I'm trying to write some tests for truffle, but I've realized that when running truffle test, before the test file is executed, truffle performs the compilation and migration of the contracts. For this reason, I need my oracle to be launched just after the migration because when launched it is waiting for events coming from a specific contract address.
Is there any way of launching the oracle programmatically and keeping it alive during the test? The command to launch it is simple, just something like node oracle.js --network=test
I guess my code is not needed for the question, but anyway, if you need to know any approach I'm following on the project feel free to ask about.
Thanks in advance.
You should be able to launch the oracle from any .js test file that requires the oracle to be running. You could likely accomplish this using a npm package such as forever.
Related
I have a server application using Node, and sometimes I need to run some script in it. Some examples of scenarios when this would be necessary:
During development, I need to create many entries in the database to simulate an use case.
In production, some bug happened and some information was not correctly stored in the DB, I may need to backfill it.
The way I know how do it in node is to deploy some instance of the server with an endpoint that contains the code to be run.
It is interesting to use the node server because it already has a lot of code that I can reused, for example DAO and safe create/delete funcitons.
Django has a interactive Python interpreter that does this job, but I do not know any similar way to it in Node.
Other strategies of doing this use cases are very welcome.
During development, you can just go with debugging, although that requires triggering a breakpoint. Alternatively, if it's just about your database, there are better external programs to interact with your database.
To actually answer your question: Node does have a VM module to run code and even a REPL module to help writing custom REPLs. This does require some work to link up your APIs though, but doable.
As for how you actually interact with that REPL, there are several options. Using a raw socket (and Telnet), a terminal on your site communicating over a WebSocket, a simple HTTP endpoint, ...
You can add scripts in your package.json to handle this with a path to the script. For example "seed:db": "node ./src/seeder.js -i", "drop:db": "node ./src/seeder.js -d" where the i an d flags will be used to determine if i am inserting or deleting, and can be gotten with process.argv[2]
According to Uber it's possible to deploy code to node without restart. Where can I read more about this? I expecting it's not forever or pm2.
That’s where the second strength Uber found in Node.js (quick iteration) comes into play:
through an interactive testing environment called REPL - Read Eval Print Loop - JavaScript allows
developers to deploy new code - and fix the errors that new code may create - without having to
stop any processes.
“One of the things that makes Node.js uniquely suited to running in production is that you can
inspect and change a program without restarting it,” said Ranney. “So very few other languages
offer that capability. Not a lot of people seem to know that ability exists, but indeed you can
inspect and even change your program while it’s running without restarting it.”
Source: https://nodejs.org/static/documents/casestudies/Nodejs-at-Uber.pdf
I'm receiving SIGSEGV quite randomly when running an express app with PM2. The strange thing is the server runs quite well for the past few weeks. It does not print any error message except:
App [XXX] with id [7] and pid [27757], exited with code [255] via signal [SIGSEGV]
After implementing the "segfault-handler" module, I started to receive some stack traces. It seems the app encounters a few different segmentation fault:
/lib/x86_64-linux-gnu/libpthread.so.0(+0x10330)[0x7fd211f87330]
node(_ZN2v88internal9HashTableINS0_15ObjectHashTableENS0_20ObjectHashTableShapeENS0_6HandleINS0_6ObjectEEEE18FindInsertionEntryEj+0x40)[0xc0b680]
node(_ZN2v88internal15ObjectHashTable3PutENS0_6HandleIS1_EENS2_INS0_6ObjectEEES5_i+0x124)[0xc0c0a4]
node(_ZN2v88internal7Runtime17WeakCollectionSetENS0_6HandleINS0_16JSWeakCollectionEEENS2_INS0_6ObjectEEES6_i+0x59)[0xc7d639]
node(_ZN2v88internal25Runtime_WeakCollectionSetEiPPNS0_6ObjectEPNS0_7IsolateE+0x11d)[0xc7d89d]
[0x2acdd80963b]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x10330)[0x7f0fc311c330]
node(_ZN2v88internal32IncrementalMarkingMarkingVisitor26VisitFixedArrayIncrementalEPNS0_3MapEPNS0_10HeapObjectE+0x376)[0xad8a16]
node(_ZN2v88internal18IncrementalMarking4StepElNS1_16CompletionActionENS1_18ForceMarkingActionENS1_21ForceCompletionActionE+0x2c1)[0xad6181]
node(_ZN2v88internal8NewSpace15SlowAllocateRawEiNS0_19AllocationAlignmentE+0x74)[0xb05244]
node(_ZN2v88internal4Heap11AllocateRawEiNS0_15AllocationSpaceES2_NS0_19AllocationAlignmentE+0x1b9)[0xa678c9]
node(_ZN2v88internal4Heap20AllocateFillerObjectEibNS0_15AllocationSpaceE+0x19)[0xab00b9]
node(_ZN2v88internal7Factory15NewFillerObjectEibNS0_15AllocationSpaceE+0x2d)[0xa67d1d]
node(_ZN2v88internal29Runtime_AllocateInTargetSpaceEiPPNS0_6ObjectEPNS0_7IsolateE+0x5e)[0xc99e8e]
[0x249862c06355]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x10330)[0x7fbebabd2330]
node(_ZN2v88internal9HashTableINS0_15ObjectHashTableENS0_20ObjectHashTableShapeENS0_6HandleINS0_6ObjectEEEE18FindInsertionEntryEj+0x40)[0xc0b680]
node(_ZN2v88internal15ObjectHashTable3PutENS0_6HandleIS1_EENS2_INS0_6ObjectEEES5_i+0x124)[0xc0c0a4]
node(_ZN2v88internal7Runtime17WeakCollectionSetENS0_6HandleINS0_16JSWeakCollectionEEENS2_INS0_6ObjectEEES6_i+0x59)[0xc7d639]
node(_ZN2v88internal25Runtime_WeakCollectionSetEiPPNS0_6ObjectEPNS0_7IsolateE+0x11d)[0xc7d89d]
[0x125b9620963b]
I know there is little information here. Can anyone please tell me a good way to start diagnosing? I've checked the PM2 log, mongoDB log but no luck.
Thanks!
Mars
Since the stack trace is different every time and not very illuminating, all you can do is try things. The first main suspects will be things that use native code because it's not that likely that plain Javascript is causing a segFault. It is probably native code that is somehow corrupting memory or not properly interacting with the garbage collector in node.js.
So, the things to look for are the interaction between your current version of node.js and the things you have that use native code (such as mongoDB). Here are things to try:
Identify all modules that use native code and temporarily remove any that you can live without.
Upgrade both node.js and mongoDB to recent versions in case you have some interaction between their specific versions that is causing the problem. If you can't upgrade node.js to a recent stable version, then make absolutely sure that all the modules you are running are certified to be stable with the version of node.js that you do have.
Restart your server just in case there's anything goofed up in the OS that is contributing to the problem.
Start with a clean database or run some sort of database check on your database in order to verify that there is no corruption there.
Whenever you update your DB scheme, make sure you have a strategy for moving the prior database forward (it looks like in MongoDB you can just make sure you assign a default value to new scheme elements).
Gather new info after making changes and repeat the process, trying to only change one thing at a time so that if it fixes the issue you will know exactly which item it was that fixed it.
Something like that can happen when you copy the code with node_modules that included binary modules compiled for a different architecture than the one you're trying to run it on.
Try either removing node_modules and running npm install from scratch, or you can try running npm rebuild without removing node_modules.
I need to create a nodejs "server" which wont actually serve any assets or content, but will just run some scheduled job to fetch contents from one database and update another database. The schedule of the job should be configurable and should be able to cancel the job at any time. Basically what I need is to run a node script periodically. In past, I have created node/express projects, but I am having a hard time understanding how to implement such a node instance which will run on a remote machine and how to start or terminate it. I found a npm package called "node-schedule" which runs the job periodically, but how to put this package on a remote machine instance and run it?
One possibility that was considered was to schedule a cron job on remote machine which will execute "node updateDB.js" on set schedule, but it is a requirement to keep everything in node package and not depend on cron.
Sounds like a job for ssh.
Personally I wouldn't use NodeJS for this, this should be pretty trivial to do, with Node or otherwise, not sure why you are stuck, honestly. I have nothing against Node, but I don't see why it would be necessary for this task, but certainly you could use it for such a thing.
EDIT: After reading your comment I'm convinced someone thinks Node is a good tool for this task. I guess I don't understand where you are stuck. What part are you stuck on?
I think you should be able to puzzle this out pretty fast. The link below should be enough to put this together. http://book.mixu.net/node/ch9.html
If you need to execute ad hoc commands on a remote server you could use Node to call an Ansible playbook, in that case you'll need to share the public ssh key on the target instance(s) with the instance issuing the commands. There are other ways to skin this cat, but based on the information given, that's how I'd do it. I'd use Node and Ansible (requires python) + SSH.
Oh neato, maybe if I were forced to use NodeJS I'd use this package. https://www.npmjs.com/package/ssh2-exec
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I'm a newbie JavaScript programmer who wants to experiment with server side JavaScript using Node.Js on my Mac
I downloaded NodeJs and the wizard installed it, but now I can't see it in my applications?
1) How do I open it and start using it? Do I do it from the command line? if so, how do I start?
2) Can I connect it to a MySQL database I have installed with MAMP?
Thanks if you can help
To start node, you open a terminal and type:
/path/to/node scriptname.js
Depending on how you installed node, the actual location of node may vary. You should figure that out. You should probably add that path to your PATH environment variable. If you do this then you can simply type
node scriptname.js
There are plenty of samples around the net. As for mysql connectivity, check this out.
I am in pretty much in the same boat as you are, and I highly recommend you to watch the meetup talk by Ryan Dahl on http://nodejs.org/
It is only about an hour long, but it pretty shows you how you can use it for your own non-blocking applications.
In terms of driver for accessing SQL, you will need to install NPM http://npmjs.org/
You can do a quick search http://search.npmjs.org/, on the support for MySQL. Because node.js is still relatively new to the scene, you will see quite a bit of choices competing to meet your goal