Re: Defining environment variables for a webapp ?
Nirjan, On 4/26/21 14:19, Niranjan Rao wrote: On 4/14/21 5:29 AM, Rony G. Flatscher (Apache) wrote: A JVM AFAIK would not honor changes to the environment after it got started A serious question. Apologies for selective selection from the response. Are there any operating systems where change in environment is automatically reflected in child process? That would be a fairly chaotic system. I don't know of any that do this kind of thing. My understanding was, processes always inherit parent environment and have no way of knowing what changed. A copy of the parent environment is made into the child process, which diverges from that point forward. The reason JVMs "would not honor changes to the environment after it got started" is because most components that configure based upon envirnment variables (or system properties for that matter) only check them when first initialized. If you change an environment variable in a process (whether from the inside or the outside), it only changes behavior of the variable's value is directly-checked periodically instead of "just once at startup." If you managed to spawn a process with different parent based on your operating system, then you might see new values, but most of the spawn/exec calls (regardless of language of implmentation) inherit the exact same environment variables. Some calls do allow you to setup the environment variables for child process but struggling to figure out where grandparent process informed parent about environment change which can be sent to grandchild. I don't believe any of that can happen, at least not in theway you describe. Of course, IPC does exist and you *can* send data between processes, so a grantparent process could theoretically tell the grandchild process "hey you should set FOO=bar" but the grandchild process would have to support that kind of IPC and agree to make the change. The gp process can't just reach-in and change the environment. -chris - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Defining environment variables for a webapp ?
Niranjan:
one correction:
On 27.04.2021 15:05, Rony G. Flatscher (Apache) wrote:
> ("heyhey.bat" is executed in a subprocess with a new environment such that
> its PATH value is
> unchanged!).
the above statement is wrong, the current environment is inherited with ooRexx'
ADDRESS instruction
to run commands, sorry, should have double-checked before posting! :(
---rony
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Re: Defining environment variables for a webapp ?
On 26.04.2021 20:19, Niranjan Rao wrote:
> On 4/14/21 5:29 AM, Rony G. Flatscher (Apache) wrote:
>> A JVM
>> AFAIK would not honor changes to the environment after it got started
>
> A serious question. Apologies for selective selection from the response.
>
> Are there any operating systems where change in environment is automatically
> reflected in child
> process? My understanding was, processes always inherit parent environment
> and have no way of
> knowing what changed.
>
> If you managed to spawn a process with different parent based on your
> operating system, then you
> might see new values, but most of the spawn/exec calls (regardless of
> language of implmentation)
> inherit the exact same environment variables. Some calls do allow you to
> setup the environment
> variables for child process but struggling to figure out where grandparent
> process informed parent
> about environment change which can be sent to grandchild.
Well, it depends what one does, e.g. spawning a new process is different than
e.g. changing PATH in
the same process and then relying on the new value for PATH to take effect when
looking for programs
to run/execute.
An example (Windows, ooRexx):
test.rex ... an ooRexx script that uses Rexx to find "subdir\hey.rex" and
uses Windows to find
"subdir\heyhey.bat", both depend on PATH (which gets changed in the running
program and takes
effect as can be seen by the output below); failure is shown with frownies,
success with smileys :)
subdir\hey.rex ... an ooRexx script displaying the invocation information
(operating system, how
invoked, fully qualified path to this program) and the current dir
subdir\heyhey.bat ... a batch file displaying some environment variable
('windir')
Here the output of running "test.rex":
G:\test\orx\env>test.rex
1a) testcall():
:-( | not found!
1b) testcallbat():
'heyhey.bat' is not recognized as an internal or external command,
operable program or batch file.
:-( | not found! | RC=1
... about to add 'G:\test\orx\env\subdir' to PATH ...
2a) testcall():
--> hey.rex: parse source s: [WindowsNT SUBROUTINE
G:\test\orx\env\subdir\hey.rex]
--> hey.rex: directory() : [G:\test\orx\env]
:-) | ok!
2b) testcallbat():
*** heyhey.bat: just arrived ***
*** heyhey.bat: windir=C:\WINDOWS ***
*** heyhey.bat: about to return ***
:-) | RC=0
As long as PATH does not contain the "subdir" directory neither "hey.rex" nor
"heyhey.bat" (this
even causes an error message) are found by Rexx or Windows, cf. 1a) and 1b
(displays the return code
next to the frownie) above. Once the "subdir" directory gets added in the
running program (in the
same process) and both programs are found by Rexx and Windows as can be seen by
the output 2a) and
2b) ("heyhey.bat" is executed in a subprocess with a new environment such that
its PATH value is
unchanged!).
HTH,
---rony
P.S.: For the record the three files:
subdir\hey.rex:
#!/usr/bin/env rexx
parse source s -- get invocation information
say "--> hey.rex:" "parse source s: ["s"]" -- show invocation
information
say "--> hey.rex:" "directory() : ["directory()"]" -- show current
directory
subdir\heyhey.bat:
@echo off
echo *** heyhey.bat: just arrived ***
echo *** heyhey.bat: windir=%windir% ***
echo *** heyhey.bat: about to return ***
test.rex:
#!/usr/bin/env rexx
say "1a) testcall():" -- call a Rexx program
say testCall()
say "1b) testcallbat():"
res=testcallbat() -- invoke a command
say res
say
newDir=directory()"\subdir"
say "... about to add '"newDir"' to PATH ..."
-- define new value for PATH
newValue=value('PATH', ,"environment")";"newDir
oldValue=value('PATH', newValue, "environment") -- change PATH value
say
say "2a) testcall():" -- call a Rexx program
say testCall()
say "2b) testcallbat():" -- invoke a command
res=testcallbat() -- invoke a command
say res
::routine testcall -- call another Rexx program
signal on syntax -- if syntax exception then jump to label "syntax:"
call hey.rex -- call the Rexx program, PATH gets searched
return ":-) | ok!"-- everything went fine, return a smiley
syntax: -- label
return ":-( | not found!" -- return frownie
::routine testcallbat -- call a Windows batch file
address system "heyhey.bat" -- let Window search and execute the command
if rc=0 then return ":-) | RC="rc -- if return code is 0 return smiley
return ":-( | not found! | RC="rc -- return code indicates
problem, return frownie
Re: Defining environment variables for a webapp ?
On 4/14/21 5:29 AM, Rony G. Flatscher (Apache) wrote: A JVM AFAIK would not honor changes to the environment after it got started A serious question. Apologies for selective selection from the response. Are there any operating systems where change in environment is automatically reflected in child process? My understanding was, processes always inherit parent environment and have no way of knowing what changed. If you managed to spawn a process with different parent based on your operating system, then you might see new values, but most of the spawn/exec calls (regardless of language of implmentation) inherit the exact same environment variables. Some calls do allow you to setup the environment variables for child process but struggling to figure out where grandparent process informed parent about environment change which can be sent to grandchild. Regards, Niranjan - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Defining environment variables for a webapp ?
Martynas, On 14.04.2021 14:20, Martynas Jusevičius wrote: > you might want to look into containerizing your webapps. We use an > XSLT stylesheet (invoked by the entrypoint script) that transforms env > params into context.xml params: > https://github.com/AtomGraph/LinkedDataHub/blob/master/platform/context.xsl Thank you very much! If I understood Mark correctly, the environment variable values need to be set in the Tomcat process before Tomcat starts. The aim would be to change the environment for the webapps, i.e. in a running Tomcat instance. A JVM AFAIK would not honor changes to the environment after it got started, but thought it possible that through some magic :) by the Tomcat developers this could be achieved for webapps. The CGI solution works with a new environment as a new (relative expensive) process gets created through Java for which all these aspects could be set. ---rony > On Wed, Apr 14, 2021 at 2:16 PM Rony G. Flatscher (Apache) > wrote: >> On 14.04.2021 13:25, Mark Thomas wrote: >>> On 14/04/2021 12:22, Rony G. Flatscher (Apache) wrote: Not finding any pointers, asking here: is it possible to define environment variables for a webapp? If so, how? >>> You can only set them globally, for the Java process - not per web >>> application. >>> >>> CGI creates a new process so can have a completely different set of >>> environment variables. >>> >>> How about using the per web application JNDI context? >> Well the idea was to adjust PATH to have it point to a webapp based >> directory containing the >> binaries. :) >> >> ---rony >> >> P.S.: The aim would be to make it simple and easy for deploying webapps that >> also need to have >> access to non-Java binaries (executables and/or shared libraries). >> >> >> - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Defining environment variables for a webapp ?
Rony, you might want to look into containerizing your webapps. We use an XSLT stylesheet (invoked by the entrypoint script) that transforms env params into context.xml params: https://github.com/AtomGraph/LinkedDataHub/blob/master/platform/context.xsl Martynas On Wed, Apr 14, 2021 at 2:16 PM Rony G. Flatscher (Apache) wrote: > > On 14.04.2021 13:25, Mark Thomas wrote: > > On 14/04/2021 12:22, Rony G. Flatscher (Apache) wrote: > >> Not finding any pointers, asking here: is it possible to define > >> environment variables for a webapp? > >> If so, how? > > > > You can only set them globally, for the Java process - not per web > > application. > > > > CGI creates a new process so can have a completely different set of > > environment variables. > > > > How about using the per web application JNDI context? > > Well the idea was to adjust PATH to have it point to a webapp based directory > containing the > binaries. :) > > ---rony > > P.S.: The aim would be to make it simple and easy for deploying webapps that > also need to have > access to non-Java binaries (executables and/or shared libraries). > > > > - > To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org > For additional commands, e-mail: users-h...@tomcat.apache.org > - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Defining environment variables for a webapp ?
On 14.04.2021 13:25, Mark Thomas wrote: > On 14/04/2021 12:22, Rony G. Flatscher (Apache) wrote: >> Not finding any pointers, asking here: is it possible to define environment >> variables for a webapp? >> If so, how? > > You can only set them globally, for the Java process - not per web > application. > > CGI creates a new process so can have a completely different set of > environment variables. > > How about using the per web application JNDI context? Well the idea was to adjust PATH to have it point to a webapp based directory containing the binaries. :) ---rony P.S.: The aim would be to make it simple and easy for deploying webapps that also need to have access to non-Java binaries (executables and/or shared libraries). - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Re: Defining environment variables for a webapp ?
On 14/04/2021 12:22, Rony G. Flatscher (Apache) wrote: Not finding any pointers, asking here: is it possible to define environment variables for a webapp? If so, how? You can only set them globally, for the Java process - not per web application. CGI creates a new process so can have a completely different set of environment variables. How about using the per web application JNDI context? Mark ---rony P.S.: Tomcat can manipulate the process' environment, e.g. in the case of CGI execution. Here a sample of the process' environment from some CGI-invocation on a Windows machine: (debug) current cgi process environment:|| 1. |AUTH_TYPE= 2. COMSPEC=C:\WINDOWS\SysWOW64\CMD.EXE 3. CONTENT_LENGTH=7 4. CONTENT_TYPE=application/x-www-form-urlencoded 5. GATEWAY_INTERFACE=CGI/1.1 6. HTTP_ACCEPT=text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 7. HTTP_ACCEPT_ENCODING=gzip, deflate 8. HTTP_ACCEPT_LANGUAGE=en-US,en;q=0.5 9. HTTP_COOKIE=JSESSIONID=2137ECEC8CC5EE35AEFA475E5C5D8250 10. HTTP_HOST=localhost:8080 11. HTTP_REFERER=http://localhost:8080/demoSTL-Core-SQL_ooRexx/JSTL_CGI_05-GroupWorkDivider.jsp 12. HTTP_USER_AGENT=Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:87.0) Gecko/20100101 Firefox/87.0 13. PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.JS;.WS;.MSC 14. PATH_INFO= 15. PROMPT=$P$G 16. QUERY_STRING=name=Andreas+Burgstaller&name=Max+Mustermann&name=Nadine+Berger&name=Klaus+Karter&name=Simon+Hauser&name=Michael+Nimmervoll 17. REMOTE_ADDR=127.0.0.1 18. REMOTE_HOST=127.0.0.1 19. REMOTE_IDENT= 20. REMOTE_USER= 21. REQUEST_METHOD=POST 22. REQUEST_URI=/demoSTL-Core-SQL_ooRexx/cgi-bin/groupStudents.rexx 23. RXQUEUESESSION=3B1C 24. SCRIPT_FILENAME=D:\Apache Software Foundation\Tomcat 9.0\webapps\demoSTL-Core-SQL_ooRexx\WEB-INF\cgi\groupStudents.rexx 25. SCRIPT_NAME=/demoSTL-Core-SQL_ooRexx/cgi-bin/groupStudents.rexx 26. SERVER_NAME=localhost 27. SERVER_PORT=8080 28. SERVER_PROTOCOL=HTTP/1.1 29. SERVER_SOFTWARE=TOMCAT 30. SystemRoot=C:\WINDOWS 31. X_TOMCAT_SCRIPT_PATH=D:\Apache Software Foundation\Tomcat 9.0\webapps\demoSTL-Core-SQL_ooRexx\WEB-INF\cgi\groupStudents.rexx | - To unsubscribe, e-mail: users-unsubscr...@tomcat.apache.org For additional commands, e-mail: users-h...@tomcat.apache.org
Defining environment variables for a webapp ?
Not finding any pointers, asking here: is it possible to define environment variables for a webapp? If so, how? ---rony P.S.: Tomcat can manipulate the process' environment, e.g. in the case of CGI execution. Here a sample of the process' environment from some CGI-invocation on a Windows machine: (debug) current cgi process environment:|| 1. |AUTH_TYPE= 2. COMSPEC=C:\WINDOWS\SysWOW64\CMD.EXE 3. CONTENT_LENGTH=7 4. CONTENT_TYPE=application/x-www-form-urlencoded 5. GATEWAY_INTERFACE=CGI/1.1 6. HTTP_ACCEPT=text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8 7. HTTP_ACCEPT_ENCODING=gzip, deflate 8. HTTP_ACCEPT_LANGUAGE=en-US,en;q=0.5 9. HTTP_COOKIE=JSESSIONID=2137ECEC8CC5EE35AEFA475E5C5D8250 10. HTTP_HOST=localhost:8080 11. HTTP_REFERER=http://localhost:8080/demoSTL-Core-SQL_ooRexx/JSTL_CGI_05-GroupWorkDivider.jsp 12. HTTP_USER_AGENT=Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:87.0) Gecko/20100101 Firefox/87.0 13. PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.JS;.WS;.MSC 14. PATH_INFO= 15. PROMPT=$P$G 16. QUERY_STRING=name=Andreas+Burgstaller&name=Max+Mustermann&name=Nadine+Berger&name=Klaus+Karter&name=Simon+Hauser&name=Michael+Nimmervoll 17. REMOTE_ADDR=127.0.0.1 18. REMOTE_HOST=127.0.0.1 19. REMOTE_IDENT= 20. REMOTE_USER= 21. REQUEST_METHOD=POST 22. REQUEST_URI=/demoSTL-Core-SQL_ooRexx/cgi-bin/groupStudents.rexx 23. RXQUEUESESSION=3B1C 24. SCRIPT_FILENAME=D:\Apache Software Foundation\Tomcat 9.0\webapps\demoSTL-Core-SQL_ooRexx\WEB-INF\cgi\groupStudents.rexx 25. SCRIPT_NAME=/demoSTL-Core-SQL_ooRexx/cgi-bin/groupStudents.rexx 26. SERVER_NAME=localhost 27. SERVER_PORT=8080 28. SERVER_PROTOCOL=HTTP/1.1 29. SERVER_SOFTWARE=TOMCAT 30. SystemRoot=C:\WINDOWS 31. X_TOMCAT_SCRIPT_PATH=D:\Apache Software Foundation\Tomcat 9.0\webapps\demoSTL-Core-SQL_ooRexx\WEB-INF\cgi\groupStudents.rexx |
