Service Commander for IBM i

Introduction

A utility for unifying the daunting task of managing various services and applications running on IBM i. Its objective is to provide an intuitive, easy-to-use command line interface for managing services or jobs. It also provides integration with STRTCPSVR.

Service Commander can be used to manage a number of services, for instance:

• IBM i host server jobs
• IBM i standard TCP servers (*FTP, *SSHD, etc.)
• Programs you wrote using open source technology (Node.js, Python, PHP, etc.)
• Apache Tomcat instances
• Apache Camel routes
• Kafka, Zookeeper, ActiveMQ servers, etc
• Jenkins
• The Cron daemon
• OSS Database servers (PostgreSQL, MariaDB)

Current features

Some of the features of the tool include:

• The ability to specify dependencies (for instance, if one application or service depends on another), and it will start any dependencies as needed
• The ability to submit jobs to batch easily, even with custom batch settings (use your own job description or submit as another user, for instance)
• The ability to check the “liveliness” of your service by either port status or job name
• Customize the runtime environment variables of your job
• Define custom groups for your services, and perform operations on those groups (by default, a group of “all” is defined)
• Query basic performance attributes of the services
• Assistance in providing/managing log files. This is a best-guess only and naively assumes the service uses stdout/stderr as its logging mechanism. Service Commander has its own primitive logging system that works well only for certain types of services
• Ability to define manage ad hoc services specified on the command line
• Ability to see what ports are currently open (have a job listening)

Important differences from other service management tools

Service Commander’s design is fundamentally different from other tools that accomplish similar tasks, like init.d, supervisord, and so on. Namely, the functions within Service Commander are intended to work regardless of:

• Who else may start or stop the service
• What other tools may be used to start or stop the service. For instance, Service Commander may start/stop an IBM i host server, but so could the STRHOSTSVR/ENDHOSTSVR CL commands.
• Whether the service runs in the initially spawned job or a secondary job

Also, this tool doesn’t have the privilege of being the unified, integrated solution with the operating system that other tools may have. Therefore, Service Commander cannot take the liberty of assuming that it can keep track of the resources tied to the services that it manages. So, for example, Service Commander does not keep track of process IDs of launched processes. Similarly, it doesn’t have special access to kernel data structures, etc.

Instead, Service Commander makes strong assumptions based on checks for a particular job name or port usage (see check_alive in the file format documentation). A known limitation, therefore, is that Service Commander may mistake another job for a configured service based on one of these attributes. For example, if you configure a service that is supposed to be listening on port 80, Service Commander will assume that any job listening on port 80 is indeed that service.

Service Commander’s unique design is intended to offer a great deal of flexibility and ease of management through the use of simple .yaml files.

Installation

System Requirements

For most of the features of Service Commander, the following is required to be installed (the installation steps should handle these for you):

• db2util (yum install db2util)
• OpenJDK (yum install openjdk-11)
• bash (yum install bash)
• GNU coreutils (yum install coreutils-gnu)

(click here to read more about the requirements for db2util and openjdk-11.)

The performance information support (perfinfo) has additional requirements that are not automatically installed, including:

• Python 3 with the ibm_db database connector (yum install python3-ibm_db)

• Required operating system support, which depends on your IBM i operating system level, as follows:

  • IBM i 7.4: included with base OS
  • IBM i 7.3: Group PTF SF99703 Level 11
  • IBM i 7.2: Group PTF SF99702 Level 23
  • IBM i 7.1 (and earlier): not supported

Option 1: Binary distribution

You can install the binary distribution by installing the service-commander package:

yum install service-commander

If you are not familiar with IBM i RPMs, see this documentation to get started.

Option 2: Build from source (for development or fix evaluation)

Feel free to build from the main branch to start making code contributions or to evaluate a fix/feature not yet published. This process assumes your PATH environment variable is set up properly, otherwise:

PATH=/QOpenSys/pkgs/bin:$PATH
export PATH

The build itself can be done with the following steps:

yum install git ca-certificates-mozilla make-gnu
git clone https://github.com/ThePrez/ServiceCommander-IBMi/
cd ServiceCommander-IBMi
make install_with_runtime_dependencies

Option 3: Install from release on GitHub

If you need any binary distribution of Service Commander not yet in the IBM repository but available as a release on GitHub, you can install the release using yum and the URL of the RPM release file:

yum install https://github.com/ThePrez/ServiceCommander-IBMi/releases/download/v1.4.3/service-commander-1.4.3-0.ibmi7.2.ppc64.rpm

This will install release 1.4.3 from the RPM file on GitHub.

Hands-on Exercise

Want to walk through a quick exercise to get some basic “hands-on” experience with this tool? If so, please see our very simple hands-on exercise

Basic usage

Usage of the command is summarized as:

Usage: sc  [options] <operation> <service>

    Valid options include:
        -v: verbose mode
        -q: quiet mode (suppress warnings). Ignored when '-v' is specified
        --disable-colors: disable colored output
        --splf: send output to *SPLF when submitting jobs to batch (instead of log)
        --sampletime=x.x: sampling time(s) when gathering performance info (default is 1)
        --ignore-globals: ignore globally-configured services
        --ignore-groups=x,y,z: ignore services in the specified groups (default is 'system')
        --all/-a: don't ignore any services. Overrides --ignore-globals and --ignore-groups

    Valid operations include:
        start: start the service (and any dependencies)
        stop: stop the service (and dependent services)
        kill: stop the service (and dependent services) forcefully
        restart: restart the service
        check: check status of the service
        info: print configuration info about the service
        jobinfo: print basic performance info about the service
        perfinfo: print basic performance info about the service
        loginfo: get log file info for the service (if running)
        list: print service short name and friendly name
        groups: print an overview of all groups

    Valid formats of the <service(s)> specifier include:
        - the short name of a configured service
        - A special value of "all" to represent all configured services (same as "group:all")
        - A group identifier (e.g. "group:groupname")
        - the path to a YAML file with a service configuration
        - An ad hoc service specification by port (for instance, "port:8080")
        - An ad hoc service specification by job name (for instance, "job:ZOOKEEPER")
        - An ad hoc service specification by subsystem and job name (for instance, "job:QHTTPSVR/ADMIN2")

The above usage assumes the program is installed with the above installation steps and is therefore launched with the sc script.

Usage examples

Start the service named kafka:

sc start kafka

Stop the service named zookeeper:

sc stop zookeeper

Check status of all configured services (all services belong to a special group named “all”)

sc check group:all

Try to start all configured services

sc start group:all

Print information about all configured services

sc info group:all

Try to start all services in “host_servers” group

sc start group:host_servers

List all services

sc list group:all

List jobs running on port 8080

sc jobinfo port:8080

Stop jobs running on port 8080

sc stop port:8080

Check if anything is running on port 8080

sc check port:8080

Start the service defined in a local file, myservice.yml

sc start myservice.yml

List all groups

sc groups

Only list groups that are defined within the users private YAML configuration files

sc groups --ignore-globals

Command for checking which ports are currently open

Service Commander (>=0.7.x) also comes with command scopenports that allow you to see which ports are open. Usage is as follows:

Usage: scopenports  [options]

    Valid options include:
        -v: verbose mode
        --mine: only show ports that you have listening

See what ports are currently listening

scopenports

Example output when invoked with the --mine option:

The value in the service name column can be used with the sc command. For instance, with the above example, if I wanted to see which job was running on port 62006, I could run

sc jobinfo port:62006

Important Note: Currently, scopenports can only show human-readable descriptions for services that have been configured for sc’s use. To populate some common defaults, run sc_install_defaults.

Special system group (hidden by default)

Service Commander ships a handful of pre-made configurations for common system services. These include things like:

• IBM i host servers
• common system services (like ftp, ssh, etc)
• Administration interfaces (like Navigator for i)

By default, the sc command ignores these system services. So, for instance, if you run sc check all, it will omit these preconfigured system services. In order to include them, use the -a option, for instance sc -a check all.

List all services in the special “system” group

sc list group:system

List all services including those in the special “system” group

sc -a list group:all

Specifying options in environment variables

If you would like to set some of the tool’s options via environment variable, you may do so with one of the following:

• SC_TCPSVR_OPTIONS, which will be processed when invoked via the STRTCPSVR/ENDTCPSVR commands
• SC_OPTIONS, which will be processed on all invocations For example, to gather verbose output when using STRTCPSVR, run the following before your STRTCPSVR command:

ADDENVVAR ENVVAR(SC_OPTIONS) VALUE('-v') REPLACE(*YES)

Configuring Services

Initializing your configuration with defaults

If you’d like to start with pre-made configurations for common services, simply run the sc_install_defaults command. Its usage is as follows:

usage: sc_install_defaults [options]

    valid options include:
        -h            : display help
        --apache      : autocreate from apache instances (default)
        --cleanupv0   : clean up files created by v0 (default)
        --cleanup     : clean up previously-generated configs (default)
        --noapache    : don't autocreate from apache instances
        --nocleanupv0 : don't clean up files created by v0
        --nocleanup   : don't clean up previously-generated configs
        --global      : install for all users
        --user        : install for current user (default)

This will install service definitions for:

• The Cron daemon (if you have the cronie package installed)
• MariaDB (if you have the mariadb package installed)
• IBM i HTTP Server (DG1) instances (unless you specify --noapache)

Important Note 1: Services installed with this utility will be in a special group named autogenerated. This group is used by the --cleanup option when re-running the script.

Important Note 2: If you ran this tool with v0.x, you will want to clean up the old configurations by running:

sc_install_defaults --cleanupv0

Using the ‘scinit’ tool

You can use the scinit tool to create the YAML configuration files for you. Basic usage of the tool is simply:

scinit <program start command>

The idea is that you would simply:

1. cd to the directory where you’d normally start the service
2. Run the command you’d normally use to start the service, prefixed by scinit
3. Answer a series of questions about how you would like the service deployed

In doing so, the scinit will create the YAML configuration file for you and also show you information about the newly-configured service.

For instance, if you would normally launch a Node.js application from /home/MYUSR/mydir by running node app.js, you would run:

cd /home/MYUSR/mydir
scinit node app.js

The scinit tool will ask you for a “short name” among other things. When done, a service configuration will be saved under that short name. So, for instance, if your short name is “my_node_app”, you can run sc start my_node_app.

Using the ‘scedit’ tool

You can use the scedit tool to edit the already created YAML configuration files. Basic usage of the tool is simply:

scedit <service>

When activated, scedit will locate the YAML file for the service and open the file in the first of the following editors:

1. The editor specified in the $EDITOR environment variable. This is the recommended way of specifying the editor you want out of all editors installed
2. The nano editor
3. The joe editor
4. The vim editor
5. The vi editor

Ad hoc service definition

Ad hoc services can be specified on the sc command line in the format job:jobname or port:portname. In these instances, the operations will be performed on the specified jobs. This is determined by looking for jobs matching the given job name or listening on the given port. The job name can be specified either in jobname or subsystem/jobname format. It can also be specified in PGM-____ format to check for jobs running a certain program from the main thread.

If an existing service definition is found (configured via YAML, as in the preceding section) that matches the job name or port criteria, that service will be used. For instance, if you have a service configured to run on port 80, then specifying sc info port:80 will show information about the service configured to run on port 80.

Ad hoc service definition is useful for quick checks without the need to create a YAML definition. It’s also useful if you do not recall the service name, but remember the job name or port.

It is also useful for cases where you just want to find out who (if anyone) is using a certain port. For instance, sc jobinfo port:8080 will show you which job is listening on port 8080. Similarly, sc stop port:8080 will kill whatever job is running on port 8080.

Directly creating/editing YAML configuration files

Service Commander allows you to define any services of interest in .yaml files. These files can be stored in any of the following locations:

• A global directory (/QOpenSys/etc/sc/services). This, of course, requires you to have admin access (*ALLOBJ special authority).
• A user-specific directory($HOME/.sc/services)
• If defined, whatever the value of the services.dir system property is.

The file name must be in the format of service_name.yaml (or service_name.yml), where “service_name” is the “simple name” of the service as to be used with this tool’s CLI. The service name must consist of only lowercase letters, numbers, hyphens, and underscores.

The file can also be located in any arbitrary directory, but it must be explicitly passed along to the sc command, for instance:

sc start /tmp/my_service.yml

YAML File Format

See the samples directory for some sample service definitions. The following attributes may be specified in the service definition (.yaml) file:

Required fields

• start_cmd: The command used to start the service
• check_alive: How to check whether the service is alove or not. This can be a port number, or a job name in either the the format “jobname” or “subsystem/jobname”. It can also be specified in PGM-____ format to check for jobs running a certain program from the main thread. To specify multiple criteria, just use a comma-separated list or a YAML String array.

Optional fields that are often needed/wanted

• name: A “friendly” name of the service
• dir: The working directory in which to run the startup/shutdown commands

Other optional fields

• stop_cmd: The service shutdown command. If unspecified, the service will be located by port number or job name.
• startup_wait_time: The wait time, in seconds, to wait for the service to start up (the default is 60 seconds if unspecified)
• stop_wait_time: The wait time, in seconds, to wait for the service to stop (the default is 45 seconds if unspecified)
• log_dir: The directory for storing log files created by Service Commander
• cluster: Enable cluster mode by providing a comma-separated list of ports (see Cluster Mode below)
• batch_mode: Whether or not to submit the service to batch
• sbmjob_jobname: If submitting to batch, the custom job name to be used for the batch job
• sbmjob_opts: If submitting to batch, custom options for the SBMJOB command (for instance, a custom JOBD)
• environment_is_inheriting_vars: Whether the service inherits environment variables from the current environment (default is true)
• only_if_executable: This configuration is ignored unless the specified file exists and is executable
• environment_vars: Custom environment variables to be set when launching the service. Specify as an array of strings in "KEY=VALUE" format
• service_dependencies: An array of services that this service depends on. This is the simple name of the service (for instance, if the dependency is defined as “myservice”, then it is expected to be defined in a file named myservice.yaml), not the “friendly” name of the service.
• groups: Custom groups that this service belongs to. Groups can be used to start and stop sets of services in a single operation. Specify as an array of strings.

Deprecated fields

• check_alive_criteria: The criteria used when checking whether the service is alive or not. If check_alive is set to “port”, this is expected to be a port number. If check_alive is set to “jobname”, this is expect to be be a job name, either in the format “jobname” or “subsystem/jobname”. It can also be specified in PGM-____ format to check for jobs running a certain program from the main thread. This field is deprecated. As of v1.0.0, the check_alive field handles both port numbers and job names (or a list containing both).

YAML file example

The following is an example of a simple configuration for a Node.js application that runs on port 80:

name: My Node.js application
dir: /home/MYUSER/myapp
start_cmd: node index.js
check_alive: '80'
batch_mode: 'false'
environment_vars:
- PATH=/QOpenSys/pkgs/bin:/QOpenSys/usr/bin:/usr/ccs/bin:/QOpenSys/usr/bin/X11:/usr/sbin:.:/usr/bin

Advanced usage

Cluster Mode

Service Commander allows for the automatic “clustering” of your applications. When utilizing “cluster mode”:

• Service Commander will start n worker jobs, each running on a different port
• Service Commander will manage the worker jobs when performing operations on the service
• Work is load-balanced across the worker jobs as needed

For example, imagine a service configured like this:

name: Active Jobs Dashboard
dir: /home/JGORZINS/ibmi-oss-examples/python/active-jobs-dashboard
start_cmd: python3.9 ./server.py
check_alive: 9333

In standard operation, this example would start up a Python web server that listens on port 9333. Cluster mode can be easily enabled with the cluster value. The cluster value provides a set of ports for the worker jobs to listen on. The number of backend workers is simply based on the quantity of ports specified in this property.

In this example, we run the same Python web server with cluster mode, using 4 backend jobs:

name: Active Jobs Dashboard
dir: /home/JGORZINS/ibmi-oss-examples/python/active-jobs-dashboard
start_cmd: python3.9 ./server.py
cluster: 9334,9335,9336,9337
check_alive: 9333

The application is still expected to run on 9333, so in the case of a web server, it would still run at http://<system_name>:9333. Service Commander will run four backend worker jobs, running on ports 9334, 9335, 9336 and 9337.

Prerequisites for Cluster Mode

In order for cluster mode to work correctly, your application must honor the PORT environment variable. If the technology has the ability to run on dynamically-defined ports but cannot recognize PORT, then the program startup can be wrapped in a script that transposes the environment variable to a command line option. For instance:

#!/QOpenSys/pkgs/bin/bash
exec ./startup.sh --port=$PORT

In case the application requires more than one port, Service Commander also provides these environment variables to the backend worker jobs, which can then be used to run the different components of the backend worker with different ports:

• PORT_PLUS_1
• PORT_PLUS_2
• PORT_PLUS_3
• PORT_PLUS_4
• PORT_PLUS_5

To avoid collusions with other backend worker jobs, leave the necessary gaps between ports. For instance, if your application uses three ports, specify the backend worker jobs 3 ports apart. For instance, cluster: 8000, 8003, 8006, 8009.

Cluster mode methodologies

There are two methodologies that can be used for the load-balancing activity:

1. http: This methodology has more customization options (for instance, microcaching, handling http headers, “sticky” sessions, etc) but only works with the http protocol. To enable, you must manually edit the “cluster.conf” file that is created when your service is first started.
2. stream (default): This methodology has less overhead than ‘http’, but also has fewer configuration options. However, it works with most protocols.

Cluster mode advanced configuration

More advanced configuration can be achieved in one of two ways:

Defining cluster_opts in the service configuration

This is NOT YET SUPPORTED

cluster.conf

When a service is first started in cluster mode, a cluster.conf file is created in the service’s working directory. Cluster mode is built on top of nginx, and this file is the nginx configuration file. Once cluster.conf is created, you can feel free to edit it in any way that is supported by nginx. For instance, this example:

• uses the http methodology for load balancing
• Enables 10-second request caching
• Enables a /tablesorter directory for serving static content

pid nginx.pid;
events {}
http {
  error_log logs/error.log warn;
  proxy_cache_path /tmp/cache keys_zone=cache:10m levels=1:2 inactive=600s max_size=100m;
  upstream sc_servers {
    server 127.0.0.1:3341;
    server 127.0.0.1:3342;
  }
  server {
    proxy_cache cache;
    proxy_cache_lock on;
    proxy_cache_valid 200 10s;
    proxy_cache_methods GET HEAD POST;
    proxy_cache_use_stale updating error timeout http_500 http_502 http_503 http_504;
    proxy_buffering on;
    listen 9333 backlog=8096;
    location / {
      proxy_pass http://sc_servers;
    }
    location /tablesorter {
      autoindex on;
      alias tablesorter/;
    }
  }
}

Automatically restarting a service if it fails

Currently, Service Commander does not have built-in monitoring and restart capabilities. This may be a future enhancement. In the meantime, one can use simple scripting to accomplish a similar task. For instance, to check every 40 seconds and ensure that the navigator service is running, you could submit a job like this (replace the sleep time, service name, and submitted job name to match your use case):

SBMJOB CMD(CALL PGM(QP2SHELL2) PARM('/QOpenSys/usr/bin/sh' '-c' 'while :; do sleep 40 && /QOpenSys/pkgs/bin/sc start navigator >/dev/null 2>&1 ; done')) JOB(NAVMON) JOBD(*USRPRF) JOBQ(QUSRNOMAX)

This will result in several jobs that continuously check on the service and attempt to start it if the service is dead. If you wish to stop this behavior, simply kill the jobs. In the above example, the job name is NAVMON, so the WRKACTJOB command to do this interactively looks like:

 WRKACTJOB JOB(NAVMON)

STRTCPSVR Integration

Service Commander now has integration with system STRTCPSVR and ENDTCPSVR commands.

To integrate with the STRTCPSVR and ENDTCPSVR commands, you can run the following command as an admin user:

/QOpenSys/pkgs/lib/sc/tcpsvr/install_sc_tcpsvr

This will create the SCOMMANDER library and compile/install the TCP program into that library. To use a different library, just set the SCTARGET variable. For instance:

SCTARGET=mylib /QOpenSys/pkgs/lib/sc/tcpsvr/install_sc_tcpsvr

If you need to compile to a previous release of IBM i, set the SCTGTRLS variable to the required value of CRTCMOD parameter TGTRLS. Example for IBM i 7.1:

SCTGTRLS=V7R1M0 /QOpenSys/pkgs/lib/sc/tcpsvr/install_sc_tcpsvr

After install, you can run the *SC TCP server commands, specifying the simple name of the sc-managed service as the instance name. For example:

STRTCPSVR SERVER(*SC) INSTANCE('kafka')

Important Note: As of Service Commander v1.2.x, the TCP server is set to AUTOSTART(*YES) by default. If this is not the desired behavior, change it with the CHGTCPSVR command. For instance:

CHGTCPSVR SVRSPCVAL(*SC) AUTOSTART(*NO)

Special groups used by STRTCPSVR/ENDTCPSVR

There are a couple special groups used by the TCP server support. You can define your services to be members of one or more of these groups:

• default, which is what’s started or ended if no instance is specified (i.e. STRTCPSVR SERVER(*SC))
• autostart, which is what’s started when invoked on the *AUTOSTART instance (i.e. STRTCPSVR SERVER(*SC) INSTANCE(*AUTOSTART))
• system, which contains the system services and is used when invoked on anything but the *ALL instance. This makes it possible to start or stop a system service using ServiceCommander. For instance, to end the NetServer service, run ENDTCPSVR SERVER(*SC) INSTANCE('system_netserver').

Running two or more STRTCPSVR commands simultaneously

Be aware that running two or more STRTCPSVR commands at the same time in different jobs can cause the command to fail with TCP1A11. This is because the system will only run one STRTCPSVR command at a time and uses an internal locking mechanism to control this. The wait time is 30 seconds, and if STRTCPSVR in job A is taking longer to start the service, the STRTCPSVR in job B and C etc. will time out when aquiring the lock.

If you need to run more than one STRTCPSVR *SC command at a time (e.g. after IPL where the system is busy and the service can take longer to start), you can reduce the lock time significantly by setting an environment variable before running the STRTCPSVR command:

ADDENVVAR ENVVAR(SC_TCPSVR_SUBMIT) VALUE('Y') LEVEL(*SYS) REPLACE(*YES)

When STRTCPSVR detects the environment variable having the value ‘Y’, it will submit a job to start the service instead of starting the service in the job running the STRTCPSVR command, thus shortening the lock time significantly and allow the same command in other jobs to run and not time out.

Using with ADDJOBSCDE

It may be desired to start, stop, or ensure the liveliness of services on a particular schedule. This is most easily accomplished once the STRTCPSVR integration is leveraged. This makes it easier to create job scheduler entries. For instance, to ensure that the myapp service is running, every day at 01:00:

ADDJOBSCDE JOB(SC) CMD(STRTCPSVR SERVER(*SC) INSTANCE('myapp')) FRQ(*WEEKLY) SCDDATE(*NONE) SCDDAY(*ALL) SCDTIME(010000)

Customize terminal Colors

ServiceCommander offers color support for the terminal output in different contexts, such as displaying the list of running and non-running services with sc check. Service Commander supports two configuration files where command line options can be configured:

• /QOpenSys/etc/sc/scrc (global)
• $HOME/.scrc (individual)

In order to configure terminal colors, add the following command with a comma separated list of CONTEXT:COLOR:

--color-scheme=[CONTEXT:COLOR], [CONTEXT:COLOR]

Example:

--color-scheme=NOT_RUNNING:BRIGHT_RED, INFO:YELLOW

Here is a list of the different contexts and default colors:

Terminal Color defaults and contexts used in sc:
      RUNNING: GREEN
      NOT_RUNNING: PURPLE
      INFO: CYAN
      WARNING: YELLOW
      ERROR: BRIGHT_RED
      PLAIN: WHITE
      STATUS: BLUE

Here is a list of the avalaible colors for customization:

- BLUE
- BRIGHT_RED
- CYAN
- GREEN
- PURPLE
- RED
- WHITE
- YELLOW

Demo (video)

Have feedback or want to contribute?

Feel free to open an issue with any questions, problems, or other comments. If you’d like to contribute to the project, see CONTRIBUTING.md for more information on how to get started.

In any event, we’re glad to have you aboard in any capacity, whether as a user, spectator, or contributor!

Thanks to everybody who has contributed so far!

Made with contrib.rocks.

Testimonials

“I use this a lot for my own personal use. Might be useless for the rest of the world. I don’t know, though.”

  –@ThePrez, creator of Service Commander

“Service Commander is a great tool that has helped us controlling the rising number of services, that we run on IBM i. Previously we had different commands for different services, but now we just define the services in Service Commander and let it control the (auto)start and stop of the services. Not at all useless!”

  –@chrjorgensen, IBM i System Administrator and contributor to Service Commander

“A fantastic tool to manage our many TCPSVR and Node.js instances. It’s got a great command line interface allowing us to run sc through our shell scripts. “

  –@KerimG, IBM i software developer and PASE for i enthusiast