should correspond to the version of the
    protocol supported.

    + Request Line:

        VERSION <CRLF>

    + Return Line:

        S <SP> $GahpVesion: <SP> <major>.<minor>.<subminor> <SP>
            <build-month> <SP> <build-day-of-month> <SP>
            <build-year> <SP> <general-descrip> <SP>$ <CRLF>

        * major.minor.subminor = for this version of the
            protocol, use version x.y.z.

        * build-month = string with the month abbreviation when
            this GAHP server was built or released.  Permitted
            values are: "Jan", "Feb", "Mar", "Apr", "May", "Jun",
            "Jul", "Aug", "Sep", "Oct", "Nov", and "Dec".

        * build-day-of-month = day of the month when GAHP server
            was built or released; an integer between 1 and 31
            inclusive.

        * build-year = four digit integer specifying the year in
            which the GAHP server was built or released.

        * general-descrip = a string identifying a particular
            GAHP server implementation.

    + Result Line:

        None.

    + Example:

        S: VERSION
        R: S $GahpVersion: 1.0.0 Nov 26 2001 NCSA\ CoG\ Gahpd $

    -----------------------------------------------

    QUIT

    Free any/all system resources (close all sockets, etc) and terminate
    as quickly as possible.

    + Request Line:

        QUIT <CRLF>

    + Return Line:

        S <CRLF>

        Immediately afterwards, the command pipe should be closed
        and the GAHP server should terminate.

    + Result Line:

        None.

    -----------------------------------------------

    RESULTS

    Display all of the Result Lines which have been queued since the
    last RESULTS command was issued.  Upon success, the first return
    line specifies the number of subsequent Result Lines which will be
    displayed.  Then each result line appears (one per line) -- each
    starts with the request ID which corresponds to the request ID
    supplied when the corresponding command was submitted.  The exact
    format of the Result Line varies based upon which corresponding
    Request command was issued.

    IMPORTANT: Result Lines must be displayed in the _exact order_ in
    which they were queued!!!  In other words, the Result Lines
    displayed must be sorted in the order by which they were placed into
    the GAHP's result line queue, from earliest to most recent.

    + Request Line:

        RESULTS <CRLF>

    + Return Line(s):

        S <SP> <num-of-subsequent-result-lines> <CRLF>
        <reqid> <SP> ... <CRLF>
        <reqid> <SP> ... <CRLF>
        ...

        * reqid = integer Request ID, set to the value specified in
            the corresponding Request Line.

    + Result Line:

        None.

    + Example:

        S: RESULTS
        R: S 1
        R: 100 0

    -----------------------------------------------

    ASYNC_MODE_ON

    Enable Asynchronous notification when the GAHP server has results
    pending for a client. This is most useful for clients that do not
    want to periodically poll the GAHP server with a RESULTS command.
    When asynchronous notification mode is active, the GAHP server will
    print out an 'R' (without the quotes) on column one when the
    'RESULTS' command would return one or more lines. The 'R' is printed
    only once between successive 'RESULTS' commands.    The 'R' is
    also guaranteed to only appear in between atomic return lines; the
    'R" will not interrupt another command's output.

    If there are already pending results when the asynchronous results
    available mode is activated, no indication of the presence of those
    results will be given. A GAHP server is permitted to only consider
    changes to it's result queue for additions after the ASYNC_MODE_ON
    command has successfully completed. GAHP clients should issue a
    'RESULTS' command immediately after enabling asynchronous
    notification, to ensure that any results that may have been added to
    the queue during the processing of the ASYNC_MODE_ON command are
    accounted for.

    + Request Line:

        ASYNC_MODE_ON <CRLF>

    + Return Line:

        S <CRLF>

        Immediately afterwards, the client should be prepared to
        handle an R <CRLF> appearing in the output of the GAHP
        server.

    + Result Line:

        None.

    + Example:

        S: ASYNC_MODE_ON
        R: S
        S: GRAM_PING 00001 beak.cs.wisc.edu/jobmanager
        R: S
        S: GRAM_PING 00002 nostos.cs.wisc.edu/jobmanager
        R: S
        R: R
        S: RESULTS
        R: S 2
        R: 00001 0
        R: 00002 0

    Note that you are NOT guaranteed that the 'R' will not appear
    between the dispatching of a command and the return line(s) of that
    command; the GAHP server only guarantees that the 'R' will not
    interrupt an in-progress return. The following is also a legal
    example:
        S: ASYNC_MODE_ON
        R: S
        S: GRAM_PING 00001 beak.cs.wisc.edu/jobmanager
        R: S
        S: GRAM_PING 00002 nostos.cs.wisc.edu/jobmanager
        R: R
        R: S
        S: RESULTS
        R: S 2
        R: 00001 0
        R: 00002 0

        (Note the reversal of the R and the S after GRAM_PING 00002)

    -----------------------------------------------

    ASYNC_MODE_OFF

    Disable asynchronous results-available notification. In this mode,
    the only way to discover available results is to poll with the
    RESULTS command.  This mode is the default. Asynchronous mode can be
    enable with the ASYNC_MODE_ON command.

    + Request Line:

        ASYNC_MODE_OFF <CRLF>

    + Return Line:

        S <CRLF>

    + Result Line:

        None

    + Example:

        S: ASYNC_MODE_OFF
        R: S

    -----------------------------------------------

    RESPONSE_PREFIX

    Specify a prefix that the GAHP server should use to prepend every
    subsequent line of output. This may simplify parsing the output of
    the GAHP server by the client program, especially in cases where the
    responses of more one GAHP server are "collated" together.

    This affects the output of both return lines and result lines for all
    subsequent commands (NOT including this one).

    + Request Line:

        RESPONSE_PREFIX <SP> <prefix> <CRLF>

        <prefix> = an arbitrary string of characters which you want to
        prefix every subsequent line printed by the GAHP server.

    + Return Line:

        S <CRLF>

    + Result Line:

        None.

    + Example:

        S: RESPONSE_PREFIX GAHP:
        R: S
        S: RESULTS
        R: GAHP:S 0
        S: RESPONSE_PREFIX NEW_PREFIX_
        R: GAHP:S
        S: RESULTS
        R: NEW_PREFIX_S 0

    -----------------------------------------------

3.5.2 GAHP COMMANDS SPECIFIC TO AZURE

    The following commands are specific to the Azure GAHP. All commands
    will include the following arguments.

    * request-ID    = a non-zero Request ID
    * cred-file     = the full path to a file containing a valid set of
                      OAuth credentials in the JSON format used
                      by Azure's az command-line client program
    * subscription  = the Azure subscription to be used

    We do not directly specify keys to minimize the chance of interception.

    Required values must not be the literal string "NULL" (without the
    quotes), as this denotes that the corresponding attribute was not set.
    If an optional value is not set, it _must_ be represented in this way.

    The following is the Return Line for all Azure GAHP commands unless
    otherwise specified.

    + Return Line:

        <result> <CRLF>

        * result             = the character "S" (without the quotes) for
                               the successful submission of the request
                               (meaning the request is now pending), or an
                               "E" (without the quotes) for an error
                               parsing the request or its arguments (e.g.
                               an unrecognized or unsupported command, or
                               missing or malformed arguments)

    The following is the Result Line for all Azure GAHP commands unless
    otherwise specified.

    + Result Line:

        <request-ID> <SP> <error-string> <CRLF>

        If the command was successful, <error-string> shall be the
        special value "NULL" (with no quotes). Otherwise, it should be a
        string describing the nature of the failure.

    -----------------------------------------------

    AZURE_PING

    Send a simple request to the Azure service in order to determine if
    it is alive, reachable, responds to queries, and accepts the provided
    credentials.

    + Request Line:

        AZURE_PING <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <CRLF>

    -----------------------------------------------

    AZURE_VM_CREATE

    Create a VM and associated resources in a new resource group with
    the given properties.

    + Request Line:

        AZURE_VM_CREATE <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> [<SP> <key>=<value>]* <CRLF>

        The following key/value pairs are required.

        * name: a unique name for this VM
        * location: the Azure location where this VM should reside
        * size: the hardware configuration, represented as the vmSize
            element of the VM's description
        * image: the image from which the OS disk should be created

        The following key/value pairs are optional.

        * dataDisks: a comma-separated list of data disks sizes in GB
            that should be created for this VM
        * adminUsername: user account that should be created in the VM
        * key: an SSH public key or public key file path, or a password
            for the admin account
        * vnetName: resource id of a virtual network to use.
            If omitted, create a virtual network for this VM.
        * vnetRGName: resource group containing the virtual network
            named by the vnetName attribute
        * publicIPAddress: resource id of a public IP address to use,
            or the string 'dynamic' to indicate one should be created
        * customData: custom init script file or text
        * tag: a name/value pair that should be a tag on the VM
            resource. This option can be given multiple times with
            different names, and the value is optional.

    + Result Line:

        One of the following. The first should be used if the command
        failed. The second should be used if the command succeeded.

        <request-ID> <SP> <error-string> <CRLF>
        <request-ID> <SP> NULL <SP> <vm-id> <SP> <ip-address> <CRLF>

        * error-string = string describing the nature of the failure
        * vm-id = the vmId attribute of the VM
        * ip-address = the public IP address of the VM, or NULL if none.

    -----------------------------------------------

    AZURE_VM_DELETE

    Delete the given VM (halting exeucting and releasing all resources).

    + Request Line:

        AZURE_VM_DELETE <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <SP> <name> <CRLF>

        The following attribute is required.

        * name = the name for the VM as given in AZURE_VM_CREATE

    -----------------------------------------------

    AZURE_VM_LIST

    Query the status of all VMs under the given subscription.
    This may include VMs not started by the GAHP; the client must
    maintain its own list of VMs if it cares.

    + Request Line:

        AZURE_VM_LIST <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> [<SP> <id>] <CRLF>

        * id = either the name given in a AZURE_VM_CREATE request or a
            tag name with optional value

    + Result Line:

        One of the following. The first should be used if the command
        failed. The second should be used if the command succeeded.

        <request-ID> <SP> <error-string> <CRLF>
        <request-ID> <SP> NULL <SP> <count>
            [<SP> <name> <SP> <status> ]* <CRLF>

        * error-string = string describing the nature of the failure
        * count = the number of VMs whose information will follow
        * name = the name of the VM as given in AZURE_VM_CREATE
        * status = the 'powerState' property of the VM

        On success, <count> is an integer indicating the number of
        VMs returned by the query. It is followed by the given
        four properties of each vm. If the command was successful
        but returned no vms, then <count> is 0 and no arguments
        follow it.

    -----------------------------------------------

    AZURE_VMSS_CREATE

    Create a VM scale set and associated resources in a new resource
    group with the given properties.

    + Request Line:

        AZURE_VMSS_CREATE <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> [<SP> <key>=<value>]* <CRLF>

        The following key/value pairs are required.

        * name: a unique name for this scale set
        * location: the Azure location where this scale set should
            reside
        * size: the hardware configuration, represented as the vmSize
            element of the VM's description
        * image: the image from which the OS disk should be created
        * nodecount: the number of VMs in the scale set

        The following key/value pairs are optional.

        * dataDisks: a comma-separated list of data disks sizes in GB
            that should be created for this VM
        * adminUsername: user account that should be created in the VMs
        * key: an SSH public key or public key file path, or a password
            for the admin account
        * vnetName: resource id of a virtual network to use.
            If omitted, create a virtual network for these VMs.
        * vnetRGName: resource group containing the virtual network
            named by the vnetName attribute
        * publicIPAddress: resource id of a public IP address to use,
            or the string 'dynamic' to indicate one should be created
        * customData: custom init script file or text
        * tag: a name/value pair that should be a tag on the scale set
            resource. This option can be given multiple times with
            different names, and the value is optional.
        * deletionjob: indicates that this scale set should be
            automatically deleted at a time given by the attribute
            'schedule'
        * schedule: a time at which the scale set should be
            automatically deleted. The format of the value is
            YYYYMMDDhhmm in UTC.
        * keyvaultname: name of a key vault from which a secret will be
            obtained and inserted in the the VMs
        * vaultkey: name of a secret in the key vault named by
            'keyvaultname', which will be obtained and inserted in the
            VMs

    -----------------------------------------------

    AZURE_VMSS_DELETE

    Delete the given scale set (halting exeucting and releasing all
    resources).

    + Request Line:

        AZURE_VMSS_DELETE <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <SP> <name> <CRLF>

        The following attribute is required.

        * name = the name for the scale set as given in
            AZURE_VMSS_CREATE

    -----------------------------------------------

    AZURE_VMSS_START

    Start the VMs in the given scale set.

    + Request Line:

        AZURE_VMSS_START <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <SP> <name> <CRLF>

        The following attribute is required.

        * name = the name for the scale set as given in
            AZURE_VMSS_CREATE

    -----------------------------------------------

    AZURE_VMSS_STOP

    Stop the VMs in the given scale set.

    + Request Line:

        AZURE_VMSS_STOP <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <SP> <name> <CRLF>

        The following attribute is required.

        * name = the name for the scale set as given in
            AZURE_VMSS_CREATE

    -----------------------------------------------

    AZURE_VMSS_RESTART

    Restart the VMs in the given scale set.

    + Request Line:

        AZURE_VMSS_RESTART <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <SP> <name> <CRLF>

        The following attribute is required.

        * name = the name for the scale set as given in
            AZURE_VMSS_CREATE

    -----------------------------------------------

    AZURE_VMSS_SCALE

    Change the number of VMs in the given scale set.

    + Request Line:

        AZURE_VMSS_SCALE <SP> <request-ID> <SP> <cred-file>
            <SP> <subscription> <SP> name=<name> <SP>
            nodecount=<count> <CRLF>

        The following attribute is required.

        * name = the name for the scale set as given in
            AZURE_VMSS_CREATE
        * count = the new number of VMs in the scale set
